Taking forever to shade a ToNURBS model

Hi dear all , I am struggling for the same reason
polisrf generated from subd objects with high nr. of faces is behaving as follow :

  • not possible to shade it in RH7 ,taking forever
  • not possible to shade in RH 6 , taking forever
  • possible to shade it in RH 5 in a decent time
  • ( just for your reference instant shading despite high number of faces if i export it to catia through step )

I hope this will be fixed asap cause it is making workflow very hard in some case

many thnaks in advance , KR

Hi -

I’ve moved this to a new topic from a 6-year-old thread.
Could you please post a model that performs like this on your system and run the Rhino SystemInfo command and copy-paste the result here?

HI Wim , here is the result

Rhino 7 SR0 2020-10-27 (Rhino 7 BETA, 7.0.20301.12003, Git hash:master @ 4c0b73af74d105119977b2e4ef0738d956e83af0)
License type: Commercial, build 2020-10-27
License details: Stand-Alone
Expires on: 2020-12-11

Windows 10.0 SR0.0 or greater (Physical RAM: 16Gb)

Non-hybrid graphics.
Primary display and OpenGL: NVIDIA Quadro P400 (NVidia) Memory: 2GB, Driver date: 6-3-2019 (M-D-Y). OpenGL Ver: 4.6.0 NVIDIA 431.02

OpenGL Settings
Safe mode: Off
Use accelerated hardware modes: On
Redraw scene when viewports are exposed: On

Anti-alias mode: 4x
Mip Map Filtering: Linear
Anisotropic Filtering Mode: Height

Vendor Name: NVIDIA Corporation
Render version: 4.6
Shading Language: 4.60 NVIDIA
Driver Date: 6-3-2019
Driver Version:
Maximum Texture size: 32768 x 32768
Z-Buffer depth: 24 bits
Maximum Viewport size: 32768 x 32768
Total Video Memory: 2 GB

Rhino plugins that do not ship with Rhino

Rhino plugins that ship with Rhino
C:\Program Files\Rhino WIP\Plug-ins\SolidTools.rhp “SolidTools”
C:\Program Files\Rhino WIP\Plug-ins\Commands.rhp “Commands” 7.0.20301.12003
C:\Program Files\Rhino WIP\Plug-ins\rdk.rhp “Renderer Development Kit”
C:\Program Files\Rhino WIP\Plug-ins\RhinoRenderCycles.rhp “Rhino Render” 7.0.20301.12003
C:\Program Files\Rhino WIP\Plug-ins\RhinoRender.rhp “Legacy Rhino Render”
C:\Program Files\Rhino WIP\Plug-ins\rdk_etoui.rhp “RDK_EtoUI” 7.0.20301.12003
C:\Program Files\Rhino WIP\Plug-ins\rdk_ui.rhp “Renderer Development Kit UI”
C:\Program Files\Rhino WIP\Plug-ins\NamedSnapshots.rhp “Snapshots”
C:\Program Files\Rhino WIP\Plug-ins\export_STEP.rhp “STEP Export”
C:\Program Files\Rhino WIP\Plug-ins\RhinoCycles.rhp “RhinoCycles” 7.0.20301.12003
C:\Program Files\Rhino WIP\Plug-ins\Toolbars\Toolbars.rhp “Toolbars” 7.0.20301.12003
C:\Program Files\Rhino WIP\Plug-ins\3dxrhino.rhp “3Dconnexion 3D Mouse”
C:\Program Files\Rhino WIP\Plug-ins\Displacement.rhp “Displacement”


Hello - my guess is there is one , or a few, objects that are giving the mesher a hard time - if you can isolate half the model, at a time, ClearAllMeshes, Shade, and see if you can identify the culprits or narrow it down. Feel free to post the model or send to tech@mcneel.com (if confidential) , with a link back here in your comments - it will be easier to help with the file in hand.


thanks for the answers Wim and Pascal

I treid to upload here but its too heavy , I have sent you the file through wetransfer by using tech@mcneel.com

looking forward to your analysis

ps: I am conscious that the file is a bad example of modeling and subd use but it was useful in order to enphatize the reported shading problem


Hi Ivan - the object has 25,000 surfaces - it does indeed take a very long time to generate render meshes at the current file settings - and the mesh has about a million faces… Each face has to be meshed, which I guess is where the hang-up is.

It would be much more useful to have an example that is not specifically designed to be slow…


HI Pascal and thanks for your analysis

you are right and i know how much of a bad example this is when it comes to sub d use

I am conscious about that but when there is not time and when , like this case , i am driven by need to arrange a very quick pseudo reverse of an imported brep to be used for quick design of temporary jig such a technique can help me get the job done decently and quickly.

its a pity to be locked by the lack of performance , or maybe by the unnecessary high shading quality of rhino.

I wonder , being very easy to create "monsters " like the one sent to you when using subd ; being this technique a decent solution when the job need be arranged in zero time; isnt’ it time to think about adding a raw shading option to be activitated automatically when nr. of faces overcome a critic limit.
this would allow users to keep working wo being slowen down by graphic interface calculation timing.

BTW the same model is easily manageable in catia and also free cad

…there is no doubt that rhino shading mode is way better that those software but to me most important thing is not to slow donw my work flow.

I will try to adjust shading option as suggested by your amazing tech support but i think the automatic raw shading option could avoid lot of imprecations :stuck_out_tongue:

thanks for thinking about it



just a message to report once again that the potentiallity of RH7 on speed modelling are somehow thwarted up by the time wasted to wait for shading update after each modification.

having a cad with incredible potential and waste minutes to stare at screen in the hope shaded view will update is getting very annoying especially when you are sharing screen with customers and you are trying to discuss how to move forward.

the only chance i have so far is working in wireframe but its such a contradditions.

Point is that , as i keep reporting , other cads ( even opesource ) despite having a very poor shading mode are allowing me to shade same geometry quickly.

I am not a programmer but i keep wondering if McNeel cannot consider that chance to add a rough shade that mimic freecad or similar mode for those running rhino in machines with limited graphic performances.


You can probably do that yourself by modifying your display mesh settings and/or your display modes. In my experience however, if you are having trouble shading a particular model, there is most often a bad object somewhere that is proving hard for Rhino to create a display mesh for.