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Re: [yws-maps] Yahoo Simple Map API- PNG->GIF change sometime in he last 24 hours

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  • jeff@kalikstein.com
    I did get my terminology mixed a bit. To clarify, I m talking about the Map Image API . It s pretty clear to me now that the map projections have
    Message 1 of 6 , May 17, 2007
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      I did get my terminology mixed a bit. To clarify, I'm talking about the 'Map Image API'. It's pretty clear to me now that the map projections have changed...Is there any reference material you can point me to that documents this? I need to be able to convert lat/lng coords to pixel coordinate on a map tile returned by the map image api. You actually helped me with this int he past (see http://tech.groups.yahoo.com/group/yws-maps/message/1037), and was happily chugging along until yesterday.

      Thanks for your help.

      -jeff




      ----- Original Message ----
      From: Alan Brown <adbrown@...>
      To: yws-maps@yahoogroups.com
      Sent: Wednesday, May 16, 2007 10:06:30 PM
      Subject: RE: [yws-maps] Yahoo Simple Map API- PNG->GIF change sometime in he last 24 hours

      You mean the map image api (for request a simple map image), not the simple
      api (our term for GeoRSS display on top of a map)?

      If you mean the map image api, I can see that gifs are being returned
      regardless of whether you specify "gif" or "png". This is probably some
      sort of simple oversight. It's ironic, because for our "dial-up" maps, we
      just switched from using gifs to PNGs as the preferred format.

      We've just totally upgraded the backend, so, yes, the map style and software
      to render that map have completely changed. I'll pass the information about
      the GIF/PNG discrepancy to the appropriate people.

      -Alan

      _____

      From: yws-maps@yahoogroup s.com [mailto:yws-maps@yahoogroup s.com] On Behalf
      Of runningblogger
      Sent: Wednesday, May 16, 2007 6:43 PM
      To: yws-maps@yahoogroup s.com
      Subject: [yws-maps] Yahoo Simple Map API- PNG->GIF change sometime in he
      last 24 hours

      It appears that sometime with the last 24 hours, the Yahoo Map Simple
      API has changed from returning a reference to a PNG file to a GIF
      file. The online documentation for the API still states that a PNG
      reference will be returned by default, so this is either a bug or an
      undocumented change in behavior.

      BTW, this also appears to coincide with _different_ maps being
      returned as well- maps that appear to be of higher quality. However,
      I am not 100% sure that these are using the same map projections as
      the previous maps that were returned.

      I am excited to use the new higher quality maps, but concerned about
      this undocumented change, as it broke a feature in production.

      [Non-text portions of this message have been removed]




      [Non-text portions of this message have been removed]
    • Alan Brown
      ... that I have previously overlayed onto the maps correlating with streets, etc, no longer line up. At first glance, it looks as if the scale is slightly
      Message 2 of 6 , May 17, 2007
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        > First, it looks like the map projections have indeed changed. Route data
        that I have previously overlayed onto the maps correlating > with streets,
        etc, no longer line up.


        At first glance, it looks as if the scale is slightly different. The
        following is not *quite* authoritative, but it's my first impression at what
        has changed:

        Image type Previous MapImage Service New MapImage
        service

        GIF Dynamically generated Dynamically
        generated

        Cylindrical projection Mercator
        projection

        Scale same as dial-up map Scales same as
        dial-up map? (not sure)



        PNG Seamed tiles Dynamically
        generated

        Mercator projection Mercator
        projection

        Scales same as broadband map Scales same as
        dial-up map? (not sure)



        So, from what I'm seeing, using it's not a different projection per se, but
        a different scale . you might be able to adjust the numbers a little to get
        them to line up. It might make sense on our side to adjust the scales to
        match the tiled maps - there are many adjustments we're in the midst of
        making. I think your application is rather unique - I'm unaware of anyone
        else placing overlays on top of images generated by the mapimage api. I'll
        try to get back to you about this.

        Concerning the star - I'll pass that info on, again.

        -Alan





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      • Alan Brown
        Oops - it looks like yahoo groups is no respector of fonts and columns :-( Basically I set up a table, and the gist was that the old PNG map image service used
        Message 3 of 6 , May 17, 2007
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          Oops - it looks like yahoo groups is no respector of fonts and columns :-(

          Basically I set up a table, and the gist was that the old PNG map image
          service used Mercator projection, same scale as our tiled broadband maps,
          while the new service uses (I think) Mercator projection with slightly
          different scales. So, being nit-picky technical, the projection hasn't
          changed, but the scales have - slightly. (If anyone out there uses GIFs in
          a similar way, the projection *did* change, from cylindrical to Mercator).
          Some things are shifting around, and I'll see if they're willing to use the
          same scales as the tiled maps for the service; if not, some calibration will
          be needed on your side, and I'll pass on what knowledge I get.

          -Alan



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