Thursday, November 26, 2009



FOG LIGHT/GOD RAYS IN MENTAL RAY

Of course, it's not easy as with most things in MR but here it is.

1. Create a poly object (cube) which will act as a 'container for your fog.
The smaller the container the less calculations Maya has to make.
2. Create a light that will be your fog light. Turn on raytrace shadows with trace depth 5.
(use MR lights for cooler results, i.e. attach a physical light to a spotlight)
3. Make sure your objects are within your container.
4. Create a shader (lambert) that you will apply to your container.
5. Open the lamberts 2sg node and hook a transmat node to it's MR custom shaders
-material shader and shadow shader. This will make the container's geometry
invisible to the renderer.
6.Connect a parti_volume node to the volume shader slot.
7. Turn up the parti_volume's scatter a bit.
8. In the parti_volumes attributes, link your light to it through the light linking
drop down.
9. In your render globals, Features...turn on auto volume volume samples 8.
10. Under quality, Raytracing...turn shadows up to 6.

There it is, your 10 steps for a simple effect. Now tweak your parti_volume
node to death and have fun ! (Min Step Len lower makes fog less grainy)
Those render times are gonna be pretty harsh!

Friday, November 06, 2009



EDIT EDIT EDIT ** ALTERNATE VECTOR BLUR METHOD

Sure enough bloody Mental Ray lack of integration has done it again...and
MAYA HAS IT'S OWN LM2DV SHADER ---- HELLO 64 BIT VECTOR RENDERING
Well the geniuses at Autodesk have hidden some very good shaders called MIP. shaders
the one we want is called mip_motion_vector.
http://www.pixelcg.com/blog/?p=528

To enable them in the mental ray shaders GUI under materials and output shaders
go into your mentalrayCustomNodeClass.mel file in (in ../scripts/others)
http://forums.cgsociety.org/showthread.php?f=87&t=541718&page=1&pp=15

Edit: It came to my attention there is an easier way of exposing these shaders
in your script editor type
optionVar – iv “MIP_SHD_EXPOSE” 1;
restart Maya and the shaders will appear !

VOILA
your own shader group that you paid Autodesk for but they didn't want you to have it.
NOW
In the mip_ node Connect the message to mental ray miOutputShader node of whichever camera you are using via the connection editor-
you have a perfectly working LM2DV shader. Don't forget to enable vector and depth in the Legacy Output Shaders in your camera's attribute editor. Also enable motion blur with
equal shutter values as you would for the LM2DV shader.

NEW RSMB MBLUR VECTOR TECHNIQUE

Well, seems that the LM2DV shader for rendering out motion vectors is kaput. The guy who developed it has changed his website...BUT

Innovation has arrived. Seems you can render out a 2d vector pass with Mental Ray's output passes that are actually better. Here's the tutorial.


http://aloedesign.com/2008/12/maya-2d-motion-vectors-tutorial/3/
Font size

Thursday, November 05, 2009

MUDBOX TIPPAGE

Always have trouble extracting displacement maps from Mudbox.

* Always model quads. Mudbox calculations hate ngons & Tris.
* Check for non-manifold faces. Destroy them.
* Make sure UVs are clean and that shells have some distance from eachother.
* Use as few UV shells as possible. Map extraction is slow with many shells.

Wednesday, November 04, 2009

WIREFRAMING A SUBD OBJECT

This one is a bit of a hack because it's hard to render a subD wire object with backface culling.
Contour shader only wires polys and the the hardware buffer sux at culling.
Basically we create the wires by saving a playbast.

1. Apply a black shader to your object.
2. Turn on 'wireframe on shaded under shading.
3. Turn on 'smooth lines
4. Adjust 'thicker lines
5. Playblast out your animation and save it to whatever resolution you need.



MAYA WIREFRAME RENDERING VIA MR CONTOURS

Here's a cool wirefframe render technique.

1. Apply a shading map shader to an object.
2. In the SG material node, check enable contour rendering under the mental ray tab.
3. Enable contour rendering under the Render Settings/Features/Contours.
4. Crank over sample.
5. check "Around All Poly Faces" under Draw By Property Difference
http://img261.imageshack.us/img261/9059/contour.jpg
OR
http://ashutoshjha.org/tutorial/wireframe-render-in-maya.html