I flew many small catch basins in agriculture fields, approx 250square meters each. I need an accurate ground level to compare to previous years DSM (for sediment accumulation in the basin). The problem is, there is corn stalk from harvest throughout the field and in the basin to be measured. Corn stalks stick up 1-2 feet and are making the DSM inaccurate. Do I have to disable all the stalk by editing the point cloud, or is there another way?
Assuming you are able to generate points that represent the underlying terrain, you will then want to edit the point cloud and disable all of the points that are vegetation. This will let you create an accurate DTM. However, it is a very manual process and can be time consuming. You might want to try PIX4Dsurvey. Survey has a much more robust method for automatically classifying the points that are terrain. It should accomplish your goals much faster.
I have run into the same issue with standing corn stalks. I currently use the desktop version of Pix4D mapper. Is there any information on Pix4D survey I can view somewhere that would support the theory automatically classifying terrain points vs. vegetation?
You can check out this support article that describes the terrain filter in Survey.