Loading ...
Sorry, an error occurred while loading the content.

Hard time with horizon

Expand Messages
  • Fabio Bustamante
    I am trying to stitch a pano but I m having the hardest time ever. Could someone help me figure this out? The pano was made at sea, 5 km from the coast, over
    Message 1 of 30 , Oct 28, 2008
    • 0 Attachment
      I am trying to stitch a pano but I'm having the hardest time ever. Could
      someone help me figure this out?

      The pano was made at sea, 5 km from the coast, over shallow reefs. The
      reefs were all covered with water but shallow enough to set the tripod
      firmly. Since there's water all around my only reference is the horizon,
      which is pretty featureless, by the way. I took 4 horizontal shots with
      my 5D and a Nikon 10.5.

      Well, this should have been *the* piece of cake. "Just align each shot's
      horizon and you're done", I though. Since I used an Agnos head with 4
      quite reliable horizontal stops, I was willing to use arbitrary yaw
      values and optmize only pitch and roll in order to make the horizon a
      perfect line. I also have all parameters I would need from other panos,
      like fov, a, b, c, hor shift, vert. shift, etc.

      Problem is I just can't make it happen. Tried several approaches... one,
      two or three pairs of horizontal points per shot... "straight line"
      points just gave me weird results... going nuts here. Sometimes the
      optmizer gives me a roller coaster horizon despite the several control
      points for horizontal lines.

      Any hint will be appreciated!
    • Sacha Griffin
      You probably have a vertical point set somewhere instead of a horizontal point. Sacha Griffin Southern Digital Solutions LLC http://www.southern-digital.com
      Message 2 of 30 , Oct 28, 2008
      • 0 Attachment
        You probably have a vertical point set somewhere instead of a horizontal
        point.





        Sacha Griffin

        Southern Digital Solutions LLC

        http://www.southern-digital.com

        http://www.seeit360.net

        404-551-4275







        From: PanoToolsNG@yahoogroups.com [mailto:PanoToolsNG@yahoogroups.com] On
        Behalf Of Fabio Bustamante
        Sent: Tuesday, October 28, 2008 11:00 AM
        To: PanoToolsNG@yahoogroups.com
        Subject: [PanoToolsNG] Hard time with horizon



        I am trying to stitch a pano but I'm having the hardest time ever. Could
        someone help me figure this out?

        The pano was made at sea, 5 km from the coast, over shallow reefs. The
        reefs were all covered with water but shallow enough to set the tripod
        firmly. Since there's water all around my only reference is the horizon,
        which is pretty featureless, by the way. I took 4 horizontal shots with
        my 5D and a Nikon 10.5.

        Well, this should have been *the* piece of cake. "Just align each shot's
        horizon and you're done", I though. Since I used an Agnos head with 4
        quite reliable horizontal stops, I was willing to use arbitrary yaw
        values and optmize only pitch and roll in order to make the horizon a
        perfect line. I also have all parameters I would need from other panos,
        like fov, a, b, c, hor shift, vert. shift, etc.

        Problem is I just can't make it happen. Tried several approaches... one,
        two or three pairs of horizontal points per shot... "straight line"
        points just gave me weird results... going nuts here. Sometimes the
        optmizer gives me a roller coaster horizon despite the several control
        points for horizontal lines.

        Any hint will be appreciated!





        [Non-text portions of this message have been removed]
      • Fabio Bustamante
        Not the case, Sacha... I checked for it.
        Message 3 of 30 , Oct 28, 2008
        • 0 Attachment
          Not the case, Sacha... I checked for it.

          Sacha Griffin wrote:
          > You probably have a vertical point set somewhere instead of a horizontal
          > point.
        • Sacha Griffin
          Then you ll have to upload your whole project. There are too many variables. Try switching to panotools optimizer. Sometimes that helps in narrowing down the
          Message 4 of 30 , Oct 28, 2008
          • 0 Attachment
            Then you'll have to upload your whole project. There are too many variables.

            Try switching to panotools optimizer. Sometimes that helps in narrowing down
            the problem.



            Sacha Griffin

            Southern Digital Solutions LLC

            http://www.southern-digital.com

            http://www.seeit360.net

            404-551-4275









            From: PanoToolsNG@yahoogroups.com [mailto:PanoToolsNG@yahoogroups.com] On
            Behalf Of Fabio Bustamante
            Sent: Tuesday, October 28, 2008 11:05 AM
            To: PanoToolsNG@yahoogroups.com
            Subject: Re: [PanoToolsNG] Hard time with horizon



            Not the case, Sacha... I checked for it.

            Sacha Griffin wrote:
            > You probably have a vertical point set somewhere instead of a horizontal
            > point.

            .


