Flow along surface maintain original orientation

Hi, I’m fairly new to Rhino, and am having an issue with the flow along surface command. Basically I have a city plan that I want to apply to a topographical surface (made using the drape command). I’ve managed to do this successfully before, but for some reason when I try to flow the curves on the left onto the surface on the right:

The curves rotate 90 degrees and stretch to fit the surface.

I’ve tried the command with “rigid” on and off. Any idea why this is happening? Or any ideas on how I might achieve this using a different workflow?

Why do you want to Flow instead of just Project? --Mitch

I hadn’t heard of project, I thought flow would allow the plan to best assimilate how the city would work with the topo in real life. Would there be any distortion with project?

Well, I assumed the plan in 2d was a true plan view, in which case if you use Project, it will stay non-distorted when viewed from the top. If you use Flow along surface, it will get mapped along the surface instead of projected onto it, which will create distortion when viewed from the top if the surface you’re flowing to is not flat.

For Flow along surface, you need a “from” surface and a “to” surface. Also, it does not work with meshes as reference/target surfaces.

HTH, – Mitch