Saturday, 9 April 2011

Maya Tasks Week 24 - Dynamics and Mental Ray

In this weeks dynamic tutorials we continued with particles.

The first example is of mud sliding off a golf ball. The particle render type was set to blobby surface to make the particles a solid mesh that would deform over the ball. Various scripts were used to control the way the mud slid off the ball.

The second example uses particle sprites to create magical dust. A sprite is an image and in this case its an image of a bright star like glow.
Scripts control the look of the particles, from colour to size and rotation etc.
Then it was taken into after effects for further adjustments.

Mental Ray


in this rather short tutorial we tapped into some caustics. Caustics are what cast bright hot spots when light refracts through materials such as glass or water.
This example shows how caustics has an effect in this scene.

No caustics

Caustics added

Notice the bright white glows mixed in with the shadow.

Mia Material X

The Mia Material X shader for Mental Ray is a very versatile shader. It can be made into almost any type of material. In this exercise we looked at all the preset materials. You can see that they can be made to look very realistic.



HDR Image Lighting

In this exercise we looked into Image based lighting with HDR images.

-colour gain
-colour offset

With no image based lighting

Default image based lighting settings - 0,1
Looks like night time

With an offset on colour gain and colour offset by 1 - 1,2
A reasonably good looking render

With an offset on the colour gain and colour offset by another 1 - 2,3
Slightly blown out.

I found that keeping the settings within a range of 1 kept the colours neutral.
When just increasing the colour gain alone the image tinted blue! - 0,5

Tweaked settings - 1.3,2.3

Physical Sun and Sky with Portal lights

A default sun and sky set-up works great for outdoors, but not so with interiors, as seen in this render.

Not enough light seems to enter through the window of the room, so to fix this we use portal lights. A portal light focuses the light into entering the room.

This is how a portal light positioned just outside the window, helps improve the image.

I then experimented with some ambient occlusion.

Also in the occlusion settings is a colour bleed option.
Here is the final result.

The Physical Sun and sky

This exercise went through some of the more advanced features of the Physical sun and sky in Mental Ray.

Here we have an island scene with the default sun and sky.

First that was tweaked was the horizon line.

Then the sun position was changed by rotating the directional light that represents the sun.

The sun disc size can be changed to. In this case I made it slightly bigger.

Now the sun is changed back to early mid day, I shall go over a few of the other settings.

The haze attribute affects how much atmosphere is in the scene.
from left to right you can see how less haze is clear and adding more haze gives us something more overcast.

The Red / Blue Shift can be used to similar effect.
a range of -1 to 1 can be used in this channel.

The last key attribute is the Saturation.

Most of the effect changes can be seen in the sky and in the reflections of the sky.

Shadows can be tweaked also. This is the default.

After increasing the softness grain starts to notice more.

So increasing the samples helps remove it.

Last but not least, I have finally gotten round to finishing the weight lifting animation! I am quite pleased with how its come out, considering only a day was spent on it. Usually for something like this I would spend at least two days.
The video starts with the keys in stepped mode and then the final animation.

I think if I had that extra day I could have spent more time in the curves editor, fixing all of the overshot curves etc. Most of what you see was done without going into curves editor at all except for fixing a rotational glitch in the wrists.

I think that should be all the Maya tasks done for this project.

A Flock of Pixels

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