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

Re: Drum panorama (now: sensor reading)

Expand Messages
  • John Riley
    ... Now, THAT was a crazy ride! Reminds me of my younger days when a friend handed me something and said here, eat this , hehehe. You say Yes, of course ,
    Message 1 of 25 , Nov 2, 2011
    • 0 Attachment


      On Nov 2, 2011, at 6:20 PM, Erik Krause wrote:

      Am 02.11.2011 23:06, schrieb John Riley:
      > Thanks Erik, that's interesting. Is the sensor also read sequentially
      > when shooting photos?

      Yes, of course. But it is read after the physical shutter closed, so it 
      won't have any impact on the image.

      Video rolling shutter can give very strange effects, but it can be 
      positively used as well: http://www.youtube.com/watch?v=EnrwrwMfNSs


      Now, THAT was a crazy ride!  Reminds me of my younger days when a friend handed me something and said "here, eat this", hehehe.

      You say "Yes, of course", but are you sure about that?  I did a some looking around on the web and I get the impression that DSLRs only use (electronic) rolling shutter when shooting video, but read the whole sensor at once after the shutter closes with stills.

      Feel free to straighten me out, if need be.

      John

      John Riley
      4Pi-VR Media Solutions
      http://4pi-vr.com
      johnriley@...
      (h)864-461-3504
      (c)864-431-7075
      (w)864-503-5775
    • prague
      YOu might want to ask Igor Marx how he did this http://www.360cities.net/image/strawberry-panorama
      Message 2 of 25 , Nov 3, 2011
      • 0 Attachment
        YOu might want to ask Igor Marx how he did this

        http://www.360cities.net/image/strawberry-panorama




        --- In PanoToolsNG@yahoogroups.com, "Peter Stephens - PanoTools NG list" <panotoolsng@...> wrote:
        >
        > Hi Guys,
        >
        > I have been asked to produce a panoramic image of a drum, as if the drum was
        > sliced down on side and flattened. The idea is to produce a printable image
        > showing all areas of the cylinder at the same time.
        >
        > I have been experimenting with on of my own drums on an object turntable.
        > I've taken 16 images around it and have been playing around trying to
        > stitching it together. This particular drum hasn't a huge amount of detail
        > on it making it nearly impossible to generate control points in PTGui, so
        > not a great one to experiment with really. I suppose I could put some small
        > stickers around the outside of it which would help with stitching, might try
        > that later.
        >
        > I'm just wandering if any of you have done this before and have any advise
        > you can share with me? Cropping the 16 images into a thin strip and
        > manually stitching it with Photoshop has given me the best results so far,
        > though not of a quality high enough that I'm happy with. PTGui couldn't
        > generate control points, so didn't get anywhere with that. Expect I will
        > get better results with more images taken from different angles, but it's
        > going to take forever to process by hand. Would be great if I could do this
        > in PTGui.
        >
        > Any help would be appreciated.
        >
        >
        > Pete
        >
        > Peter Stephens Photography
        > www.peterstephens.co.uk
        > Follow me: <http://www.twitter.com/PJSPhotography> Twitter -
        > <http://www.facebook.com/PJSPhotography> Facebook -
        > <http://www.linkedin.com/in/PJSPhotography> Linkedin -
        > <http://www.flickr.com/peterstephensphotography> Flickr
        >
      • Peter Stephens - PanoTools NG list
        Cool !! gona have to give that a go now ! Pete Peter Stephens Photography www.peterstephens.co.uk From: PanoToolsNG@yahoogroups.com
        Message 3 of 25 , Nov 3, 2011
        • 0 Attachment

          Cool !!  gona have to give that a go now !

           

           

          Pete

          Peter Stephens Photography

          www.peterstephens.co.uk

           

          From: PanoToolsNG@yahoogroups.com [mailto:PanoToolsNG@yahoogroups.com] On Behalf Of prague
          Sent: 03 November 2011 09:53
          To: PanoToolsNG@yahoogroups.com
          Subject: [PanoToolsNG] Re: Drum panorama

           

           