            <http://geo.yahoo.com/serv?s=97359714/grpId=18227848/grpspId=1705006496/msgI
            d=24083/stime=1225206307/nc1=4763761/nc2=4025291/nc3=5349274>




            [Non-text portions of this message have been removed]
          • Thomas Krueger
            Try with an old and successfull PTGUI project file as a template where used the same gear. ... Greetings, Thomas - http://www.thomaskrueger.eu
            Message 5 of 30 , Oct 28, 2008
            • 0 Attachment
              Try with an old and successfull PTGUI project file as a template where used
              the same gear.

              -----
              Greetings, Thomas - http://www.thomaskrueger.eu thomaskrueger.eu
              --
              View this message in context: http://www.nabble.com/Hard-time-with-horizon-tp20208861p20209030.html
              Sent from the PanoToolsNG mailing list archive at Nabble.com.
            • crane@ukonline.co.uk
              ... sometimes I use the panorama editor to try to straighten things like that. probably it wants to be lower in the frame. regards mick ... This mail sent
              Message 6 of 30 , Oct 28, 2008
              • 0 Attachment
                Quoting Fabio Bustamante <contato@...>:

                > Not the case, Sacha... I checked for it.

                sometimes I use the panorama editor to try to straighten things like that.
                probably it wants to be lower in the frame.

                regards

                mick



                > Sacha Griffin wrote:
                > > You probably have a vertical point set somewhere instead of a horizontal
                > > point.
                >
                > ------------------------------------
                >
                > --
                >
                >
                >
                >




                ----------------------------------------------
                This mail sent through http://www.ukonline.net
              • Dominique Salino
                Hello, For this situation I met I found the solution : equirectangural panorama from altostorm (an add on for photoshop).. Dominique Salino New Caledonia, The
                Message 7 of 30 , Oct 28, 2008
                • 0 Attachment
                  Hello,

                  For this situation I met I found the solution : equirectangural panorama
                  from altostorm (an add on for photoshop)..

                  Dominique Salino

                  New Caledonia,
                  The closest Island to paradise

                  2008/10/29 Fabio Bustamante <contato@...>

                  > I am trying to stitch a pano but I'm having the hardest time ever. Could
                  >
                  > someone help me figure this out?
                  >
                  > The pano was made at sea, 5 km from the coast, over shallow reefs. The
                  > reefs were all covered with water but shallow enough to set the tripod
                  > firmly. Since there's water all around my only reference is the horizon,
                  > which is pretty featureless, by the way. I took 4 horizontal shots with
                  > my 5D and a Nikon 10.5.
                  >
                  > Well, this should have been *the* piece of cake. "Just align each shot's
                  > horizon and you're done", I though. Since I used an Agnos head with 4
                  > quite reliable horizontal stops, I was willing to use arbitrary yaw
                  > values and optmize only pitch and roll in order to make the horizon a
                  > perfect line. I also have all parameters I would need from other panos,
                  > like fov, a, b, c, hor shift, vert. shift, etc.
                  >
                  > Problem is I just can't make it happen. Tried several approaches... one,
                  > two or three pairs of horizontal points per shot... "straight line"
                  > points just gave me weird results... going nuts here. Sometimes the
                  > optmizer gives me a roller coaster horizon despite the several control
                  > points for horizontal lines.
                  >
                  > Any hint will be appreciated!
                  >
                  >


                  [Non-text portions of this message have been removed]
                • John Houghton
                  ... One solution would be to create an artificial horizon in an additional image in equirectangular format. The horizon would run straight across the centre
                  Message 8 of 30 , Oct 28, 2008
                  • 0 Attachment
                    --- In PanoToolsNG@yahoogroups.com, Fabio Bustamante <contato@...>
                    wrote:
                    >
                    > Tried several approaches... one,
                    > two or three pairs of horizontal points per shot... "straight line"
                    > points just gave me weird results... going nuts here. Sometimes the
                    > optmizer gives me a roller coaster horizon despite the several
                    > control points for horizontal lines.
                    >
                    > Any hint will be appreciated!

                    One solution would be to create an artificial horizon in an additional
                    image in equirectangular format. The horizon would run straight across
                    the centre of the image. Use individual lens parameters for this image
                    (hfov=360). All you do then is assign a couple of t3 points between
                    each image and the artificial horizon, like hanging them on a washing
                    line. The yaw values are known and can be assigned manually. Just
                    optimize p & r on the four images and they should line up perfectly,
                    assuming your lens parameters are good. (Must use the Pano Tools
                    optimizer for this, of course). Exclude the artificial horizon image
                    via the Include Images list when you generate the output.

                    John
                  • Sacha Griffin
                    Honestly, in a situation where there is an actual Gravitational Field of water in all shots, and you can not level your 360. You ve made a bonehead mistake
                    Message 9 of 30 , Oct 28, 2008
                    • 0 Attachment
                      Honestly, in a situation where there is an actual Gravitational Field of
                      water in all shots, and you can not level your 360.

                      You've made a bonehead mistake somewhere.

