Introduction

Some time ago, shortly after Sasquatch was first released, I created a series of images depicting various hairstyles done with Sasquatch’s fur mode - you can see the original images in the figure to the left.. Since then both Worley labs and myself have had many enquiries from Sasquatch users concerning how those images were created. The obvious thing to do was of course, to write a tutorial - so - finally, after much procrastination on my part, here it is.

Before starting there is one point I’d like to make:

While Sasquatch is a marvellous tool for covering beasties of all sorts in almost any kind of fur or hair imaginable, the fur mode (as opposed to long hair mode) does have some limitations when it comes to you’re average human hairstyle - I’ll bring this up again later, but I’d like to suggest from the outset that for most kinds of human hairstyles (and certainly medium or long styles) you will probably be better off using hair guides.

Having said that fur mode does give you some wonderful options for doing human hair. If nothing else this tutorial should hopefully give you a much better understanding of how the various fur parameters work together, and how you can combine them to create a wide variety of different hair looks.

Preparing the scene

The first thing to do is decide which parts of you’re model you want to grow hair from and unless you are doing a balding or bearded character this is usually fairly obvious.

Sasquatch gives you quite a few options for choosing how to do this, but for now we will be taking the easiest option, which is to paint a simple map. For complete control an unwrapped UV map of you’re head is probably best, since that more easily allows for painting around occluding geometry like ears, but I’ve gone with a very simple planar map projected down the x axis for simplicities sake here - see figure 02.

Take the map into you’re image editing application, and paint white for hair growing areas and black for bald areas.

I should point out that you could also use a weight map to do this if you prefer, but an image-based map will give us more flexibility later on.

In Layout, load in the head model and the hair growth map then set up the scene for Sasquatch (i.e. add the Sasquatch plugins to the head models deformation tab and to the scene pixel filter tab).

I like to use shadows from the outset when setting up Sasquatch so make sure you also add some shadow-mapped lights (make sure you’re model is nicely framed by each one) and add the Sasquatch shadow plugin to the mesh surface as well.

Figure 03 shows my typical settings for the pixel filter panel.

Figure 04 shows the rough light layout I use for doing test renders (3 spots in all).

Applying Sasquatch

Open up Sasquatch in the head mesh’s deformation panel and make sure apply fur to all surfaces is the highlighted option.

Generally its best to map density to control the overall growth area - you can also use length, but I prefer to leave that option for fine tuning later - click the S panel to open up the density panel mapping options and apply you’re growth map image as a planar projection on x auto sized to the whole object as in figure 05. Don’t go too high on the applied density value right now, but do make sure the base density is 0% or you will have a very hairy model!

Close the density mapping panel and set the other fur options as in figure 06 - you can fine tune these options to suit you’re particular model but these values generally work well

Next define some basic colour and shading for the hair - see figure 07 - again you can play about to get different colours and looks, but these are a good starting point for mid brown hair with a natural sheen - blonde hair and very dark hair are harder to get right so its best to start off with something fairly neutral that will be light enough to show off the hair texture and definition.

Make sure that the salt and pepper aren’t too dissimilar and that hue/bright vary and clump inheritance aren’t up to high though - unless you are deliberately going for the streaked look.

Conversely a good bit of variation in the root and tip colours (darker at the root, lighter at the tip) generally looks quite natural and gives the hair added depth.

If you move the camera around the back (you’re traditional hairdressers perspective you might say…) and do a render right now you’ll get something like figure 08

Combing and texture

Obviously this isn’t quite what we’re after!

The next stage is where the fun starts as you play about with the numerous options that Sasquatch give you over styling, combing and clumping. This gets a bit daunting sometimes as there are a lot of options all of which can be mapped and are often highly interdependent - i.e. tweaking one parameter will often have quite a pronounced effect on others. This is perhaps the most difficult aspect of Sasquatch to master since on one hand you have to have a good knowledge of what each parameter does in isolation as well as how they work in concert to really get things working the way you want them to.

To begin, add a bit of combing:

Open up the combing panel and put the combing up to 100% - this will make all the fibres head downwards once they leave the scalp (as hair tends to do). However if you render now you’ll notice large bald patches everywhere - to fix this turn the maximum sleekness down to something nearer 85% - this stops the hair penetrating the skin surface so much.

