Preparation

Exporting the 3D model, drawing the contour lines will be our goal. First we remove the trees and buildings from the original 3D.

Cleaning

Filling holes, removing trees and buildings creates holes. It can be filled with Metashape.

Retexturing, recreates a nice texture over the filled parts.

Exporting

Post-processing in Rhino-Grasshopper

We will show how to draw contour-line very easily with Grasshopper.

Import the mesh.

Then, Mesh to Quad mesh to SubD , Fill holes in SubD and finally QuadMesh

In Grasshopper

Input Mesh

Create a vertical line

Divide the line into distances with a Slider, so that it can be changed

Create planes from the divided line

Intersect with the Mesh

You get your contour lines

Add heights

By changing the number of planes, you get more presision

This is every 20cm

Interactive result

Will add colors depending to Heights. (Click on the image for a readable view).

It gives this nice result