                      It's just finding it, and we've all been there.





                      Sacha Griffin

                      Southern Digital Solutions LLC

                      http://www.southern-digital.com

                      http://www.seeit360.net

                      404-551-4275







                      From: PanoToolsNG@yahoogroups.com [mailto:PanoToolsNG@yahoogroups.com] On
                      Behalf Of John Houghton
                      Sent: Tuesday, October 28, 2008 7:02 PM
                      To: PanoToolsNG@yahoogroups.com
                      Subject: [PanoToolsNG] Re: Hard time with horizon



                      --- In PanoToolsNG@yahoogroups.com <mailto:PanoToolsNG%40yahoogroups.com> ,
                      Fabio Bustamante <contato@...>
                      wrote:
                      >
                      > Tried several approaches... one,
                      > two or three pairs of horizontal points per shot... "straight line"
                      > points just gave me weird results... going nuts here. Sometimes the
                      > optmizer gives me a roller coaster horizon despite the several
                      > control points for horizontal lines.
                      >
                      > Any hint will be appreciated!

                      One solution would be to create an artificial horizon in an additional
                      image in equirectangular format. The horizon would run straight across
                      the centre of the image. Use individual lens parameters for this image
                      (hfov=360). All you do then is assign a couple of t3 points between
                      each image and the artificial horizon, like hanging them on a washing
                      line. The yaw values are known and can be assigned manually. Just
                      optimize p & r on the four images and they should line up perfectly,
                      assuming your lens parameters are good. (Must use the Pano Tools
                      optimizer for this, of course). Exclude the artificial horizon image
                      via the Include Images list when you generate the output.

                      John





                      [Non-text portions of this message have been removed]
                    • Luca N Vascon
                      Fabio, post it and I ll fix it and than tell you. I d use a template made with the same setup... ... -- IUAV università degli studi, Venezia Dr. Luca Vascon
                      Message 10 of 30 , Oct 28, 2008
                      • 0 Attachment
                        Fabio, post it and I'll fix it and than tell you.
                        I'd use a template made with the same setup...


                        Fabio Bustamante ha scritto:
                        >
                        > Not the case, Sacha... I checked for it.
                        >
                        > Sacha Griffin wrote:
                        > > You probably have a vertical point set somewhere instead of a horizontal
                        > > point.
                        >
                        >

                        --
                        IUAV università degli studi, Venezia

                        Dr. Luca Vascon
                        tel . (+39) 041.2571262, e-mail vascon@...

                        laboratorio multimedia Facoltà di Design e Arti, DADI
                        Magazzino 7 ex Ligabue, Dorsoduro 1827 30123 Venezia
                      • Fabio Bustamante
                        This is a great idea, John! Although I must confess I never clearly understood the function of the t3 lines... I ll check it out.
                        Message 11 of 30 , Oct 28, 2008
                        • 0 Attachment
                          This is a great idea, John!

                          Although I must confess I never clearly understood the function of the
                          t3 lines... I'll check it out.

                          John Houghton wrote:
                          > --- In PanoToolsNG@yahoogroups.com, Fabio Bustamante <contato@...>
                          > wrote:
                          >
                          >> Tried several approaches... one,
                          >> two or three pairs of horizontal points per shot... "straight line"
                          >> points just gave me weird results... going nuts here. Sometimes the
                          >> optmizer gives me a roller coaster horizon despite the several
                          >> control points for horizontal lines.
                          >>
                          >> Any hint will be appreciated!
                          >>
                          >
                          > One solution would be to create an artificial horizon in an additional
                          > image in equirectangular format. The horizon would run straight across
                          > the centre of the image. Use individual lens parameters for this image
                          > (hfov=360). All you do then is assign a couple of t3 points between
                          > each image and the artificial horizon, like hanging them on a washing
                          > line. The yaw values are known and can be assigned manually. Just
                          > optimize p & r on the four images and they should line up perfectly,
                          > assuming your lens parameters are good. (Must use the Pano Tools
                          > optimizer for this, of course). Exclude the artificial horizon image
                          > via the Include Images list when you generate the output.
                          >
                          > John
                          >
                          >
                          >
                          > ------------------------------------
                          >
                          >
                        • Fabio Bustamante
                          Sacha, What do you mean with gravitational field of water? What does it have to do with leveling?
                          Message 12 of 30 , Oct 28, 2008
                          • 0 Attachment
                            Sacha,

                            What do you mean with gravitational field of water? What does it have to
                            do with leveling?

                            Sacha Griffin wrote:
                            > Honestly, in a situation where there is an actual Gravitational Field of
                            > water in all shots, and you can not level your 360.
                          • Fabio Bustamante
                            Hey Luca Yes, I ll try and upload this project. Will post the link soon.
                            Message 13 of 30 , Oct 28, 2008
                            • 0 Attachment
                              Hey Luca

                              Yes, I'll try and upload this project. Will post the link soon.