          YOu might want to ask Igor Marx how he did this

          http://www.360cities.net/image/strawberry-panorama

          --- In PanoToolsNG@yahoogroups.com, "Peter Stephens - PanoTools NG list" <panotoolsng@...> wrote:
          >
          > Hi Guys,
          >
          > I have been asked to produce a panoramic image of a drum, as if the drum was
          > sliced down on side and flattened. The idea is to produce a printable image
          > showing all areas of the cylinder at the same time.
          >
          > I have been experimenting with on of my own drums on an object turntable.
          > I've taken 16 images around it and have been playing around trying to
          > stitching it together. This particular drum hasn't a huge amount of detail
          > on it making it nearly impossible to generate control points in PTGui, so
          > not a great one to experiment with really. I suppose I could put some small
          > stickers around the outside of it which would help with stitching, might try
          > that later.
          >
          > I'm just wandering if any of you have done this before and have any advise
          > you can share with me? Cropping the 16 images into a thin strip and
          > manually stitching it with Photoshop has given me the best results so far,
          > though not of a quality high enough that I'm happy with. PTGui couldn't
          > generate control points, so didn't get anywhere with that. Expect I will
          > get better results with more images taken from different angles, but it's
          > going to take forever to process by hand. Would be great if I could do this
          > in PTGui.
          >
          > Any help would be appreciated.
          >
          >
          > Pete
          >
          > Peter Stephens Photography
          > www.peterstephens.co.uk
          > Follow me: <http://www.twitter.com/PJSPhotography> Twitter -
          > <http://www.facebook.com/PJSPhotography> Facebook -
          > <http://www.linkedin.com/in/PJSPhotography> Linkedin -
          > <http://www.flickr.com/peterstephensphotography> Flickr
          >

        • Peter Stephens - PanoTools NG list
          Hi Scott, Thanks…. The drum I was experimenting with was only shot with 16 images so no wander I had issues with it….. also I shot it with an 75mm lens.
          Message 4 of 25 , Nov 3, 2011
          • 0 Attachment

            Hi Scott,

             

            Thanks….  The drum I was experimenting with was only shot with 16 images so no wander I had issues with it…..  also I shot it with an 75mm lens.  Will have another go with far more images and maybe a longer lens.  Loving the time machine photos, need to make some time to try to create some of these cool images.

             

            I’ll post my results here for you to see yes.

             

            Pete

             

            Peter Stephens Photography

            www.peterstephens.co.uk

             

            From: PanoToolsNG@yahoogroups.com [mailto:PanoToolsNG@yahoogroups.com] On Behalf Of Scott Highton
            Sent: 03 November 2011 00:16
            To: PanoToolsNG@yahoogroups.com
            Cc: Peter Stevens
            Subject: [PanoToolsNG] Re: Drum panorama

             

             

            Hi Peter,

             

            What you're trying to do is the equivalent of a slit scan camera shooting an object on a turntable, as I believe someone else mentioned here.  In general, the narrower the slit, the better your results (unless you go to extremes and then wind up with diffraction problems... don't worry about this for the following).  This sort of work has traditionally been done with slit scan camera/turntable systems such as those available from Roundshot (both film and digital) and Panoscan.

             

             

             

            You can try a similar approach with a low priced digital camera, a slow moving turntable, and some automated scripts (which you'll probably have to create) in Photoshop.

             

            Basically, you shoot a series of images as the object rotates, then extract a center column of pixels from each image, and then stack these columns together (like books in a book case) in Photoshop to create a complete 360° flattened view.  Don't try to "stitch" these columns, but rather, simply abut them next to each other.  The more pictures you take (i.e. the smaller the rotation between each), the fewer number of pixels you'll need to extract from the center of each, and the better your resulting image assembly is likely to be.

             

            In a perfect world, you'd only take a single pixel column from each image (the equivalent of a single pixel wide slit or image sensor), but that could entail capturing and extracting thousands of images.

             

            However, you may find that you can still get great results by shooting fewer images and extracting 10, 20, or 50 pixel wide columns from the center of each.  You'll have to do your own tests to see what works for the size of the object you're shooting and the resolution of the finished image you need.  And you'll have to figure out how many shots are necessary (how much to rotate the object between each shot) for a full rotation in order to maintain the proper aspect ratio for the resulting file when the columns are all stacked together.  Use a telephoto lens for best results.

             

             

            For example, let's say you want a final image that is 3,600 pixels wide.

             

            If you were only going to extract a single pixel column for each source image, you'd need 3,600 images, and you'd have to rotate the object 1/10 of a degree between shots.

            If you could use 10 pixel (wide) columns instead, you'd need only 360 images where the object was rotated one degree between shots.

            If you could use 20 pixel columns, you'd need 180 images where the object was rotated two degrees between shots.

            If you could use 50 pixel columns, you'd need 72 images where the object was rotated five degrees between shots.

            Or, if you could use 100 pixel columns, you'd need only 36 images where the object was rotated 10 degrees between shots.

            You see the pattern.

             

             

            Bryan Mumford, developer of the Time Machine camera triggering and time lapse system, has a web page that discusses this approach using his Time Machine, a motorized rotary table, and a digital camera.  The Time Machine controls the rotation of the rotary table and the firing of the camera.  He calls this process "Streak Photography," and he's created some beautifully artistic results, including sequences assembled into QT movies.  The same approach should work for capturing and assembling single "unwrapped" object images.

