The surface display wrong after split

[xiix.xoox (Azure)]

I use Rhino V7.9, when I split the surface by curve the result shows wrong.

as.3dm (6.9 MB)

[Mahdiyar]

Have you tried increasing render mesh quality?
https://wiki.mcneel.com/rhino/meshfaqdetails

[xiix.xoox (Azure)]

Thank you. I try

[pascal (Pascal Golay)]

Hello - try render mesh settings like so:

-Pascal

[xiix.xoox (Azure)]

Thank @pascal . I Try