Maya Station

mib_amb_occlusion texture on Mac OSX

Just a quick heads-up about the mib_amb_occlusion texture. Render the texture from the Maya 2011 Terminal on the Mac and you will get an unexpected result...In this example, I've connected the output of the mib_amb_occlusion texture to the Color attribute of a Maya Surface Shader (AO is disabled in the Render Settings).

This is because the value of the texture's Spread attribute is not getting correctly exported. By default the attribute is set to 0.8, but rendering from the Maya 2011 Terminal sets the value to 0.0.

You can workaround this by keying the mib_amb_occlusion Spread attribute, to force the required value to export.

Owen

Autodesk Maya 2011 Hotfix 2

Autodesk releases its second Hotfix for Maya 2011. Download it from the Autodesk website.

Please refer to the readme file for the complete list of issues addressed in this Hotfix.

Note: You will also need to update your installation of mental ray Satellite and Standalone to benefit from some of the fixes in this release. Remember to uninstall your current installation of Maya 2011 before installing Maya 2011 Hotfix 2

For a complete rundown of what's new in Maya 2011, please refer to this post.

Object distance from camera command.

If you would like to use the HUD and enable Object information.
You would get the object distance from the camera.

In order to get the MEL command that does that, one should first consider that the Documentations states
“This setting is used to select certain pre-defined HUDs, some of which retrieve specific data, that is unobtainable through normal MEL commands or scripts.”

The workaround  would be doing something like so

vector $p1=`getAttr persp.translate`;
vector $p2=`getAttr pSphere2.translate`;
vector $result=$p1-$p2;
print (mag($result))

Thanks to Lap Ho for his tip.

Maya, mental ray standalone and iray

Outlined here is a (simplified) approach to using iray with Maya - if you have mental ray standalone 2011 licenses:

1. In Maya use 'export all' to create a .mi file,
2. Render the file from the command line: ray -iray on [further options] <filename>

For more details, including setting string options to turn on iray, see this post on the mental images forum: http://forum.mentalimages.com/showthread.php?t=6584

A couple of things to look out for:

• if your images turn out black: "Maya light sources with high intensity values", depending on the scene size that may mean very high intensity values (like 1000000 or more),
• if the quality is too low you may need to increase 'progressive max time' either in the scene/.mi file or by using the -progressive_max_time xxx option on the command line,
• if you need more samples increase 'progressive max samples' or use the -progressive_max_samples xxx option to override the value set in the file.

To compare the speed on the graphics card vs the speed on the cpu you can use the -iray option: -iray on uses the graphics card, -iray cpu uses the cpu.

If you set verbosity to 4 (add -v 4 on the command line) you can check which CUDA devices are being used:

• With -iray on you'll see something like:
  
  IRAY 0.2  info : found 1 CUDA devices
  IRAY 0.2  info : defaulting to use all CUDA devices
  
  
• With -iray cpu you'll see something like:
  
  IRAY 0.2  info : found 1 CUDA devices
  IRAY 0.2  info : empty device string, using CPU backend exclusively
  
  In case you don't have any CUDA capable devices in the system you'll see:
  
  IRAY 0.2  warn : no CUDA capable devices found
  IRAY 0.2  info : using CPU backend with 2 threads 

Thanks to Nicolas Holst for this post.

Maya 2011 on Xeon systems

If you are using Maya 2011 on Xeon system and are faced with speed issues, you might want to disable the Parallel memory variable by doing the following.

Set this environment variable MAYA_NO_PARALLEL_MEMCPY to 1
This will disable the parallel memory copy.
In some cases, parallel memory copy is faster on Opteron and Nehalem based systems.
Note Another factor that may impact speed is the workload running in Maya.

Error: Cannot change topology

Users would get this error in some of their models when they trying to create their UV maps.
// Error: Cannot change topology, poly mesh has allowTopologyModification attribute set to false //

The solution, is to make sure that the Allow Topology Mod is turned on under the shape node of your mesh.

Why does the render command create folders for my images?

If you use the command render to create images from a given camera, you may wonder why Maya  sometimes creates an extra folder, labeled with the camera name, and saves your image here rather than directly in the Project/tmp directory.

Let me explain when this happens, and how to avoid it.

Elliptic filtering is causing artifacts in reflection when rendering with mental ray

If you would to use elliptic filter on a file texture that is reflecting on a surface, you would see this type of artifacts in render.

 

At this point this matter was reported as a BUG, the developers are currently looking into this issue.

RGBE framebuffer

RGBE is one of the framebuffer that is over looked by users. It actually allows the pixels to have the extended precision of floating point values.

If you would render it an .EXR file using RGBE 8bit, and open it in Toxik it will indicate it’s a 16 bit.

 

Note: other application might read it as 32 bit.

However it has considerably less precision than a true 32 and 16 bit exr. 
Please note it is not a real substitute for 32 bit, but it will give you way better result that a regular 8 bit.
So give the RGBE a chance in your next render.
:)

Blurry reflection with mental ray 2011

If you would render a reflected file texture in Maya, you would notice that the further away the object is , the more blury it gets.

This matter has been reported as a BUG, and currently under the developers investigation.
However, If you wish to cancel this blur. You would need to turn off the file node filter.

You can also use the filter slider found under Effects.

Another woraround is to use mia_material and disable "Export shading engine"