Fur Strategies and Techniques

Having the right tools and knowing how to use them, coupled with clear thinking and a bit of preplanning, go a long way in making any 3D project a satisfying success instead of a unhappy frustrating experience. Sasquatch's fur tools are powerful enough to handle any project from a simple tribble to a photoreal animal.

This chapter shares some of the clues and techniques discovered in-house There's no absolute rules about how to make fur, but we hope these tips give you some guidance as you learn. We hope you will teach us more as you discover new methods we never even considered!

Source Material

One of the first things you should do when beginning a fur project is gather plenty of reference material about your subject. There are many resources available online or in your local library. The children's section is by far the best source for clear, high resolution animal pictures. Analyze the subject to determine the different types of fur that grow from its body, noting where they are placed and how they are combed. It's a good idea to scan a photo and mark the different fur types in your favorite paint program or with a pen. Pre-planning helps a lot!

If you're attempting a complex photoreal project, it's best to prepare some starting images to make texture mapping easier later. Load your animal object in Layout or Modeler and create several orthographic images that can be used for planar mapping your painted images.

Preparation and Mapping

In your paint program (we use Photoshop), mark off the key areas on your model that you'll want to apply different attributes to. A wolf, for example, has short straight hair on his face and legs. Its tail can be droopy and bushy. The neck and upper body can contain tangled ruffled clumps. The inside of the ears have thin swirls of fur and the back of the legs sometimes have long and frizzy strands. It's best to save each of these special areas as a different Photoshop selection so that you can bring each area in for painting as needed. You can also use these selections as density maps to speed up the interactivity of your work, since Sasquatch can render more quickly when applied to a smaller area of the object. You can use LW's Limited Region in the same way.

In Layout, pose your object and keyframe several different camera views. As you progress through the project, you'll probably add more camera keyframes as you zoom in to work on different details. In the beginning stages there's not much need for fancy lighting setups. Just try to make sure the model is evenly light from all views. While in the combing and styling stages keep shadow options off since they increase render time and aren't useful in these situations.

Combing

A good place to begin with Sasquatch is combing. Make your fur very coarse, short, brightly colored, and very sparse. Turn off Tangle, Curl, Frizz, Kinking, and Clumping. The setup will give you quick and easy to see feedback as you tweak your combing pattern. It won't be photoreal, you don't want that yet, you want clarity and speed!

Sasquatch's "Smart" Surface Combing feature is especially useful at this point. For a animal, you might choose the nose as the Comb Definition Surface and set the strength to 50% or more. This will cause the fur to flow along the body, down the legs and out the tail in a natural pattern. For some meshes, this will be all the combing you'll need to do! A complex shape like a wolf, however, might need some further tweaking. One problem might occur at sharp features like ears where the flow of fur could bunch up at ear base, or on the rump and back of the legs where the separate rivers of fur from each side of the body converge. It's usually easiest to solve these problem areas by painting a surface combing strength map and making the problem area darker or black to reduce the smart combing strength. You can then bring the same map into the Comb Bias S~panel and invert it so that Bias Combing is now strongest where Smart Combing is weakest. Now you can use bias combs to rectify the problem areas.

The next stage should be styling. You can still keep density low for faster feedback, but other attributes should be tweaked toward their final settings. For complex objects like a wolf, it's probably best to paint on many settings since it offers much more control. Use gradients to smoothly blend different areas like the body and the legs together. For fastest interactivity, keep both LW and your paint program open at the same time so you can tweak an image and quickly replace the original in LW. Most of the time it's to best to map the area in 50% grey so that Sasquatch's S~panel Bias % will be equal to the grey value of the map, making it easier to tweak the setting in Sasquatch rather than in Photoshop.

Styling and Density

Some attributes have a direct effect on others. Increasing clump haircount will eat up the coverage so that it may be necessary to increase density to compensate. Very curly hair might need a boost in length for the required look since much of the length goes into the curl. Increasing length will also automatically increase coarseness. One trick is to invert your length map and use it as a coarseness map so the the fibers stay the same thickness as they get longer. Ruffles are often seen in animal fur. One way to create them is to use a fractal noise pattern in the combing S~panel with black set to negative values and white set to positive.

When you're happy with combing and styling, it's time to set the density, since the last steps, coloring and shading, depend so much upon it. Increased density has a direct effect on render times so use the smallest value that still gives good looking coverage. One trick is to color the underlying surface the same color as the fibers that grow from it. Make a quick render and using QV or a paint program, find the RGB values of your fur. Apply these same colors to your underlying object surface as a fractal pattern. This can really decrease the amount of hairs required to give the appearance of full coverage, especially if the object isn't close to the camera.

Color, Shading, and Previes

The last step is coloring and shading. We highly recommend doing this last for two reasons. One is that the color and shading can depend very much on density and styling. Color settings that look good on thin straight hair might look not work on a thick coarse and tangled wolf pelt. The second reason is that you can tweak all your color and shading settings in the Sasquatch preview without having to do multiple renders.

Before making a preview, it's crucial to lock down your final lighting setup. Once the lighting is set, zoom in closer to the object or area you wish to work on and create a preview. All the coloring and shading attributes except Direct Lighting can be interactively tweaked, providing a quick and easy method for achieving the final look you're after.

Lighting can be tricky because an object that looks good with one light may look worse with another light setup. Check your object using different numbers and positions of lights to make sure you don't have problems! The most common problem is a glossy specularity which looks great in a still but feels like shiny plastic when your object moves. It takes multiple renders from different angles to spot this, or better yet, a fly-around animation.

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