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MEL Commands to Control the V-Ray Framebuffer

If you need to script the V-Ray Framebuffer, there are a series of options that are shown when you enter “vray vfbControl;” in the MEL command line.

While there is no way to query current settings, you can turn them off with something like:

vray vfbControl -exposure 0;
vray vfbControl -curve 0;

It’s good to turn off the exposure and curves setting when doing stuff like wireframe batch renders that can be messed up by contrast and exposure controls.

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V-Ray for Maya Log Location

I just recently noticed that render output from V-Ray for Maya doesn’t go straight to the Console so I had to ask Chaos Group where the render log is on OS X. Both OS X and Linux’s are called vray4maya_log.txt and they are stored in /tmp. Open it in Console.app under OS X or tail in Linux and it will refresh automatically as messages are added:

The log location on Windows is in C:\Users\you\Appdata\Local\Temp.

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Maya’s “Duplicate Shading Network”: Not Just for Materials

Sometimes in Maya, you duplicate certain things like V-Ray lights with attached HDR images and only the light itself is duplicated, forcing you to reattach the image connections. In scenarios like this, you should use the Duplicate Shading Network command in the Hypershade:

That will duplicate the light and duplicate connections, so that get the linked sub-nodes. Those sub-nodes are also duplicates, so you can change the colour of an image connection without affecting the colour of the original network’s nodes. Since I use this often, I have this command bound to a hotkey in the Hotkey Editor:

hyperShadePanelMenuCommand("hyperShadePanel1", "duplicateShadingNetwork")

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Making V-Ray Renderable Curves from ZBrush Fibermesh Output

I’ve been playing with a lot of different hair workflows lately and found that ZBrush’s Fibermesh is good for making shaped, long hair, where this can be difficult to do with plug-ins like Shave and a Haircut or Yeti. Many people use hand-drawn guide curves with a Maya hair system and there is a good tutorial for that here. But I am using straight OBJ output from ZBrush’s Fibermesh and converting it to renderable curves with this Python script for Maya. The reason you want to do this is because faceted polygons will face in one direction and give you an unrealistic reflection while a renderable curve will more accurately imitate a round hair. So, here is a quick rundown of how you get your polygonal Fibermesh into Maya for use with V-Ray:

The nice thing about that script is that it lets you pick a threshold, so if you use a ton of hairs in ZBrush, you can set the conversion threshold to 0.5 so you only make half the curves. If you have too few curves even at 1.0, try using the linked workflow above to use the hair system approach to fill in spaces between the guide curves instead. You’ll want to use a much lower threshold for that though, since it is really slow to generate with a lot of curves. I had to do just that workflow in my example above. Here is the 1:1 fibermesh conversion:


It’s too sparse (and my hair is too thick).

and a 0.1 ratio curve conversion from the Fibermesh with a hair system applied and 28 hairs per clump assigned in the hairSystemShape1 settings:

the result:

Still needs work, but obviously it’s a lot closer already. Thanks to Roman Lapaev for the script link.

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Making a Shaped Water Ripple in ZBrush and Photoshop

So I’m working on this piece with a guy floating in the water and thought I’d share the workflow I used to make the simple water ripple around his body. Within ZBrush, have your water plane and object meeting and then take a screenshot from above with perspective off. Open the screenshot in Photoshop, crop it to square – since you’ll be making an alpha map for your brush – and then use outline as a selection. Offset the selection, stroke it and blur, and you now have an alpha map for ZBrush:

My water cube is too small but it’s just for a still, so I can clone out that wonky bit at the top. Also, water has an index of refraction of 1.333 but I used 1.6 to increase the refractive effect since I’m not going for realism. As you can see in the video, I like to use Smart Objects for my Photoshop layers since the blur filter can always be changed later if I want less or more of the filter and I can scale the stroked layers non-destructively.

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V-Ray Tuner 3.4.2 – Another Small Update

Just did a few fixes and small additions to V-Ray Tuner. Changelog lady:

Tumblr is all bunged up so read the changelog on the Creative Crash page.

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Using V-Ray Material Hair Materials with Shave and a Haircut

There is a dearth of workflow information around about using V-Ray with Shave and a Haircut (or Yeti), so I had to contact Vlado at Chaos Group about how to use the V-Ray Material Hair 3 material with Shave and a Haircut. In typical Chaos Group amazing support fashion, I got an answer when he woke up the next day. To apply a V-Ray material, you need to apply it to the “shavedisplay” node – select it in the Outliner…:

and then, in a viewport, right click and select Assign New Material and pick V-Ray Material Hair 3. Then you can change the hair colour settings but it won’t render in place of the default Shave material until you disable “Override Geom Shader” in the material section of the shape node for the selected fur:

Then you’re good to go:

I’ll be updating V-Ray Tuner’s linearize colour script to work with V-Ray Material Hair shortly. Keep you posted.

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Skip a Trip to Photoshop: Use the V-Ray Color Correction Node

V-Ray for Maya has some pretty handy (but slightly hidden) tools that can be added from the Create From V-Ray Plug-in menu and one of the best is the Color Correction node. It’s basically a grading dialog for textures and can do quite a bit, and it can save you trips to Photoshop to just do slight tweaks to hue, contrast, etc.:

The only thing to keep in mind is that the brightness is a gain slider, not a gamma-based correction, so it should be avoided to adjust mid-tones. Also, you can try out the other Color Correct plug-in for yourself but it’s less full-featured than the Color Correction plug-in. Why they are so similarly named is a question for the sages.

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Small Maintenance Update to V-Ray Tuner for Maya 2014

V-Ray Tuner 3.4.1 posted for download. There’s not too much new here but there’s an important fix for the Optimize button script for Maya 2014. Maya 2014 has a bug that returns the wrong number for RAM amount for “memory -phy” so, if you’re running 2014, the script asks you to enter your memory amount in GB. Otherwise, the only other new addition is that I’ve added Point Light support to per-light render script.

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V-Ray Tuner 3.4 Update Releasededed

This is not a huge update to V-Ray Tuner but it brings a few fixes and features that affect various things. Here’s 3.4 changelog:

  • Composite pre-bake diffuse colour with V-Ray Dirt RE:
  • Changed DaveBake420 10% value to be 512x512, instead of 409.6x409.6 (10% of 4096).
  • Attach Cam button now prompts you to add and enable physical cam attributes if you don’t have them already on the selected camera. If you select no, it will still hook up the overscan setting.
  • materialDropper and materialCopyDropper now work on face-level selections as well as with objects.
  • Optimize button now sets memory setting (sys_rayc_dynMemLimit) to 80% of total memory in your system.
  • Fixed material worker layer script. I had started to implement a new feature but forgot to finish it so it was broken for a couple versions.
  • Per-light render script now does solo light re-renders. If you have a light selected and run per-light render, it will only render that selected light:
  • Small fix to per light exposure light tweak - it could fail to properly detect your light selection before.
  • Revert To Saved Document script added to Utils menu.

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