DEM – Generating DEMs from Point Clouds and Differencing Them

Question

I have two point clouds obtained via structure from motion (ground photos of sand-dunes + Visual SfM/Agisoft Photoscan).

If I wanted to generate a DEM from these point clouds and difference them to look at elevation/sediment change, how would I go about doing this?

Is there any free software that can achieve this easily? I am a beginner at using GIS software.

At the moment I am using the free trial of Agisoft Photoscan, which can export the point cloud in Wavefront OBJ, Stanford PLY, XYZ text file, U3D, ASPRS LAS, and PDF formats.

Answer 1

You want to generate DEMs from point clouds, and then, compare such DEMs.

The following posts have examples using free software:

1. Generating DEMs from point clouds:

   • Determining bare earth DEM from unclassified LAS file? (MCC-LiDAR)
   • Creating DEM from LAS file without using LAStools (Fusion/QGIS; pktools/libLAS)
   • Converting LiDAR data to raster (DEM/DSM) for ArcGIS input? (ArcGIS; LAStools)

2. Comparison of DEMs:

   • Comparing two Digital Elevation Models (DEMs) from LAS files? (R)
   • How to compare accuracy of two DEM using GRASS (GRASS)
   • How to compare two DEMs and show their difference? (QGIS)