I try to reproduce this visual effect without success (see forest.jpg)
The idea would be to create a color gradient to visualize the height of the trees, regardless of their altitude.
I created a tree with an uvw planar which works if the tree is not modified in forest. But if I apply the scale transform, the uvw is also changed and I get the following result (see forest_render.jpg)
Do you have an idea to achieve the desired result?
Thank you for your help