Stu's Long Hair Tutorial

In this tutorial I'm going to take you through modeling and rendering a fairly complex hairpiece for Steve Worley's Sasquatch plugin for Lightwave - the techniques I outline here are quite useful for generating a variety of hairshapes.

I will be mainly making use of Modeler's built in curves to create the initial guides, but these will ultimately need to be converted into 2 point polygon strands before Sasquatch will render them - for this I recommend using an excellent litttle plugin thoughtfully provided for free by Japanese plugin writer Moly.

I want go over a couple of points first.

While Sasquatch's long hair mode gives you ultimate control over shaping your CG hair it can be quite hard to get certain effects that the fur mode creates with ease - in particular I'm talking about the fact that hair is typically a *volume* and not a layer - this quality of hair is most evident at the scalp where it grows from the skin and at the hair tips, which in many modern haircuts tend to be feathered over each other creating a thick mass - the techniques I outline here have been developed to tackle both these 'problem' areas of Sasquatch hair design.

To start you will need to have some kind of head model prepared - we need the hair to grow out from the surface of the skin so a close match with the head geometry is necessary - put the head model in layer 10 so you can easily hide it and unhide it later.

In layer 1 make an open curve with about 7 to 8 knots then drag the knots around so that it roughly matches the screenshot - this curve represents the topmost layer of hair at the front of one side of the head - try to give it a natural wave shape and pay close attention to the start of the curve - it should start just under the skull near the right temple - let it finish reasonably high up the head (though for longer hairstyles you could bring it down a lot further).

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Copy and paste this curve then modify it so that it becomes the innermost layer of hair - this curve should start just above and in front of the ear - what you are trying to do here is define the overall volume of the hair between these two curves - note that while the two curves cover a wide area of the skull, the side thickness between them (red arrows) is fairly thin.

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Now copy paste in more copies of your original curve and model them so that they fill in the gap between the first two curves - you should need about 8 additional curves all together. Paste and modify each curve one at a time, making sure you try and describe a a gradual transition between curves 1 and 2 as shown.

Spend some time to make sure there is an even gap between each curve - also make sure that all the start points lie just under the skull suface of the head.

Similarly make sure the ends don't intersect the skull anywhere - but they should lie reasonably close the the skin.

Now copy all 10 curves and paste them slightly further along the head - spend some time realigning these curves, making sure that the start points lie just under the skull and that they don't intersect the skin along their lengths - don't worry if some of the outer curves cross over with the inner ones slightly - this can actually help the eventual hairstyle look a bit more realistic.

Repeat the last section with a new group of 10 curves - this time rotate them around the back of the skull slightly (in the top viewport) - you will probably need to spend more time here modifying them to compensate for the changes in the underlying skull geometry.

Once more paste 10 new curves - this time fully rotate them around the back of the head so that they lie flat in in the x plane - spend time modifying them and tidying the overlaps between each curve and its neighbour.

A closer view showing how the curves overlap each other at the tips (red arrow).

You now have enough curves to fill in one side of the hair completely with the railclone tool - but first you will use these four groups of curves to create the guide rails - select the top curve from each of the four groups then hide all the others.

Create a new curve that spans the start points of the four curves by selecting each of the four top points and using the create open curve tool - note the direction of this curve (red arrow) from front to back.

Now repeat the last 2 steps for each 'layer' of four curves starting with the next layer lower down - its usually helpful to hide the other curves each time - be very careful that you select the right curves here! - ie the 4th curve down in the front group must be connected to the fourth curve down in the other goups.

This is what it should look like once you have finished - you should have 20 new curves runing horizontally around the head - you will use these as guide rails to create the actual hair guides - cut and copy these to a new layer.

Go back to your original layer and select the entire *front* group of 10 curves - copy these to another layer as well. With this layer in the foreground and the horizontal guide rails you created in a background layer select rail clone from the menu - make sure that segments are set to length and uniform with a setting of 20 leave strength at 2 and switch off the scaling and orientation options.

You will probably need to tidy up the results somewhat - the magnet is a great tool for general reshaping - select the new hair curves and make the head visible - this allows you to make better judgements on reshaping the hair to match the skull properly.

We now need to repeat the whole operation on the other side of the head - while you can mirror the original four groups of curves over to the left side, its generally a good idea to at least reshape the front curves a bit to avoid too much symmetry.

Once you have made the guide curves and railcloned the hair curves for the opposite side of the head, use the magnet tool to make sure the two halves merge togther properly at the back.

You now have the two sides of the head done - to finish you need to add in a final piece over the top of the skull. Create a new group of curves that bridges the gap (5 curves only should do it), going from one side to the other - on the side that will merge in with the existing hair spend a bit of time making sure the new curves lie properly over the old ones (red arrows).

Using the same technique as before copy this group of curves and paste 3 times, moving them back along the head and and reshaping each time - check that the parting edge matches up with the gap left by the old side hair curves (red arrows) - also check against the head layer often to make sure the new curves clear the top of the skull.

Use these curves to make some guide rails the same way as before - you may need an additional middle set of guides here (as shown by red arrow) as the change in profile from front to back will be more extreme for the top than the sides.

Use the horizontal guide rails to rail clone the front set of 4 curves as before - you should end up with something like this image - use the magnet tool to blend the new piece of hair in with the existing bits and make any changes to overall hair shape.

Thats almost it - before converting to 2 point polys you need to jitter the back lower points slightly so that the hair will look more 'organic' and less 'manufactured'. a very small jitter applied to the whole hair piece can often help too.

Lastly some quick tips for setting up the Sasquatch parameters for the hair in layout - obviously long hair mode should be used and whatever surface name you gave the hair strands should be made active in the Sasquatch displacement panel.

Colour settings: - getting the colour right can be quite tricky sometimes - generally mid browns are easiest to do well - red hair is difficult to get the colour exactly right without it looking fake and blonde hair is highly dependant on lighting (and thus the hardest).

I've outlined the skew colour settings here - even if its not strictly 'realistic' use the skew colour and root/tip colours to get a bit of darkening at the roots - it usually helps especially with that tricky hair/skin boundary

Set courseness to around 30 to 40, length vary to something minimal like 5% - A bit of tip narrowing usually hekps too

The important thing to get right is the balance between the lock and clump settings - you want to use either the lock parameters (ie set clump count high, fibres per clump to 1) or the clump parameters (set clumps per lock to 1, fibre count high) or a combination of both to get the width of each lock right - right means just wide enough so that the locks begin to merge into each other as they leave the scalp and no more - use the settings shown here as a starting point for your own experiments

Some matting is usually desirable in both the lock and clump sections - beyond making changes to the model this is where you can alter the look of the hair - matting can also have a big effect on overall hair thickness.

Generally I use a classic 3 light rig to light most of my tests - ie a key light, fill and back light
all should be shadow mapped spots to work properly with sasquatch's shadow options -make sure all the shadow options are on in the pixel filter panel for the best effects.

Carefully position the backlight to get a nice specular sheen on the hair - you will probably have to do a few tests to get this right

You will need to lots of test renders to get everything right - make sure you look at the model from lots of different viewpoints as the hair can look remarkably different from various angles - you may have to make small changes to the hair model as well - the hairline where the hair joins the scalp can be especially difficult to get looking right sometimes - consider using a texture on the skin to help the blend.

I can be reached at stuart.aitken@axisanimation.com or on the Lightwave Mailing List on yahoogroups if you have any questions (though I may be too busy to answer all of them promptly sometimes).