In this tutorial we are going to look at one of the indirect illumination models available in mental ray.
Final Gather
What is indirect illumination? For that matter what is direct illumination?
In 3D computer graphics, direct illumination is any illumination an object recieves directly from a light source. If you have a spot light aimed at your object and it is illuminating it. That object is recieving direct illumination from that light source. (see image below)
Indirect illumination is illumination an object recieves indirectly. In real life, a light photon doesn’t simply come from a source and hit an object and stop. It bounces off of that object and travels around a given space until it’s energy runs out. Think of an overcast day. The clouds completely block the suns "direct" illumination from hitting the ground, but we can still see there is light outside. However, the light is dimmer, more even and shadows are extremely soft. (see photos below)
Direct Illumination
Example
Indirect Illumination Example
So, how do we do this in computer graphics? More specifically in Maya? More specifically with Mental Ray?
I am glad you asked.
As stated above one of the tools we have for achieving this is called "Final Gather."
Lets get started shall we!
First we need to Acquire a model to work on.
- 1. Go to file>Open Scene and choose the cornellBox1.ma file (This will be in the mentalRay project provided in the first mental ray tutorial)
- 2. Once the file is opened you should see something like the image below.
This scene is what is called a cornell box. You may have seen examples like this online. It is a standard way to show how light works.
We are looking into a cube with a hole in the top. The back wall, floor and objects all have a white lambert applied. The left wall has a green lambert applied. The right as a red lambert and the ceiling has a blue lambert. The reason for the colors is to both see how the light effects different colors and to see how the colors will bounce around the room with final gather.
Our direct illumination sources are a spot light aiming through the hole in the ceiling. It is casting soft raytracing shadows. We also have a fairly dim point light outside of the front of the box to add a bit of fill to the scene to brighten up the shadowed areas.
Rigging in computer graphics (aka. puppet setup or animation setup) is the process by which complex animation units are given simpler higher level controls in order to make the process of animating faster, better and easier. The goal for a setup artist is to provide a rig to the animator that allows them to spend more time refining the shot the way they want it rather than fiddling with a faulty rig that limits what they can do. There are a zillion methods to solve an array of problems but there are some basic bulidng blocks we must establish before one can delve into the process of rigging.
This video is 1 of a set of 5 videos that will introduce the most basic tools and concepts available in Maya to start you off on a good grounding for creating some amazing and effective rigs.
lets get started shall we!
4. Expressions
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Rigging in computer graphics (aka. puppet setup or animation setup) is the process by which complex animation units are given simpler higher level controls in order to make the process of animating faster, better and easier. The goal for a setup artist is to provide a rig to the animator that allows them to spend more time refining the shot the way they want it rather than fiddling with a faulty rig that limits what they can do. There are a zillion methods to solve an array of problems but there are some basic bulidng blocks we must establish before one can delve into the process of rigging.
This video is 1 of a set of 5 videos that will introduce the most basic tools and concepts available in Maya to start you off on a good grounding for creating some amazing and effective rigs.
lets get started shall we!
3. Constraints
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Rigging in computer graphics (aka. puppet setup or animation setup) is the process by which complex animation units are given simpler higher level controls in order to make the process of animating faster, better and easier. The goal for a setup artist is to provide a rig to the animator that allows them to spend more time refining the shot the way they want it rather than fiddling with a faulty rig that limits what they can do. There are a zillion methods to solve an array of problems but there are some basic bulidng blocks we must establish before one can delve into the process of rigging.
This video is 1 of a set of 5 videos that will introduce the most basic tools and concepts available in Maya to start you off on a good grounding for creating some amazing and effective rigs.
lets get started shall we!
2. Direct Connection
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If you find yourself modeling something that is symmetrical and want to be able to model on one side and have the other side update automatically, then here are a few steps to get you going.
- Make sure you have an edge loop running down the center of your model. Specifically the axis upon which you want to mirror.
- Go into component mode (faces), select half of your models faces and delete them.
- Go back into object mode and make sure your half model is still selected.
- Check that your objects pivot point is sitting on the axis you want to mirror. If not, put it there (insert on pc, home on mac).
- Go to Edit > Duplicate Special []
- Make sure you have instance selected instead of copy.
- Set the scale value of the axis you want to mirror to -1.
- Hit Apply.
Now you will have your model in complete form again. However, if you start tweaking vertices on one side you will find the other side does exactly the same thing only mirrored. Caveats: Since you are ‘essentially’ working with 2 different objects at the same time you will always have a seam running down the center. Even if you work in smooth preview mode you will see the seam. Don’t worry about that while modeling. Just remember that when you are done, simply delete the instance and do a proper mirror and merge. The seam vertices and your model will be as smooth as you need it to be. Often you might find that there is a gap in the seam. If so, you can move all seam vertices together to close it, or make sure your pivot point lines up with the seam before doing your instance mirror.
Rigging in computer graphics (aka. puppet setup or animation setup) is the process by which complex animation units are given simpler higher level controls in order to make the process of animating faster, better and easier. The goal for a setup artist is to provide a rig to the animator that allows them to spend more time refining the shot the way they want it rather than fiddling with a faulty rig that limits what they can do. There are a zillion methods to solve an array of problems but there are some basic bulidng blocks we must establish before one can delve into the process of rigging.
This video is 1 of a set of 5 videos that will introduce the most basic tools and concepts available in Maya to start you off on a good grounding for creating some amazing and effective rigs.
lets get started shall we!
1. Proper Scene Organization
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