Render now and you will see that the hair no longer dives down underneath the surface, but now still stands rather too proud of the skin to be natural - figure 09

The clumping of the hair is also a bit exaggerated for someone who presumably washes her hair now and again - this is also what is responsible for the rather patchy appearance (you will still be able to see plenty of skin underneath the hair)

Go to the clumping panel and set the options as in figure 10

I’ll explain some of these choices in greater detail since clumping has one of the most pronounced effects on the texture of the hair and hence is important for achieving any specific look:

Clump haircount basically controls how matted the hair is - think of this as a kind of hair gel control - the smaller the value here the finer and more evenly spaced the hair will be, larger values giving more of chunky matted look to the hair - generally somewhere around 20% gives a good ‘interesting’ texture to the hair, but for now we’ll turn it down to 10%

Clump size is fairly self explanatory - for human hair values of between 10 and 30% are useful - less or more than that and its starts looking a bit unrealistic

Matting controls how much the hair in each clump comes to a tip - I’d generally recommend sticking to quite high values here - i.e. above 90%

Matting skew on the other hand is best set a bit lower than default - this controls how quickly the hairs merge together (low values skew it towards the root, high towards the tip.) it also has a big effect on how thick and voluminous the hair looks - for high values you will usually have to compensate with higher densities (which are slower to render) or the hair will start looking thin again (though this is again dependant on clump hair count as well)

Lastly fibre wiggle, length vary and clump vary simply help randomise the hair texture a bit - you don’t want these set too high or the hair will simply look rather messy

Rendering now will give something like figure 11

Notice how the hair covers the skull much more effectively than before as well as looking a lot more ‘groomed’

If you look closely you’ll notice that there is still a bald spot at the top of the head - the fact that it’s at the top of the skull is no coincidence since the hairs are combed downwards - i.e. all the hairs are combed away from this spot - be aware that when using combing you’ll never get rid of this completely and unfortunately its always a little too pronounced to pass for the crown on a real head of hair - we can move it around though to a more realistic position at the back of the head and at the same time give the hair a bit more interest

In layout add a null object, call it comb and give it a rotation of about 30 degrees on pitch (negative 30 degrees if you’re model is facing positive Z)

Go into the Sasquatch combing panel and select the comb null from the bias controllers popup

Figure 12

You can see that the ‘crown’ has moved back a bit on the head and that the hair in general is slightly more swept forwards than before.

The general hairstyle is now much more realistic, but it looks a bit boring and regular - luckily Sasquatch still has a whole host of options to explore…

Styling

Time to go to the styling panel - turn down combing to 60% first since all the styling effects tend to be strongly influenced by combing, All the following examples show each effect in isolation so that you’ll get a better understanding of their individual effects - the original image at the top of this tutorial shows various examples of using them together to produce more useful results - more on that later.

The first option you will see is tangle - tangle normally randomises the initial direction of the hairs or clumps but since the initial hair direction is also controlled by combing (which is the stronger influence, the strength of its effect is inversely proportional to the strength of any combing applied

Figure 13 shows the effects of 100% tangle with a reduced combing strength of 60%. I rarely use tangle much when doing human hair - the other controls are usually more than enough to play with without trying to randomise things even more : )

Root droop and tip droop basically mimic the effect of gravity, tending to push the hair strands towards negative Y - however combing is also pushing the hairs downwards since we have set it to point in that general direction. The crucial difference with the droop controls is that they give more control along the hair length - they allow you to push the hair further in towards the head, without it diving beneath the skin surface. As their names suggest each control is biased towards one end of the hair or the other - generally you will want to have root droop set higher than tip droop

Droop is also essential for getting the hair to bend down when combing is NOT set to a downwards direction (e.g. if you were combing hairs along a dogs tail) - Figure 14 shows 75% root droop, 50% tip droop

Next up is curling which has a similar but noticeably different effect - while droop always curls the hair downwards, curling will curl the hair in a direction perpendicular to the general direction of growth - in this case since the direction is downwards the hair will curl along surface of the skin - again this will have the effect of bringing the hair closer to the skull

Curling is also a very strong effect - small doses go a long way. - Figure 15 shows just 25% curling

Curl vary will randomise the strength/direction of the curling through the hair and is therefore another option for bringing some natural variation into the hair texture - Figure 16 shows 25% curling with 50% curl vary.

Tip curl biases the curl towards the hair tips - it is based on the main curling value so you will need to have some curling active to use it - Figure 17 shows 25% curling with 100% tip curl.

Curl combing is one of the more interesting controls - it aligns the direction of curling to the combing direction and once again it is a modifier of the main curling value - its quite useful for making the hair ‘flow’ around the contours of the underlying mesh - Figure 18 shows 100% curl combing

Tangle, droop, curling and combing are highly interdependent attributes since they all effect hair direction in some way or another - this can be a bit of a double edged sword sometimes - on one hand it’s what gives Sasquatch its’ amazing versatility when it comes to designing different hair looks and on the other it can often be a bit of a tug of war trying to work out exactly which parameter you want to tweak to achieve a specific effect - usually it’s a combination of all of them!

