Orthorectify orthomosaic using DTM, not DSM?

Dear ODM community,

I’m new to ODM, and still playing around with the settings. I have a drone project over a forested area (normal grid mission), and when I produce my orthomosaic in ODM, the results are not very desirable. A ton of image warping, bending and some blur.

When i compared ODM ortho to PhotoScan otho, the results where similar. Both times (ODM and PhotoScan) the othomosaics were orthorectified using the calculated DSM. In PhotoScan, I filtered out and selected only ground points (from the point cloud) to produce a DTM, and used the DTM to orthorectified my orthomosaic, which produce superior results (in my case, over different trees with varying heights). No warping or bending.

I am guessing that i did not have sufficient points in my point cloud file to produce a well filled in DSM from which to orthorectify my mosaics (E.g. i had to do a structured flight to capture more photos at a angle, not nadir), which caused the warping and bending, because the program tried to interpolate the missing values?

So my question is, can you set up WebODM to produce both a DTM and DSM and produce a high quality orthomosaic rectified using the DTM, not the DSM?

Any advice would be appreciated.

we’re you ever able to get any information on this? I am a newer ODM user and this particular issue is driving me crazy.

Currently there’s no support for using the DTM; but have you tried --fast-orthophoto? It might achieve a similar result.

thank you for the answer. While it is not officially support. I was wondering if it would be possible to trick the program to use a DTM or a modified pointcloud? if you restart from orthophotos is there a sub processing folder that you could place a DTM or a modified point cloud in place of the DSM. And are the orthos created using just the point cloud or on a DEM?