                              Luca N Vascon wrote:
                              > Fabio, post it and I'll fix it and than tell you.
                              > I'd use a template made with the same setup...
                              >
                              >
                              > Fabio Bustamante ha scritto:
                              >
                              >> Not the case, Sacha... I checked for it.
                              >>
                              >> Sacha Griffin wrote:
                              >>
                              >>> You probably have a vertical point set somewhere instead of a horizontal
                              >>> point.
                              >>>
                              >>
                              >>
                              >
                              >
                            • AYRTON
                              On Tue, Oct 28, 2008 at 12:59 PM, Fabio Bustamante
                              Message 14 of 30 , Oct 28, 2008
                              • 0 Attachment
                                On Tue, Oct 28, 2008 at 12:59 PM, Fabio Bustamante <
                                contato@...> wrote:

                                > The pano was made at sea, 5 km from the coast, over shallow reefs. The
                                > reefs were all covered with water but shallow enough to set the tripod
                                > firmly. Since there's water all around my only reference is the horizon,
                                > which is pretty featureless, by the way.



                                I've shoot on a similar situation. Just nt exactly 5 km ...

                                <http://ayrton.com/360/2007/08/10/go-deep/>

                                I've align it by hand at the Editor Window on ptgui

                                best
                                AYRTON



                                >
                                > Any hint will be appreciated!
                                >
                                > ------------------------------------
                                >

                                ------------
                                | A Y R |
                                | T O N |
                                ------------

                                + 55 21 9982 6313

                                http://ayrton360.com
                                http://rio.360cities.net
                                http://vrfolio.com
                                http://ayrton.com


                                [Non-text portions of this message have been removed]
                              • John Houghton
                                ... This is probably why you were unable to level your images. The optimizer will try to bring all the assigned t3 points into a straight line in the output
                                Message 15 of 30 , Oct 29, 2008
                                • 0 Attachment
                                  --- In PanoToolsNG@yahoogroups.com, Fabio Bustamante <contato@...>
                                  wrote:
                                  >
                                  > This is a great idea, John!
                                  >
                                  > Although I must confess I never clearly understood the function of
                                  > the t3 lines...

                                  This is probably why you were unable to level your images. The
                                  optimizer will try to bring all the assigned t3 points into a
                                  straight line in the output area. (Use t4 points on a different
                                  straight line feature, t5 points on another ....). You should only
                                  put the t3 points on a feature that ought to be rendered straight in
                                  the selected projection type. In an equirectangular projection, only
                                  the horizon and vertical lines are rendered straight. Water finds
                                  its own natural level and in your scene, the horizon will be a
                                  horizontal straight line passing through the centre of the output
                                  area. So putting t3 points on the horizon in each image will align
                                  the horizons along a straight line.

                                  You need two t3 points on each image, i.e. four marked points along
                                  the horizon (t3 points are not placed on identical features like
                                  ordinary control points). So display the same image in the two
                                  control point windows and assign two t3 pairs. Repeat for all four
                                  images. Take care to select cp type t3 each time - PTGui tends to
                                  reset it to t1.

                                  Optimizing only pitch and roll on all the horizontal shots should
                                  then align the images correctly. Using a background artificial image
                                  to peg the images to as I suggested ought not to be needed, but if
                                  all else fails try that too.

                                  John
                                • Jakob Norstedt-Moberg
                                  ... You have to take in account that the earth is round. The horizon will always be below the center of the equirectangular image. If your camera is two meters
                                  Message 16 of 30 , Oct 29, 2008
                                  • 0 Attachment
                                    --- In PanoToolsNG@yahoogroups.com, "John Houghton" <j.houghton@...>
                                    wrote:
                                    > ..., the horizon will be a
                                    > horizontal straight line passing through the centre of the output
                                    > area.

                                    You have to take in account that the earth is round. The horizon will
                                    always be below the center of the equirectangular image. If your
                                    camera is two meters above sea level the horizon (where sea and sky
                                    meet) will be offset slightly less than a pixel below the center of a
                                    6000x300 equirect. This is not much but at a 300meter high mountain
                                    the sea level will be about 9 pixels below the center which is
                                    noticable.

                                    There is a simple rule of thumb to calcualte this. Take the square
                                    root of the altitude in feet and you will have the approximate number
                                    of arc minutes the horizon is lowered. So 6 feet make 2.5 arc minutes
                                    which is 2.5/(180*60) of the full zenith to nadir arc distance. 1000
                                    feet make 33 arc minutes.

                                    By the way, this number of arc minutes the horizon is lowered is the
                                    same as the distance in nautical miles (1852 meters) to the horizon.

                                    Note that this is a rule of thumb. To calculate it exactly is just a
                                    matter of simle trigonometry.

