How to convert different lidar data formats to raster DTM and measure its geographic position accuracy?

Question

I'm trying to generate a DTM from lidar data and I'm new in the this field.

I have different kind of files which describe the same area (different versions):

• *.dtm
• *.xyz
• *.xyz with variable grid width (1 to 4 meter), according to the information sheet I have.

How would you handle each file format to get a DTM? Specially in the case of the XYZ-data with variable grid width, I have no idea about what to do.

Once you have the DTM, how can I be sure about the correct geographic position of the DTM?

I want to use the DTM to analyse the terrain. Which kind of format (of the DTM) would you recommend?

I use ArcGIS (with extensions) and would prefer a solution process on this platform. However, if there is an open source solution it's fine too.

Answer 1

ArcGIS solutions:

Convert the x,y,z data to a feature class then:

1. Build a TIN using x,y,z data and then convert this to a raster.

2. Interpolate the x,y,z to raster.

3. Use Anudem (topo2raster) to create a DEM.

4. Convert point to raster and just set a cell size that is suitable for your x,y,z data (usually only for dense data).

I would output a GeoTiff.

x,y,z can be gridded hence you can use gdal and just convert to another format such as GTIff.
x,y,z can just be point data then use 1,2,3 or 4 above or GDAL Grid.

The position should be fine as you have x and y. You just need to know the coordinate system. You can usually tell this by looking at the numbers in the x,y column and knowledge of your local area.

I would be remiss not to point you to this question as well.