[Qgis-user] How to create 3d terrain from DEM?

[Andrea Giudiceandrea]

> greg at tekknow.net greg at tekknow.net
> Thu Feb 22 20:12:38 PST 2024

Hi Greg,
while I'm not sure that the IDW interpolation is the right interpolation 
algorithm to use in order to obtain a valid DEM from irregularly sampled 
elevation data and that Google Earth is a valid source of elevation data 
at sufficient resolution and precision for a house building, it looks 
like the main issue is due to the fact that the point vector layer 
containing the elevation data is in a geographical Coordinate Reference 
System, i.e. the unit of measure of the X and Y coordinates is the 
degree, while the unit of measure of the Z coordinate (elevation) is 
probably the metre.

Thus, in order for the the 3D terrain to be correctly displayed, you 
firstly need to reproject the point vector layer containing the 
elevation data to a projected Coordinate Reference System whose unit of 
measure for the X and Y coordinates is the metre and then use such 
reprojected point vector layer to create the DEM.
I suggest you to use an UTM projection suitable for your area.

Best regards.

Andrea