                                    Jakob
                                  • Jakob Norstedt-Moberg
                                    ... It should of course be 6000x3000 equirectangular. jakob
                                    Message 17 of 30 , Oct 29, 2008
                                    • 0 Attachment
                                      --- In PanoToolsNG@yahoogroups.com, "Jakob Norstedt-Moberg" <jakob@...>
                                      wrote:
                                      > 6000x300 equirect.
                                      It should of course be 6000x3000 equirectangular.

                                      jakob
                                    • Jeffrey Martin
                                      oh my goodness. did someone tell you this, or did you figure it out yourself? and if you did, HOW did you figure this out? I m not really a good mathematician,
                                      Message 18 of 30 , Oct 29, 2008
                                      • 0 Attachment
                                        oh my goodness. did someone tell you this, or did you figure it out
                                        yourself? and if you did, HOW did you figure this out?

                                        I'm not really a good mathematician, maybe this is more obvious to
                                        other people. at any rate, it's fascinating :)



                                        Re: Hard time with horizon

                                        Posted by: "Jakob Norstedt-Moberg" jakob@... fotoverkstan

                                        Wed Oct 29, 2008 2:08 am (PDT)

                                        --- In PanoToolsNG@yahoogroups.com, "John Houghton" <j.houghton@...>
                                        wrote:
                                        > ..., the horizon will be a
                                        > horizontal straight line passing through the centre of the output
                                        > area.

                                        You have to take in account that the earth is round. The horizon will
                                        always be below the center of the equirectangular image. If your
                                        camera is two meters above sea level the horizon (where sea and sky
                                        meet) will be offset slightly less than a pixel below the center of a
                                        6000x300 equirect. This is not much but at a 300meter high mountain
                                        the sea level will be about 9 pixels below the center which is
                                        noticable.

                                        There is a simple rule of thumb to calcualte this. Take the square
                                        root of the altitude in feet and you will have the approximate number
                                        of arc minutes the horizon is lowered. So 6 feet make 2.5 arc minutes
                                        which is 2.5/(180*60) of the full zenith to nadir arc distance. 1000
                                        feet make 33 arc minutes.
                                      • Jakob Norstedt-Moberg
                                        ... It has always fascinated me. When I was sailing as a kid I was watching the land rise out of the horizon when approching. That made me start thinking about
                                        Message 19 of 30 , Oct 29, 2008
                                        • 0 Attachment
                                          --- In PanoToolsNG@yahoogroups.com, "Jeffrey Martin" <360cities@...>
                                          wrote:
                                          >
                                          > oh my goodness. did someone tell you this, or did you figure it out
                                          > yourself? and if you did, HOW did you figure this out?
                                          >
                                          It has always fascinated me. When I was sailing as a kid I was watching
                                          the land rise out of the horizon when approching. That made me start
                                          thinking about how far away the horizon really is.

                                          I don't know if the rule of thumb is of common knowledge; I "invented"
                                          it as a teenageer several decades ago. But it should be pretty obvious
                                          for sailors with mathematical knowledge so I doubt I was the first to
                                          construct it.

                                          Jakob
                                        • crane@ukonline.co.uk
                                          ... my literal rule of thumb to find out how far off shore I was when out fishing was to hold thumb out in front of me and open and close alternate eyes.
                                          Message 20 of 30 , Oct 29, 2008
                                          • 0 Attachment
                                            Quoting Jakob Norstedt-Moberg <jakob@...>:

                                            > --- In PanoToolsNG@yahoogroups.com, "Jeffrey Martin" <360cities@...>
                                            > wrote:
                                            > >
                                            > > oh my goodness. did someone tell you this, or did you figure it out
                                            > > yourself? and if you did, HOW did you figure this out?
                                            > >
                                            > It has always fascinated me. When I was sailing as a kid I was watching
                                            > the land rise out of the horizon when approching. That made me start
                                            > thinking about how far away the horizon really is.
                                            >
                                            > I don't know if the rule of thumb is of common knowledge; I "invented"
                                            > it as a teenageer several decades ago. But it should be pretty obvious
                                            > for sailors with mathematical knowledge so I doubt I was the first to
                                            > construct it.

                                            my literal "rule of thumb" to find out how far off shore I was when out
                                            fishing was to hold thumb out in front of me and open and close alternate
                                            eyes. then I was 9 times out ( I think, i'd have to work it out again) times
                                            the distance my thumb spanned on shore.
                                            regards

                                            mick


                                            > Jakob
                                            >
                                            >
                                            > ------------------------------------
                                            >
                                            > --
                                            >
                                            >
                                            >
                                            >




                                            ----------------------------------------------
                                            This mail sent through http://www.ukonline.net
                                          • michel thoby
                                            Jeffrey, Jakob et all haven t tell us the complete truth. From 400 km of altitude, the horizon appears definitely bent: It s a circle that surrounds the ISS
                                            Message 21 of 30 , Oct 29, 2008
                                            • 0 Attachment
                                              Jeffrey,

                                              Jakob et all haven't tell us the complete truth.
                                              From 400 km of altitude, the horizon appears definitely bent: It's a
                                              circle that surrounds the ISS and the astronaut who looks at the
                                              Nadir (i.e. looking down vertically).
                                              This circle of the horizon looks even smaller when seen from the
                                              surface of the moon almost 400 000 km away.

