FAQ: How to Georeference the UTM 3D Mesh using the Offset.txt file?

What is the offset.txt?

The UTM mesh files generated in DataHub are not georeferenced. It uses the (0,0,0) as its origin to avoid incompatibilities of large coordinate values with other 3D viewers.

The offset.txt file stores displacement values along the X, Y, and Z axes between the central points and the outputs' coordinate system which is UTM. The offset is computed as:

Arbitrary CRS - UTM CRS = Offset

 

 

How to use offset.txt in translating UTM meshes?

1. Retrieve the offset.txt from the File Manager.

2. Add the offset values to the existing coordinates.

UTM CRS = Arbitrary CRS + Offset

 

3. The UTM mesh should be now positioned correctly in the UTM coordinate system.

 

Adding the Offset via CloudCompare:

To manipulate the position of the downloaded UTM mesh in DataHub so that it will be projected into its correct position in UTM, you'll need to translate it using the offset values provided in offset.txt.

1. Open your OBJ file in Cloud Compare.

2. Make sure to select the desired OBJ file, then go to Edit>Apply transformation

 

3. Go to the Axis/Angle tab and then add the offset values available in the offset.txt file in the correct X Y Z Fields. In the below example, we are adding the following offsets:

X axis: 656059.00
Y axis: 5514553.00
Z axis: 1713.00

4. You might encounter an option to view the new mesh using smaller coordinates--this is fine as long as you preserve the global shift on save.

5. Export your newly created mesh and double-check the new coordinates.

 

 

If you have any questions, please reach out to support@skycatch.com.