frame by frame command line rendering

david | mentalray,rendering,tutorials | Wednesday, February 17th, 2010

If you don't have access to a render manager, or even if you do, you might want to render from the command line one frame at a time. There are a few reasons why you may want to do this. Sometimes maya does not get to the end of a long batch render due to memory errors. You set off a 100 batch and it dies after frame 27 maybe. Another reason is that sometimes your animation does not seem to work in a batch render. A single frame renders correctly, but when you batch it some things don't update correctly. (more...)

poseDeformer walk-through

david | animation,mel script,tutorials | Friday, October 2nd, 2009

I was asked to write a simple getting started guide for using Michael Comet's poseDeformer, so here it is. (more...)

p_HairTK, p_HairTK_shadow, p_shader_replacer

david | mentalray,rendering,tutorials | Tuesday, April 14th, 2009

These 3 custom mentalray shaders are part of an extensive shader collection written by Pavel Ledin (aka puppet). In this post I will show how you can use a geometry shader, p_shader_replacer, to assign the p_HairTK shader to maya fur when using mentalray with fur mode set to hair primitives. Doing this gives you much more control over the look of the fur and, depending on how you use it, may dramatically improve yoru render times.

(more...)

p_color_plus_alpha

david | mentalray,rendering,tutorials | Monday, March 30th, 2009

Most of the time its ok to mix maya base shaders with mentalray shaders in the same shader network but sometimes things don't work as you would hope. An example of this is when you layer something like a blinn and a mia_material_x using mib_color_mix. At first glance the render looks correct, but you will find the blinn is missing in the alpha channel. A quick fix is p_color_plus_alpha.

(more...)

single axis aim constraints

david | tutorials | Tuesday, December 9th, 2008

You can use an aim constraint to make one object face another, but what if you also want that object to only pivot around a single axis. An example of when you might want this behavior is a candle flame made of a simple texture mapped plane. To create the illusion of a 3d flame you need it to face the camera, but you only want it to rotate around its y-axis so that the flame stays vertical even if the camera moves up higher than the candle.

To do this you could simply make an aim constraint and select only the y-axis to constrain, but you would discover that it doesnt work they way you might expect.

(more...)

mip_binaryproxy

david | mentalray,rendering,tutorials | Thursday, October 30th, 2008

I was looking through the "Whats New" section of the maya 2009 manual and read this about Render Proxies

Use render proxies with mental ray rendering to manage large scenes with complex geometry. Export your complex object as a mental ray assembly file, then replace it in your scene with a placeholder object that references this file. When you render, the exported object is loaded into memory and rendered with the rest of your scene. Translation time and memory usage are cut down, allowing mental ray for Maya to render large scenes.

And that prompted me to write about the mip_binaryproxy node. Those of us who are sticking with maya 2008 for the time being can use mip_binaryproxy to implement render proxies almost as easily as our friends with maya 2009. (more...)

linear workflow and gamma update

david | mentalray,rendering,tutorials | Monday, October 6th, 2008

Last month I wrote about how I implement a linear workflow in my work. Since then I have noticed that in at least one area I'm doing it differently to many others - and now I know why they are right and I was wrong.

It boils down to this: I've been leaving my frameBuffer gamma at 1 (the maya default) and setting my output gamma to 2.2 via an exposure node, which means I need to degamma my 8 bit fileTextures (but 32 and 16 bit floats are ok). However the other (very popular) approach is to set the frameBuffer gamma to 0.455, and the output gamma to 1, which means generally the fileTexture requires no degamma.

When making my choice I weighed up both methods and I said to myself "The frameBuffer gamma defaults to 1 and the exposure node defaults to 2.2 gamma, so I'll stick with that. After all, it looks the same in the render..." BUT ITS NOT! (more...)

mib_continue and mip_rayswitch

david | mentalray,rendering,tutorials | Thursday, September 11th, 2008

I read a thread on cgTalk, which was started by Filip Orrby, in which he asked "How to make object not block FG rays?". He went on to answer his own question and since it is similar to a technique I use, I decided to elaborate.

I'm going to write about a shader and lighting setup I use a fair bit for product shots, where the background is very simple, often white and the product is to be brightly lit. For my final renders I usually break things into render layers, but I like to be able to quickly render everything in one pass to evaluate my animation and to show my progress to the client.

Here is a typical example of the end result.

mib_continue_YES.jpg

To see a step-by-step breakdown of the setup, click here (more...)

tips for rendering maya fur with mentalray

david | mentalray,rendering,tutorials | Sunday, June 29th, 2008

I've been working on a project involving the use of maya fur. It's the first time I have rendered fur using the mentalray renderer, so there was much to learn. One of the difficulties I encountered was dealing with the illumination of near-white colored fur (like a polar bear). In the past, using maya's native software renderer, I would have added fur shadowing attributes to my lights to allow me to control and balance the amount of illumination on the fur, but these attributes are not supported by mentalray so I had to find another way.

In this post I show an approach to rendering near-white colored maya fur with mentalray.

(more...)

djDepth phenomena

david | mentalray,rendering,tutorials | Tuesday, May 6th, 2008

Last year I wrote about my experiences creating a mentalray phenomenon called dj_mix_colors. Shortly after that I wrote about how to create a zDepthDOF shader using some of the standard maya utility nodes. Now I'm going to combine the two ideas and build a zDepthDOF style shader as a mentalray phenomena.

Let me start by saying all I'm really doing here is emulating (once again) the zDepthDOF shader by Andreas Bauer. But I have two reasons for doing so. Firstly I have recently become aware of a suite of freely available mentalray shaders called drUtilSuite 1.01 written by Duiker Research. It contains roughy 200 shaders

...to provide clearly defined atomic operations that may or may not be available already in Maya and mental ray.

Most accomplish a single basic task and they are designed to be built into something bigger. So I decided that it would be a good exercise in phenomenon building to create something useful. And that brings me to my second reason.

These shaders are provided for windows x32 and 64, linux x32 and 64 as well as osx uni, so they could fill some of the gaps currently facing those on modern os's.

You can download djDepth with some example scene files from here.

If you are interested in the full story click here to read (more...)

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