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Topic: focal length

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tksharpless (8 months ago)
Uploaded a set of jpegs having no focal length in exif (because taken with a manual lens) and rightly got some left out of synth with message "We couldn't determine their focal length. Preserve EXIF information in your photos before uploading them". So I added correct Focal Length to EXIF and uploaded again -- and got same message.  
Does this mean that photosynth depends on some other tag; if so, what?
dddExperiments (8 months ago)
The estimation of the focal length is a hacky process involving several try/error iterations, using:
1) 35mm focal equivalent
2) focal length + camera in photosynth ccd database (by checking the camera model+maker)
3) focal length + other exif fields to try to estimate ccd size...

So I guess that you don't have a 35mm focal length in your Exif data and your camera is not in the photosynth synther database. Can you try to upload again with a 35mm focal length? If you still have the same message can you share the source images?

tksharpless (8 months ago)
The camera is a Sony ILCE-7R (a7r).  If that is not in your database, it should be.  The metadata in the jpegs includes the ResolutionUnit, FocalPlaneXResolution and FocalPlaneYResolution tags as well as Focal Length; which is sufficient to determine the focal length in pixels.  And is in fact the preferred way to do that, when present, since the stated 35mm equivalent focal length is often wrong (I speak as a developer of photo software).  If Photosynth does not know how to use those tags, you should fix that.  Meanwhile, I shall try again with 35mm equiv.
tksharpless (8 months ago)
OK, no error message about focal length this time.  But it omitted the same 7 (of 26) photos, claiming it could not find corresponding points.  There is actually plenty of overlap, but that is understandable given the constantly changing neon nature of the scene.  I'd try once more with b/w images, if I thought I could then apply the result as a template to the color ones.
dddExperiments (8 months ago)
FYI what you are describing is actually what is happening in option 3). So I don't know why it's not working in your case (assuming that you are providing all these fields correctly). Note that the upload page is not exactly doing the same check. Thus the upload page may display a warning but the synther might be just fine.
Nathanael (8 months ago)
tksharpless, I'm not sure what the score on Photosynth 2's synther is (perhaps Henri or Sudipta could let us know) but in Photosynth 1 color was irrelevant to matching.

See Tony Ernst's reply here:
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