View Full Version : Vray Rendertime Subdivision

07 July 2010, 09:01 PM
Hi everybody,

I have a small question about "Vray's Render as Subdivion surface" option

Inoticed that it infinitely smooths the mesh, but cranks up the render time significantly, and sometimes causes the render to crash
I really wish if there is an option similar to mental ray's subdivison approximation, in which i could control the amount of subdivisons at render time.

otherwise, i would have to smooth the geometry and deal with tons of polygons in the viewport.

any ideas or suggestions.

07 July 2010, 12:26 PM
Render Settings>VRay>Global Options: Turn on "Render viewport subdivision". should work pretty much how Mental Ray handles viewport subdivision(i.e. hitting 3 on the keyboard)

07 July 2010, 12:36 PM
nm, you're talking about the same thing, and I see the issue you're talking about. Have you posted this on chaosgroup's maya forum? They're usually pretty responsive, and it's a valid issue

07 July 2010, 07:29 AM
I had the same problem....simple solution is

turn on "render viewport subdivisions" and change subdivision settings in vray "settings" tab from default lenght "4" to something like 15 or 20 (approximately subdivides like the viewport)

whenever you need better subdivision just select that object, go to attributes tab and on the top menu look for "attributes" and vray attributes and assign node "subdivision and displace quality" which basically overrides the global subdivision settings so you can tesselate it more (lenght like 4 or so)

Hope this helps.


07 July 2010, 07:51 PM
Thanks for your response, i think Libor has got the solution

Really you've got the solution.
even 60 subdivides like the viewpoint,.
Thanks a lot.

07 July 2010, 01:59 AM
As Libor pointed out, you can also set this on a per object basis by adding some extra vray attributes from the objects attributes menu in the attribute editor. I've written a little script that allows me to do this easily for multiple objects.

I found it useful, in either case, to leave the edge length at 4 in screen space and to limit the subdivs to something like 16 for most of my objects. This means it will attempt to subdivide until it gets an edge length of 4 pixels, but will never subdivide more than 16 times.


07 July 2010, 04:09 AM
great tips!

I'm happy to see you are using VRay, 'cause that means the useful scripts for it will start to show up on your blog :)

07 July 2010, 08:46 PM
vray4Maya threads are starting to fill up :D .
djx , can you share the scripts for applying the subdivision on multiple objects :bounce:.

I tried myself but was having problems with the vray attr on multiple shapes . Working on single selection though . Thanks :)

07 July 2010, 12:58 AM
My script is very basic and just loops though a selection of objects and adds the attributes and sets them to my preferred values. You can just select the top of the heirarchy and it will find all the shapes below it. The trick was to use "evalDeferred" to set the attribute values to ensure the attributes new get added first. I plan to write a little UI to make this a bit more user friendly (or maybe chaos will integrate vray attributes into the spreadsheet).


07 July 2010, 02:46 AM
DJX, I think I owe you about a hundred beers now if we ever cross paths.

I've worked on several versions of similar scripts and it's always been a run the command twice thing because the attrs don't exist fast enough. Didn't even think to look into evalDeferred.



07 July 2010, 08:51 AM
Wow ! thanks alot David :bowdown:

07 July 2010, 08:02 PM
David, i think your script is very useful

Thanks all this was a very useful thread for me

07 July 2010, 07:29 AM
In my previous post I wished for vray attributes in the attribute spread sheet.

Well I just discovered that they are already there, but if they are on the shapeNode (like they are if you use my script) then you need to select the shapeNode to see them. You can do that by selecting in the viewport and using the down-arrow to step down onto the shapeNode, or you can use the outliner with shapes display on.


CGTalk Moderation
07 July 2010, 07:29 AM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.