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General / DEM-Manipulation along waterbodies
« on: March 17, 2025, 01:14:22 PM »
Hello everyone! I am a long time lurker, first time poster on this forum and have a question regarding DEM alteration for waterbodies. My apologies in advance in case this has been asked before - the forum search did not come up with anything similar.
The company i work for is often tasked with the creation of Orthomosaics and DEMs along rivers (= inclined plane).
Orthomosaics turn out great everytime, DEMs in combination with GCPs (precision under 3 cm) are great for land but expectedly vary a lot for the water-parts.
I know that it is possible to manipulate the DEM in postprocessing by creating polygons and the "edit DEM"-Button on rightclick.
My current workflow for the river is: take water levels with GPS every 100 m or so in the field. In Metashape i draw a polygon for every water level marker i have in a way that the polygons slightly overlap each other. I then select one polygon after the other, right click --> edit DEM and set that polygons height to the measured height. That way i get a somewhat inclined plane as water level.
This works fine for short stretches of a couple hundred meters, but is unfeasible for stretches of a few kilometers.
Is there any way to recalculate the DEM as an inclined plane with, say, 2 given points? That way i could take one water level at the start and one water level at the end of the project and just interpolate between these two points.
The DEM within the river does not have to be 100% accurate, i just want to get rid of all the mountains and valleys and have it somewhat accurate - best fit plane often puts the water level a couple of meters higher than it actually is because of all the distortion.
Thank you for reading, i am looking for your input!
The company i work for is often tasked with the creation of Orthomosaics and DEMs along rivers (= inclined plane).
Orthomosaics turn out great everytime, DEMs in combination with GCPs (precision under 3 cm) are great for land but expectedly vary a lot for the water-parts.
I know that it is possible to manipulate the DEM in postprocessing by creating polygons and the "edit DEM"-Button on rightclick.
My current workflow for the river is: take water levels with GPS every 100 m or so in the field. In Metashape i draw a polygon for every water level marker i have in a way that the polygons slightly overlap each other. I then select one polygon after the other, right click --> edit DEM and set that polygons height to the measured height. That way i get a somewhat inclined plane as water level.
This works fine for short stretches of a couple hundred meters, but is unfeasible for stretches of a few kilometers.
Is there any way to recalculate the DEM as an inclined plane with, say, 2 given points? That way i could take one water level at the start and one water level at the end of the project and just interpolate between these two points.
The DEM within the river does not have to be 100% accurate, i just want to get rid of all the mountains and valleys and have it somewhat accurate - best fit plane often puts the water level a couple of meters higher than it actually is because of all the distortion.
Thank you for reading, i am looking for your input!
