We have created multiple merged projects from two to three flights and always when we merge them there is a great amount of “noise” introduced to the DSM. This noise is not visible in a single project only when the projects are merged together. This makes the DSM quite useless and we have no idea how to resolve this or what causes this noise. The area is only partly noisy and the outlines of the noisy areas are very sharp and we are quite sure that the noise is only introduces in the merged project and not in the initial project.
Has anyone here experienced any problem like this before and does anyone know what the could be causing this?
The noise causes even terrain to look extremely rough. This noise is only visible in the DSM but not the point cloud or the mesh. This noise is very well visible on the orthomosaic as well. Therefore that makes me belive that this noise is introdcued in the third processing step.
Any help appreciated!
Hi, do you have as well noise if you process fully on of the individual projects and not the merged?
It may be that there is not good overlap between projects, so you can create manual tie points in the intersections between the different flights, do it in the the individual projects and use the same name in the all the projects where the point appears, process step 1 on each one and then merge.
Using GCPs as well help.
Strange it comes only in the DSM and not in the point cloud, since the DSM is obtained form the point cloud…
Hi.
I had the same problem! But the thing is that there is noise in the point cloud you probably just have not noticed it yet. A way you can view this noise is tilting the point cloud at such an angle where by you can almost look beneath it. You will see that the noise is caused because the projects merged in these specific areas have not merged properly and you would be looking at a second point cloud just under the one you have. I fixed the problem by loading all the images into one project and then by moving on to the next processes from there. But obviously if your project is too big then another option is to create manual tie points from the initial stage within your project before actually merging them. That way your tie points will be forced to tie in the point clouds together. And then create additional manual tie points after you have re-matched and optimized your project sort of like to tie in all the projects together and to create more matches for your point cloud.
Thank you! By adding MTP solved my problem but it takes a huge amount of time to add enough MTP to reduce the noise. It is also true that the noise is visible in the point cloud just did not notice it before.