             

             

             

             

            Should you decide that you want to pursue a "stitching" approach instead, consider using a telephoto lens and shoot the object from a distance.  This will compress the differences between high and low points on the surface of the drum and minimize visual distortion or foreshortening of the object in each source image.  Then, enter a long focal length, such as 400mm, in PTGui (you may need to override the  EXIF lens info).  That might  better help with control point generation.

             

             

            Good luck with your efforts, and please let us know about your results (post them so we can see, if possible).

             

            Regards,

             

             

             

             

            Scott Highton

            Author, Virtual Reality Photography

                 320 pages, 300+ illustrations, $44.95

                 ISBN 978-0-615-34223-8)

            Web: http://www.vrphotography.com

             

          • Michel Thoby
            ... I had posted a page about what I think is a closely related matter. I have converted some QTVR old files to supplement them in Flash. Hoping it all works
            Message 5 of 25 , Nov 3, 2011
            • 0 Attachment

              Le 3 nov. 2011 à 10:53, prague a écrit :

              YOu might want to ask Igor Marx how he did this

              http://www.360cities.net/image/strawberry-panorama

              I had posted a page about what I think is a closely related matter. I have converted some QTVR old files to supplement them in Flash. Hoping it all works right:

              Michel
            • Erik Krause
              ... It isn t possible technically to read the whole sensor at once. You would need one A/D converter for each sensor cell, not to speak of the processor which
              Message 6 of 25 , Nov 3, 2011
              • 0 Attachment
                Am 03.11.2011 04:10, schrieb John Riley:
                > I get the impression that DSLRs only use (electronic) rolling shutter
                > when shooting video, but read the whole sensor at once after the shutter
                > closes with stills.

                It isn't possible technically to read the whole sensor at once. You
                would need one A/D converter for each sensor cell, not to speak of the
                processor which would need to run several million tasks in parallel. You
                can't even read all scan lines in parallel.

                read
                http://en.wikipedia.org/wiki/Active_pixel_sensor#Array
                and
                http://en.wikipedia.org/wiki/Charge-coupled_device#Frame_transfer_CCD

                However, since the physical shutter moves at limited speed you get a
                rolling shutter effect anyway. If you shoot at exposure times faster
                than shortest flash sync (1/250s usually) only a slit moves across the
                sensor. See f.e. http://www.youtube.com/watch?v=ptfSW4eW25g

                --
                Erik Krause
                http://www.erik-krause.de
              • prague
                then how does a Global Shutter work?
                Message 7 of 25 , Nov 4, 2011
                • 0 Attachment
                  then how does a Global Shutter work?



                  --- In PanoToolsNG@yahoogroups.com, Erik Krause <erik.krause@...> wrote:
                  >
                  > Am 03.11.2011 04:10, schrieb John Riley:
                  > > I get the impression that DSLRs only use (electronic) rolling shutter
                  > > when shooting video, but read the whole sensor at once after the shutter
                  > > closes with stills.
                  >
                  > It isn't possible technically to read the whole sensor at once. You
                  > would need one A/D converter for each sensor cell, not to speak of the
                  > processor which would need to run several million tasks in parallel. You
                  > can't even read all scan lines in parallel.
                  >
                  > read
                  > http://en.wikipedia.org/wiki/Active_pixel_sensor#Array
                  > and
                  > http://en.wikipedia.org/wiki/Charge-coupled_device#Frame_transfer_CCD
                  >
                  > However, since the physical shutter moves at limited speed you get a
                  > rolling shutter effect anyway. If you shoot at exposure times faster
                  > than shortest flash sync (1/250s usually) only a slit moves across the
                  > sensor. See f.e. http://www.youtube.com/watch?v=ptfSW4eW25g
                  >
                  > --
                  > Erik Krause
                  > http://www.erik-krause.de
                  >
                • Erik Krause
                  ... In still photography any non-focal-plane shutter is a global one. For video apparently CCD sensors don t suffer from rolling shutter (which was new to me):
                  Message 8 of 25 , Nov 6, 2011
                  • 0 Attachment
                    Am 04.11.2011 15:57, schrieb prague:
                    > then how does a Global Shutter work?

                    In still photography any non-focal-plane shutter is a global one. For
                    video apparently CCD sensors don't suffer from rolling shutter (which
                    was new to me): http://www.dvxuser.com/jason/CMOS-CCD/

                    --
                    Erik Krause
                    http://www.erik-krause.de
                  Your message has been successfully submitted and would be delivered to recipients shortly.