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Texuring Techiniques > Material Tips and Tricks Part 3 (Posted By: 3dmonster)
:: Post Date: 2007-09-17 20:18:55 [Post Comment] [Post Articles]

Material Tips and Tricks Part 3

Application Used: Autodesk VIZAuthor: Montree T.

Contact:easyyong@hotmail.com

Material Tips and Tricks Part 3 – Continued

3. Tips for reflection and refraction maps

3.1 Perpendicular and parallel

The anisotropic effect produces different kinds of reflections. The reflection will change more or less depending on the viewing angle. The least reflection will appear on a suface that is perpendicular to the camera and the most reflection will appear on surfaces that are parallel to the camera. This effect is called the fresnal effect.

1.You can see this effect on most of the anisotropic objects ie. damp/wet road, water surface on swimming pool, polished leather, some kind of metals and etc.

The reflection is changed in every angle. The bird's eye angle has less reflection and more reflection at the worm eye view (where the camera angle is almost parallel to the wet floor)

2. Curve/freeform object ie. Cylinder, and sphere and etc.

The least reflection is at the middle of the cylinder where the surface is the area perpendicular to the camera and the more reflection is on the suface which is parallel to the camera.

You can create this effect by using a falloff map (perpendicular/parallel or fresnal) over raytrace. Both perpendicular/parallel and fresnal produce almost similar effects, but I found perpendicular/parallel to be more apparent.

3.2 Shadow and Light

Falloff "shadow and light" seems far different from the real world reflection. I am not sure if there are any theories about this, but I just use it to accelerate the reflection at the light area and dim down the reflection in the shaodw areas. This will create a "subdued mood" in your scene. Imagine the reflection on a black granite floor in a pub. The bright area will blow the light and will then disappear into the shadows.

Here are the parameters and settings of Shadow and light.

A rendering with Shadow and light falling off. The reflection gives a subdued mood.

3.3. Some examples of complex scene refractions

This is quite off-topic in that it doesn't lend itself to our architecural tutorials, but we basically need to know how it works so that we can apply it on our own .

3.3.1 Create water drops on a glass

I will skip mentioning about details on lighting as this is a simple scene. Let's just look at the wire frame only.
After a few time tests on the materials, I decided to use raytrace material as the effect is much easier to create than standard material. Also, I found the splash map is the more suitable than cellular as the effect appears clearer. I used blend material for the glass model which contains 2 materials ie. glass material and water material and a splash map for masking.

The rendering time was about 32 minutes and it was quite long for a dual processor.

Glass material legend.

1. Glass material. It seemed to be very easy as I didn't even put any map on it. Just changed the color of diffuse, transparency and reflection and change the IOR to 1.5.

2. Water drop material. I just copied the same mateial from the first slot and changed the IOR to 1.333 for the water, and copied the same masking map (slash map from slot#3) and placed it on spec.level and Bump.

3. Masking map : splash

This is the floor material which uses a similar technique to the blend material.

The image above is very close to the 1st one, but uses only material#2 which is the water. There are bump and specualar effects except that it has only 1 IOR that is set to 1.33. If you don't mind about the IOR. The rendering time is quite fast at 3.32 minutes.

3.2 Diamond

Someone had asked me how to draw a diamond. Rendering a diamond is not as difficult as you might think. Just use raytrace material and change the transparency to white, IOR=2.417 and facet, that's all. The diamond model and its surface is also important that you need to find a blue print to see how it looks before you draw it.

This is roughly how the edge of how the diamond looks like.

Put several colors of lights around the diamond.

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