Georeferenced Files - GeoRef
The georeferencing system produces zip files that contain various files. These zipped files are named using the convention of PhotoID-GeoreferenceMethod-Variations.FileType. The table below explains the Variations-FileType part of these.
File name endingExplanation
no_warp.tifThis is a GeoTIFF version of the photo that is unmodified (unwarped) in an image sense, but contains metadata header fields indicating the list of control/tie/correspondence points found for alignment and some alignment fit uncertainty measures. This version gives an end user all they'd need to create their own aligned image from the embedded control points.
warp.tifThis is a GeoTIFF version of the photo that is modified to be warped/aligned to a map. It does not contain a header with the list of tie points, but it contains fields with alignment fit measures.
no_warp_metadata.txtThis is a text file containing a formatted dump of the header fields present in the -no_warp.tif version.
warp_metadata.txtSame as no_warp_metadata.txt but instead corresponding to the -warp.tif version.
uncertainty-no_warp.tifThis is a special synthetic image (single channel floating point) where the number at each pixel represents the uncertainty (standard deviation) in meters we estimate for our fit at that pixel. This provides data to do automated analysis of the relative accuracy of our alignment at each pixel -- it will be more accurate near tie points, and worse further away.
uncertainty-warp.tifAnalogous to the uncertainty-no_warp.tif file, this is a warped/aligned version of the uncertainty image. It contains two floating point channels, the first is the uncertainty as in the unwarped version, and the second is a "mask" that is 0 where there is no uncertainty data (the warped image doesn't exist there) or 255 if there is.