Drape creates sagging in topography

[Signe_Lund_Jensen]

Hi,

I am making a surface from a mesh with drape, however, the surface comes out with significant “craters” or places in the surface where the topography sags down.

File: .3dm

I’m working in Rhino7 on a Macbook.

This is my workflow:

1. Create mesh from topography lines with grasshopper.
2. Reduce mesh 30%.
3. Drape, Auto Spacing: yes, Spacing: 1, Auto Detect Max Depth: Yes

I know drape can be a bit unreliable but I would like to get as close to the original mesh as possible.

Thank you in advance for any advice!

[theoutside (Kyle Houchens)]

to my eye, and from the images you shared, it looks like drape is doing what you are asking it to do…what different result are you hoping for? Can you clarify a bit?

what is the intent of the final output (printing, rendering, cnc machine etc? )

[Helvetosaur]

@Signe_Lund_Jensen

but I would like to get as close to the original mesh as possible.

Drape will not do that. If you reduce the sampling by going to manual spacing and specifying the number of U/V points, you can get a smoother drape that will not fall into the holes, but it will miss the mesh by much further in spots.

Possibly you could QuadRemesh the terrain mesh and then ToNurbs.