Hello,
I have been a Photoscan user for some time, but typically use older, course resolution imagery. I have recently received a set of about 300 high-resolution images collected from a helicopter. They were collected with a Nikon D3 camera and generally are very high quality. I have run through my typical workflow, which is:
1. Align photos on high
2. Run a low geometry model for quick verification
3. Insert ground control. Ground control for this project were collected by a professional survey crew and should be accurate to a few centimeters.
4. Adjust ground control marker in images to ensure markers are properly placed
5. Optimize model
6. Generate Medium heightfield model
7. Output Orthoimage and DEM (output resolution is 1.1cm on the ortho and 7cm on the DEM)
I have used 6 gcps spread throughout the image area and have about 10 reserved as check points. When I perform my accuracy analysis on the 10 check points, I get a horizontal CE95 of about 4.4cm. That is very good and certainly good enough for my application. However, when I run the analysis on the DEM, I get a LE95 of about 19cm. This is not as good as I would like and worse than I was expecting. Given other people's experience with high resolution imagery, is this a reasonable value for elevation error?
Also, would it help to run the model as high or ultrahigh? I typically don't see much advantage to doing this with the historic imagery, but perhaps it is more useful with high-resolution imagery.
Thanks,
Scott