Snow - How to achieve a accurate DSM?

PIX4Dmapper PIX4Dmapper Questions/Troubleshooting
1

 Issue - Volume measurements of stockpiles are off by 5-10% (volume lower when measuring after a snowfall (about 2 inches) Images captured with drone. 

First project -  No snow. Capturing the images from 50m. Double grid mission and 80% overlap. Volume measurement result only 1,8% from previous traditional measurement method which were done with RTK-GPS.

Second project - About 2 inches of snow on the stockpile. Capturing the images from 100m. Single grid mission and 85% overlap. Volume measurement shows almost 10% less volume compared to the first project. 

Comments: I flew higher the second time since that the recommendation when the area is homogeneous. 

BTW, when I upload the same series of pictures to DroneDeploy the DSM looks better and the volume measurement is only 1-2% apart from previous measurement.

Questions:

  • Would the accuracy improve if the images are captured from a lower altitude?
  • Would double grid provide a higher detail of the DSM?
  • Are there some “tweaks” during processing in Pix4Dmapper which could improve accuracy?

DSM in first project. High level of detail. 

 

DSM from second project. Less detail. 

 

1 Like
2

Thing is that now the measurement is within 1% from previous measurement. What I did was to add two manuell tie points. Re-optimized. Could it be that simple? DSM still looks a bit strange. 

3

Hi Anders -

General rule is that “Snow = No Go”.  

You’ll want to externally verify results either way, but I definitely would not rely on the set with snow in it. Not a good situation for photogrammetry. 

4

What camera would you use for volumetrics in snow? Photo? RGB? Thermal? Laser?

5

I don’t believe LiDAR works well in the snow either, but I don’t have any experience with that.