They also have a big effect on apparent hair length, which is something to bear in mind - often you will need to tweak hair length to compensate for high values

Frizz and Kink basically add small and large-scale waves into the hair and are reasonably straightforward to grasp, but again their effect tends to ‘mix’ with the other styling options - Figure 19 shows 70% kink with a frequency of 200% - frequency sets the general scale of the wave relative to the hair length.

Many of these parameters will also accept negative values, which can often lead to interesting results…And then of course there’s mapping! All of Sasquatch’s parameters can be mapped which gives even more control, especially the fractal noise option which is very useful for subtly varying the effects throughout the hair mass. Do be aware though that mapping works at the surface level - i.e. it effects whole hairs at a time and does not vary hairs along their length - this is not always obvious especially as what you see is often an outer surface of hair tips and not the hair roots which is essentially where they are being mapped.

Another mapping type that is often overlooked is slope mapping - this basically varies an effect depending on how steep the surface that grew it is - since a head is basically a big sphere, slope mapping can often be quite useful - e.g. Figure 20 shows the results of slope mapping hair length which in this case gives a shaved effect

Here are a few more examples of combined styling effects complete with parameter values to give you a few places to start from:

Figure 21A

Clumping:
Hair count - noise mapped 15 -25%
Clump size - 22%
Clump vary - 60%
Matting - 98%
Skew - 50%
Wiggle &Vary - 10%

Styling:
Root droop - 80%
Tip droop - 30%
Curling - image mapped 10% - 30%
Comb curling - image mapped 10% - 45%
Kink - image mapped 10% - 50%
Kink frequency - 30%

Figure 21B

Same as above except:

Kink - image mapped 0% - 100%
Kink frequency - 70%

Figure 21C

As fig 21 except:

Curling 50%
Curly vary 15%
Tip curl 15%
Curl combing 100%

Figure 21D

Combing 25%

Clumping:
Hair count - slope mapped 10% - 30%
Clump size - 17%
Clump vary - 60%
Matting - 100%
Skew - 85%
Wiggle &Vary - 10%

Styling:
Tangle - 15%
Root droop - 80%
Tip droop - 30%
Curling - image mapped 50%
Curl vary - 30%
Tip curl - 14%
Comb curling - 100%

Figure 21E

Combing - 50%
Mohawk length map
Hair count - 26%
Clump size - 20%
Clump vary - 50%
Matting - 95%
Skew - 70%

Styling:
Tangle - 15%
Root droop - 15%
Tip droop - 10%

Figure 21F

Clumping:
Hair count - 23%
Clump size - 23%
Clump vary - 16%
Matting - 98%
Skew - 70%
Wiggle &Vary - 10%

Styling:
Root droop - 85%
Tip droop - 50%
Curling - 40%
Curl vary - 20%
Tip curl - 20%
Comb curling - 50%

The main thing though is to have fun experimenting yourself - there are too many things to tweak to give any hard and fast rules - If you start getting frustrated or confused about what’s doing what, its often useful to pull a few values back to zero in order to get a clearer idea of how they are effecting one another

Limitations

As I mentioned at the start there are a few limitations to using fur mode for hairstyles, of which the bald spot at the crown is relatively minor - you can always texture the scalp to hide it fairly effectively anyway.

A major limitation is overall length - fur is good for short hairstyles where you don’t have to change the direction of the hair much over its length. Even medium length styles where the hair would naturally start to become wavy will pose serious problems since there just isn’t any method for effectively controlling hair shape precisely without changing to guide mode

Shaping can also become a problem at the front of the head where generally even shortish hairstyles will typically be styled differently than the main body of hair - to pull it off the face for instance. You can use multiple combing bias controllers to have some effect here but even then control is limited.

This is a bit of a shame really because - as I hope I have shown - fur mode offers awesome capabilities for texturing the hair mass - the good folks at Worley Labs really have included almost every control imaginable for hair texture. Conversely if you use long hair guides which give excellent control over general hair shape, you loose a lot of the texturing power of fur mode (you’re basically reduced to clumping control) and to achieve the same kind of believable volume you need to spend some time generating the guides in the first place.

What we really need is some kind of combined method that will give the easy shaping of guides but retains the wonderful texturing of the current fur-mode - here’s looking forwards to Sasquatch 2!

Having gained an enviable reputation for his highly detailed CG characters, he has gone on to forge close links with leading 3D software developers, helping push the development of a new generation of 3D graphics modeling, animation and rendering tools.

The Japanese version of this tutorial was printed in the Japanese CG World and Digital Video magazine in issue 47.