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NAIP Imagery Accuracy
I hesitate to ask since it may turn out that the Romans had a solution, but I’m looking at some 2012 images from the National Agriculture Imagery Program and am wondering how others deal with the uncertainties in the pixel coordinates. The ultimate object is to extract positions of the banks of a river that show up quite well in the imagery and which would be good enough for certain purposes.
The images have 1m pixels and the horizontal accuracy of the rectification is claimed (in the accompanying metadata) to be “to a horizontal accuracy of within +/- 5 meters of reference digital ortho quarter quads DOQQ’s) from the National Digital Ortho Program (NDOP)” As I interpret that specification, it is just a statistical measure of the residuals of image coordinates when compared to DOQQ coordinates, not a statement about the absolute uncertainty of the positions of pixel coordinates in the image.
I’m thinking that getting actual survey coordinates of image features is warranted to test/verify the accuracy of the images and possibly to do some secondary rectification of the images. Is there a better way to improve/verify the accuracy of the NAIP images that the Romans knew about?
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