In this Grasshopper Pufferfish example file you can learn how to generate the isolines of a mesh by cutting it with a plane.
Quad Swords - free addon for cutting mesh into grids - Released
Trim Mesh Isolines
Hydrus
700+ Isoline Stock Illustrations, Royalty-Free Vector Graphics
A trimmed QS mesh generated by cutting a regular background QS
Isolines setup
Plane cut
Mesh trim/split in Rhino Easiest method!
To Construct a Mesh Element From Contours
Quad Swords - free addon for cutting mesh into grids - Released
Rhino How To Trim Mesh
Free example files