# Cant Render Subd Surface
**URL:** https://forum.highend3d.com/t/cant-render-subd-surface/45672
**Category:** Maya
**Tags:** mental-ray
**Created:** [February 18, 2007, 8:06am UTC](https://forum.highend3d.com/t/cant-render-subd-surface/45672 "2007-02-18T08:06:30Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@user\_deleted](https://forum.highend3d.com/u/user_deleted)
#### Post date: [February 18, 2007, 8:06am UTC](https://forum.highend3d.com/t/cant-render-subd-surface/45672/1 "2007-02-18T08:06:30Z")
I converted a mesh to a subdivision surface after texturing the faces in polygon mode
and when i went to render i got this error: // Error: (Mayatomr.Geometry) : polyToSubdShape1, no material assigned to faces in subdivision surface base mesh, ignored //
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### Author:  [@dezz](https://forum.highend3d.com/u/dezz)
#### Post date: [February 27, 2007, 12:17pm UTC](https://forum.highend3d.com/t/cant-render-subd-surface/45672/2 "2007-02-27T12:17:21Z")
mental ray cannot render subD surfaces correctly
convert to poly
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### Author:  [@joojaa](https://forum.highend3d.com/u/joojaa)
#### Post date: [February 27, 2007, 2:27pm UTC](https://forum.highend3d.com/t/cant-render-subd-surface/45672/3 "2007-02-27T14:27:01Z")
Actually it can
However the term subd surface is starting to become a bit overloaded, as it is now maya supports no less than 6 different sub div schemes. And MR of 8.5 only supports 3.
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### Author:  [@dezz](https://forum.highend3d.com/u/dezz)
#### Post date: [February 27, 2007, 2:41pm UTC](https://forum.highend3d.com/t/cant-render-subd-surface/45672/4 "2007-02-27T14:41:54Z")
And thats the main reason MR is having shading and geometry issues when rending subD
I would be great if I could render subD with no problems
New and faster hardware is comming, hope mental ray makes good use of it and allows better subD support 
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### Author:  [@joojaa](https://forum.highend3d.com/u/joojaa)
#### Post date: [February 27, 2007, 3:34pm UTC](https://forum.highend3d.com/t/cant-render-subd-surface/45672/5 "2007-02-27T15:34:41Z")
Nothing to do with speed! Pixar has had this sloved for years now.
QUOTE(dezz @ 02/27/07, 04:41 PM) [snapback]261111[/snapback]
And thats the main reason MR is having shading and geometry issues when rending subD
Well no, its a limitation of language.
if I were to call the subd schemes arount the world:
Apples
Ornanges
Bananas
Grapes
and so on...
Now nobody in their sane mind would try to push A banana trough the holes reserved for grapes, but unfortunately they are called:
Subdivision Surfaces
Subdivision Surfaces
Subdivision Surfaces
Subdivision Surfaces
Subdivision Surfaces
The rederers of the world arent alone here to the onslaught of the confusion, in fact the SUBD scheme most of you call subdivison surfaces are called hierarchial subdivision surfaces. MR has no support for this (maya 8.5 had some upgrades tough), the reason is alias along with pixar hold this technology alone. Now thsi can easily be made compatible with MR all you need to do is collapse the hierarchy untill all faces are quad and theres no additional hiearchy with edits left. (theres no need to convert them to polys)
Hoover maya comes with a different sudivison scheme, that MR does support
And them maya comes with a support of scheme that PRman supports and so on...
Now how am i supposed to know what subd schemeyour talking. I assume first because you dont classify the others as subdivs but when you use a render you nee dto know the sceme in use.
PS if the language would be sorted then the problems would sort themselves out too.
PPS for stills the sane thing is to convert them to nurbs instead! As it renders much faster.
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### Author:  [@user\_deleted](https://forum.highend3d.com/u/user_deleted)
#### Post date: [February 27, 2007, 10:10pm UTC](https://forum.highend3d.com/t/cant-render-subd-surface/45672/6 "2007-02-27T22:10:36Z")
Hi! When you convert polys to subdivs you have to take care of a few things: first of all DO NOT HAVE the center of a face outside it's edges(if you are wondering how is that possible imagine two V one smaller and inside the other...if you take a look around maya docs you will notice what i want to say), do not have nonmanifold geometry faces with more than four edges (when converting most of the times you will get an warning)....instead of nonmanifold i have noticed that a triangle is better .Now have you notice that sometimes when you are working with subdivs proxy and you cut your original mesh some of the face on the proxy will disapear?Well, i don't have a clue whats happening , but deleting the history and then remaking the proxy will solve the problem.So delete the history on original and then recovert to subdivs.But take great care with that center of the face outside the edges! Most of the errors i get were this kind! Like a last resort triangulate all mesh... ) (just kidding).Hope i helped!