Silent Crash without EXIF Data

[MikePelton]

Not an issue exactly but a red flag - if the images you pass to the training don't have a focal length in their EXIF data, training will crash silently. I hope this stops anyone else disappearing down the same rabbit hole!

[amoazeni75]

Hi,
Thanks for your guidance. How can we ensure that our training data, especially ".png" and ".jpg," have the focal length?

[MikePelton]

Hi and thanks for coming back - I quite forgot to say how marvellous the code is - many thanks indeed. If the pictures have been taken with a phone or consumer camera, the data's in there already, although it's worth noting that COLMAP strips it out when it makes copies of the photos, so the copied images under COLMAP's "dense" folder won't have it. Our images have already been through a number of processes that haven't propagated the EXIF data along the pipeline so for us it's missing! In general any image editor (GIMP etc) will list the EXIF data for a photo, and if the "focal length" and "35mm equivalent focal length" values aren't set, you can use freely available tools (for example exiftool) to set them. If you don't know what the focal lengths are, photogrammetry tools like COLMAP capture the data as part of the cameras' "intrinsics". Sometimes these are stored as a pixel value and EXIF needs them in mm, so you need to find out some details of the camera's sensor to know how wide a pixel is in mm and convert. I haven't dug into your code sufficiently to find the point where you could check as the images are loaded up, but I notice several files load the "TinyEXIF" header, so as you're loading images the calls are available to spot the missing EXIF field data and issue a warning. Hope this helps - thanks again for ADOP!