EXIF data / metadata usage for generating orthophotos

[varadg]

Hi. Can someone educate me as to what EXIF data / metadata can / is used by Agisoft in the process of generating an orthophoto from aerial images? I expect it would be helpful to have information about the focal length, camera calibration parameters, geolocation data etc. Can someone provide a comprehensive list?

[rossnixon]

As far as I know, just the following:
• focal length
• absolute pixel size on sensor
• longitude & latitude (just for initial alignment; then use GCPs)

[Alexey Pasumansky]

Hello varadg,

PhotoScan reads the following EXIF tags:
FocalLength - that is put to the corresponding field of the Camera Calibration window. Whereas for the Sensor Pixel Size uses either a pair of the following tags:
FocalPlaneXResolution and FocalPlaneYResolution, or if they are missing, uses the next one: FocalLengthIn35mmFilm.
The parameters mentioned above are used to define the initial values for the autocalibration procedure.

Also GPS tags are read:
GPSAltitude, GPSLatitude and GPSLongitude.

Additionally, optionally PhotoScan can read the camera orientation and location accuracy information from the XMP meta-data.

[varadg]

Thanks Alexey. So, if this information is provided within the EXIF data for all images, I assume it will speed up the computation process?

Also, currently, I have the Lat/Long/Alt & FocalLength available. However, it is not embedded as EXIF in the images and exists as a separate stream. Is it possible to use the API to use this data separately for the corresponding images during the alignment phase. Or is it possible to write code to embed this as EXIF data separately into each image? Are there any tools you can suggest for the same?

[rossnixon]

exiftool (freeware) can read/write EXIF data. See http://rz.scale-it.pl/2012/01/02/how_to_add_gps__geolocation__tags_to_photos.html