                                              This is just to make you aware that while Jakob is right when he told
                                              us the horizon is below the center of the equirectangular image, it
                                              shall also never be not really a straight line on the rectilinear
                                              projection!
                                              Well, generally you can't see the difference until the shooting is
                                              done from a high-flying vehicle...
                                              BTW you wont either realize this fact when the horizon is hidden by
                                              clouds: http://www.panoramas.re/AERIEN/index.htm;-)

                                              Michel

                                              Le 29 oct. 08 à 10:25, Jeffrey Martin a écrit :

                                              > oh my goodness. did someone tell you this, or did you figure it out
                                              > yourself? and if you did, HOW did you figure this out?
                                              >
                                              > I'm not really a good mathematician, maybe this is more obvious to
                                              > other people. at any rate, it's fascinating :)
                                              >
                                              > Re: Hard time with horizon
                                              >
                                              > Posted by: "Jakob Norstedt-Moberg" jakob@... fotoverkstan
                                              >
                                              > Wed Oct 29, 2008 2:08 am (PDT)
                                              >
                                              > --- In PanoToolsNG@yahoogroups.com, "John Houghton" <j.houghton@...>
                                              > wrote:
                                              > > ..., the horizon will be a
                                              > > horizontal straight line passing through the centre of the output
                                              > > area.
                                              >
                                              > You have to take in account that the earth is round. The horizon will
                                              > always be below the center of the equirectangular image. If your
                                              > camera is two meters above sea level the horizon (where sea and sky
                                              > meet) will be offset slightly less than a pixel below the center of a
                                              > 6000x300 equirect. This is not much but at a 300meter high mountain
                                              > the sea level will be about 9 pixels below the center which is
                                              > noticable.
                                              >
                                              > There is a simple rule of thumb to calcualte this. Take the square
                                              > root of the altitude in feet and you will have the approximate number
                                              > of arc minutes the horizon is lowered. So 6 feet make 2.5 arc minutes
                                              > which is 2.5/(180*60) of the full zenith to nadir arc distance. 1000
                                              > feet make 33 arc minutes.



                                              [Non-text portions of this message have been removed]
                                            • Jakob Norstedt-Moberg
                                              ... It depends on what projection you use internally in your mind. ;)
                                              Message 22 of 30 , Oct 29, 2008
                                              • 0 Attachment
                                                --- In PanoToolsNG@yahoogroups.com, michel thoby <thobymichel@...>
                                                wrote:
                                                >
                                                > Jeffrey,
                                                >
                                                > Jakob et all haven't tell us the complete truth.
                                                > From 400 km of altitude, the horizon appears definitely bent:

                                                It depends on what projection you use internally in your mind. ;)
                                              • crane@ukonline.co.uk
                                                ... and the camera sensor should really be curved like the eye mick ... This mail sent through http://www.ukonline.net
                                                Message 23 of 30 , Oct 29, 2008
                                                • 0 Attachment
                                                  Quoting Jakob Norstedt-Moberg <jakob@...>:

                                                  > --- In PanoToolsNG@yahoogroups.com, michel thoby <thobymichel@...>
                                                  > wrote:
                                                  > >
                                                  > > Jeffrey,
                                                  > >
                                                  > > Jakob et all haven't tell us the complete truth.
                                                  > > From 400 km of altitude, the horizon appears definitely bent:
                                                  >
                                                  > It depends on what projection you use internally in your mind. ;)

                                                  and the camera sensor should really be curved like the eye

                                                  mick

                                                  ----------------------------------------------
                                                  This mail sent through http://www.ukonline.net
                                                • Chris Thomas
                                                  I think I was told at some point that the horizon is 28 miles distant. I ve often wondered if it was true.. Chris Thomas Photographer cell... 604-649-5352 In
                                                  Message 24 of 30 , Oct 29, 2008
                                                  • 0 Attachment
                                                    I think I was told at some point that the horizon is 28 miles distant.

                                                    I've often wondered if it was true..



                                                    Chris Thomas

                                                    Photographer

                                                    cell... 604-649-5352

                                                    In North America

                                                    call... 1-800-870-5110

                                                    <http://www.christhomas.com/> http://www.christhomas.com



                                                    -----Original Message-----
                                                    From: PanoToolsNG@yahoogroups.com [mailto:PanoToolsNG@yahoogroups.com] On
                                                    Behalf Of crane@...
                                                    Sent: Wednesday, October 29, 2008 4:25 AM
                                                    To: PanoToolsNG@yahoogroups.com
                                                    Subject: Re: [PanoToolsNG] OT: Re: Hard time with horizon



                                                    Quoting Jakob Norstedt-Moberg <jakob@fotoverkstan.
                                                    <mailto:jakob%40fotoverkstan.se> se>:

                                                    > --- In PanoToolsNG@ <mailto:PanoToolsNG%40yahoogroups.com>
                                                    yahoogroups.com, michel thoby <thobymichel@...>
                                                    > wrote:
                                                    > >
                                                    > > Jeffrey,
                                                    > >
                                                    > > Jakob et all haven't tell us the complete truth.
                                                    > > From 400 km of altitude, the horizon appears definitely bent:
                                                    >
                                                    [Chris Thomas] snip




                                                    [Non-text portions of this message have been removed]
                                                  • Jakob Norstedt-Moberg
                                                    ... told ... Michel, I m sorry, I missed this part of your message the first time I read it. The horizon (sea/sky) is always a straight line in an
                                                    Message 25 of 30 , Oct 29, 2008
                                                    • 0 Attachment
                                                      --- In PanoToolsNG@yahoogroups.com, michel thoby <thobymichel@...>
                                                      wrote:
                                                      >
                                                      > This is just to make you aware that while Jakob is right when he
                                                      told
                                                      > us the horizon is below the center of the equirectangular image, it
                                                      > shall also never be not really a straight line on the rectilinear
                                                      > projection!

                                                      Michel,

                                                      I'm sorry, I missed this part of your message the first time I read it.

                                                      The horizon (sea/sky) is always a straight line in an equirectangular.
                                                      Even if you are far out in space and the earth is just a small ball
                                                      below you the earth/sky border will be a straight line on the
                                                      rectilinear. It will, as long as you orient it with nadir at the lower
                                                      edge. Compare with the mirrorball nadir cap.

                                                      Jakob
                                                    • Jakob Norstedt-Moberg
                                                      ... told ... Michel, I m sorry, I missed this part of your message the first time I read it. The horizon (sea/sky) is always a straight line in an
                                                      Message 26 of 30 , Oct 29, 2008
                                                      • 0 Attachment
                                                        --- In PanoToolsNG@yahoogroups.com, michel thoby <thobymichel@...>
                                                        wrote:
                                                        >
                                                        > This is just to make you aware that while Jakob is right when he
                                                        told
                                                        > us the horizon is below the center of the equirectangular image, it
                                                        > shall also never be not really a straight line on the rectilinear
                                                        > projection!

                                                        Michel,

                                                        I'm sorry, I missed this part of your message the first time I read it.

                                                        The horizon (sea/sky) is always a straight line in an equirectangular.
                                                        Even if you are far out in space and the earth is just a small ball
                                                        below you the earth/sky border will be a straight line on the
                                                        rectilinear. It will, as long as you orient it with nadir at the lower
                                                        edge. Compare with the mirrorball nadir cap.

                                                        Jakob
                                                      • michel thoby
                                                        Jakob, I wrote rectilinear on purpose... The mirror ball is seen as a sphere at the nadir of the rectilinear projection (e.g. QT viewer) when its horizon
                                                        Message 27 of 30 , Oct 29, 2008
                                                        • 0 Attachment
                                                          Jakob,

                                                          I wrote "rectilinear" on purpose...
                                                          The mirror ball is seen as a sphere at the nadir of the "rectilinear"
                                                          projection (e.g. QT viewer) when its "horizon" is a straight
                                                          horizontal line below the center on the equirectangular image.
                                                          Didn't you mix-up words when writing <<... the earth/sky border will
                                                          be a straight line on the rectilinear >>?

                                                          Michel


                                                          Le 29 oct. 08 à 13:33, Jakob Norstedt-Moberg a écrit :

                                                          > --- In PanoToolsNG@yahoogroups.com, michel thoby <thobymichel@...>
                                                          > wrote:
                                                          > >
                                                          > > This is just to make you aware that while Jakob is right when he
                                                          > told
                                                          > > us the horizon is below the center of the equirectangular image, it
                                                          > > shall also never be not really a straight line on the rectilinear
                                                          > > projection!
                                                          >
                                                          > Michel,
                                                          >
                                                          > I'm sorry, I missed this part of your message the first time I read
                                                          > it.
                                                          >
                                                          > The horizon (sea/sky) is always a straight line in an equirectangular.
                                                          > Even if you are far out in space and the earth is just a small ball
                                                          > below you the earth/sky border will be a straight line on the
                                                          > rectilinear. It will, as long as you orient it with nadir at the lower
                                                          > edge. Compare with the mirrorball nadir cap.
                                                          >
                                                          > Jakob



                                                          [Non-text portions of this message have been removed]
                                                        • Jakob Norstedt-Moberg
                                                          ... the rectilinear ... Yes, I mixed it up. I was in a hurry. /Jakob
                                                          Message 28 of 30 , Oct 29, 2008
                                                          • 0 Attachment
                                                            --- In PanoToolsNG@yahoogroups.com, michel thoby <thobymichel@...>
                                                            wrote:
                                                            >
                                                            > Jakob,
                                                            >
                                                            > I wrote "rectilinear" on purpose...
                                                            > The mirror ball is seen as a sphere at the nadir of
                                                            the "rectilinear"
                                                            > projection (e.g. QT viewer) when its "horizon" is a straight
                                                            > horizontal line below the center on the equirectangular image.
                                                            > Didn't you mix-up words when writing <<... the earth/sky border will
                                                            > be a straight line on the rectilinear >>?
                                                            >
                                                            > Michel
                                                            >
                                                            Yes, I mixed it up. I was in a hurry. /Jakob
                                                          • RomualdV
                                                            Hi Michel and all, http://tinyurl.com/5eh5jy For this one I was on a Lagrange point ;-) Romuald
                                                            Message 29 of 30 , Oct 29, 2008
                                                            • 0 Attachment
                                                              Hi Michel and all,

                                                              http://tinyurl.com/5eh5jy
                                                              For this one I was on a Lagrange'point ;-)


                                                              Romuald

                                                              Le 29 oct. 08 à 14:26, michel thoby a écrit :

                                                              >
                                                              > Jeffrey,
                                                              >
                                                              > Jakob et all haven't tell us the complete truth.
                                                              > From 400 km of altitude, the horizon appears definitely bent: It's a
                                                              > circle that surrounds the ISS and the astronaut who looks at the
                                                              > Nadir (i.e. looking down vertically).
                                                              > This circle of the horizon looks even smaller when seen from the
                                                              > surface of the moon almost 400 000 km away.
                                                              >
                                                              > This is just to make you aware that while Jakob is right when he told
                                                              > us the horizon is below the center of the equirectangular image, it
                                                              > shall also never be not really a straight line on the rectilinear
                                                              > projection!
                                                              > Well, generally you can't see the difference until the shooting is
                                                              > done from a high-flying vehicle...
                                                              > BTW you wont either realize this fact when the horizon is hidden by
                                                              > clouds: http://www.panoramas.re/AERIEN/index.htm;-)
                                                              >
                                                              > Michel
                                                              >
                                                              > Le 29 oct. 08 à 10:25, Jeffrey Martin a écrit :
                                                              >
                                                              >> oh my goodness. did someone tell you this, or did you figure it out
                                                              >> yourself? and if you did, HOW did you figure this out?
                                                              >>
                                                              >> I'm not really a good mathematician, maybe this is more obvious to
                                                              >> other people. at any rate, it's fascinating :)
                                                              >>
                                                              >> Re: Hard time with horizon
                                                              >>
                                                              >> Posted by: "Jakob Norstedt-Moberg" jakob@... fotoverkstan
                                                              >>
                                                              >> Wed Oct 29, 2008 2:08 am (PDT)
                                                              >>
                                                              >> --- In PanoToolsNG@yahoogroups.com, "John Houghton" <j.houghton@...>
                                                              >> wrote:
                                                              >>> ..., the horizon will be a
                                                              >>> horizontal straight line passing through the centre of the output
                                                              >>> area.
                                                              >>
                                                              >> You have to take in account that the earth is round. The horizon will
                                                              >> always be below the center of the equirectangular image. If your
                                                              >> camera is two meters above sea level the horizon (where sea and sky
                                                              >> meet) will be offset slightly less than a pixel below the center of a
                                                              >> 6000x300 equirect. This is not much but at a 300meter high mountain
                                                              >> the sea level will be about 9 pixels below the center which is
                                                              >> noticable.
                                                              >>
                                                              >> There is a simple rule of thumb to calcualte this. Take the square
                                                              >> root of the altitude in feet and you will have the approximate number
                                                              >> of arc minutes the horizon is lowered. So 6 feet make 2.5 arc minutes
                                                              >> which is 2.5/(180*60) of the full zenith to nadir arc distance. 1000
                                                              >> feet make 33 arc minutes.
                                                              >
                                                              >
                                                              >
                                                              > [Non-text portions of this message have been removed]
                                                              >
                                                              >
                                                              > ------------------------------------
                                                              >
                                                              > --
                                                              >
                                                              >
                                                              >
                                                              >
                                                            • Bernhard Vogl
                                                              ... http://technology.newscientist.com/article/dn14477 ;-) Bernhard
                                                              Message 30 of 30 , Oct 29, 2008
                                                              • 0 Attachment
                                                                > and the camera sensor should really be curved like the eye
                                                                >
                                                                >
                                                                http://technology.newscientist.com/article/dn14477

                                                                ;-)

                                                                Bernhard
                                                              Your message has been successfully submitted and would be delivered to recipients shortly.