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Tutorials LightWave 3D Creating Polygon Hair Qua Jan 26, 2011 1:43 am
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| by Elmar Moelzer |
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Since the excellent hair- tutorial by Stu Aitken for Inside LightWave® 6 (and 7), one question has been asked over and over again: How to put hair on that head? Given a bald female head may look sexy sometimes (a la Alien3), but it does not really fit my taste and probably not the taste of most readers of this tutorial. There are quite a few ways to do hair and probably the most popular solution is the use of Sasquatch(-light), the wonderful hair- plugin by Steve Worley. This solution certainly produces great and realistic hair, but it also has its disadvantages, which are due to the nature of these kinds of plugins. Because of it being a post- rendering- effect, it does not do raytraced shadows and reflections and it does not show correctly in refractions neither. This is why I decided to develop my own method for doing polygon- hair, based upon what I had learned from old techniques, but by using the new features of LightWave® 6.5+. This hair does not have the disadvantages of plugin- hair and it could also be used as a proxy together with Sasquatch(- light) to have something that will show in mirrors and to cast raytraced shadows on the body. This tutorial requires solid knowledge of LightWave®s tools and is probably not to well suited for beginners. It requires LightWave® 6.5+ and an image- manipulation- software such as Aura, PhotoShop or PSpro. Part1: Modeler I decided to use subpatches for my hair- strands, due to the fact that they require less geometry for the definition of the shapes an thus are easier to handle. The use of normal polygons might be more efficient, which would help decrease rendertimes, but would certainly increase the amount of work needed. Modeler with the head of my still hairless "Cornelia" in a background- layer (active layer 2):  Create a flat box with 7 segments in y- direction:  Create a UV- map with the following settings:  The result is a UV- map that is nicely laid out on the UV-grid:  Now go into subpatch- mode [TAB] and use the drag- tool to modify the geometry to look similar to this:  This is our very first strand. The area of the hair- root may stick into the head a bit, but the strand must not cut through the head anywhere else. You should try to have a bit more space to the head especially on the sides. Please copy this strand into a separate layer for later use. Now clone this strand and place the copies around half the head by moving and rotating them. Take care for the strands not to cut into the head anywhere. If you like you can modify the strands to fit the shape of the head a bit better. You do not need to pay attention to the shoulders- area yet, as we will do that later on. This may sound like a tedious task, but it isn't. In fact, it should not take experienced users more than 5 minutes to do this. I decided to put two strands behind the ear:  Now copy these strands into a new layer and move them down and in a bit. This will become the layer of hair closest to the head. In the best of cases this hair- layer neither cuts through the hair- layer above, nor through the head (this should be avoided at all cost). Again it may only stick into the head at the roots.  You can now delete the polygons that are completely inside the head:  I repeated this step one more time and placed this new copy right between the first two layers, a bit nearer to the first one, as I still had a lot of empty space left there. This way I got a bit more volume and I avoided holes through which one could see the head below. Basically one half of the head should be perfectly covered with hair now. If you like you can go on and add even more layers of hair, but I think that for this tutorial three will do the job. Please be aware that additional layers will dramatically increase rendertimes! Next we will pay attention to the shoulders- area. Again we do not want the hair to pass through the geometry of the body. If you are planing to use Skelegons for later animation with bones, you may very well leave the hair the way it is now. For this I would suggest to leave the "wig" in a separate layer and parent it to the head- bone later on. This way I avoid the hair- bones distorting the body by accident. The posing of the hair in Layout may be a bit more difficult than in Modeler though. Another way of doing the animation may be by the use of Motion- Designer. Preparation for that would be similar to the next steps, but with the difference that one needs more space to the body, for the hair being able to "fall" down on the shoulders more naturally. For this tutorial I decided to do the "posing" of the hair in Modeler by simply dragging around points. This is the result with all layers activated:  While I used to be pleased with the way the hair- modeling looked at this point, I realized during render tests, that something was still missing: Natural hair does not fall down that evenly. In fact long hair uses to break and splice (female readers may very well know what I am talking about). This creates shorter fibers that stand away from the haircut. What is not so loved by people, who pay a lot of attention to their perfect hairstyle, should still be of interest for us, for we will not want our haircut to look like being wet or fresh from the barbers. To get around this, we need another layer of strands, which will be on top of all other layers. For this we will use our very first strand of hair (the one we copied into another layer for later use), but his time we will need a lot of thinner strands, so we will have to use the stretch tool to make it thinner. This time there is no need to pay to much attention to the hair cutting through other strands and the way they are distributed over the head. These fibers will be very thin and here the count is more important than the precision. You may also use Modelers tools to get a bit more variation into them and to make them shorter than the other strands. Because of these fibers being a bit shorter than the other strands, there is no need to match them to the shoulder- geometry this time:  If you haven't done that yet, apply a new surface- name to every- hair- Layer. This way you can easily select every layer using the polygons- statistics (in case you would need it later on). Now you can copy all hair- layers into one single Layer and mirror them. Don't forget to use the DragNet (or other tools) to add a bit of variation to the other side to avoid obvious symmetry. The result of the Modeling- part should look similar to the one displayed below:  Here we clearly see the big advantage of creating a UV- Map right in the beginning:  Yes, it is still laid out perfectly! Despite the massive deformations and cloning we did to the geometry afterwards! Part 2: Layout, Surfacing, and Texturing First we will need a good texture for our hair- strands. It should look similar to the one here:  This kind of texture is easily done in Aura, PhotoShop or PSpro. I created it by stretching an image similar to the "FractalReflections"(from the LightWave® Content) in the y- axis a few times. A bit of contrast- adjustment and it was done. You may use the image on the left to complete this tutorial and as a reference for your own textures. Because of functions differing a lot in the applications named above, I really don't want to get into much more detail here. This texture is then placed as an imagemap into the following channels of the hair- surfaces: Specularity (invert Layer), Transparency, Bump (invert Layer)and Diffuse (invert Layer).  The projection- type is UV. The UV- map is of course the one we did in the beginning of this tutorial. If you want to, you can paint another texture for the color and apply it to the Color- channel, which will ad further variation to the hair. This is especially important to make brown, blonde or gray hair look more realistic. Because my "Cornelia" having her hair dyed red, I was able to drop that step. Basically a simple reddish color and Color Highlights set to 50% (Advanced Tab in Surface- Editor), proved to be sufficient. Don't forget to make the surface "Double- Sided" and to turn "Smoothing" on.  Now for the rendering: I want to admit that render times can be high. You also should use Anti-aliasing of at least Medium with Adaptive Sampling off, because of the hair- texture having a fine structure. Otherwise you might experience a Moiré- effect during animation.  Above you can see a very first test rendering (render time 6min 58 sec on a Dual 1Ghz P3 in 640 x480 with Ray traced Shadows on and Anti-Aliasing High). This looks like hair, but is still far from being perfect. It still lacks Volume and there are parts where one can see right on the head below. With a bit of fine-tuning and a few more layers, it will become a very nice looking "wig" though. To get a bit more variation into the strands I played a bit with the UV- map. I moved the UV coordinates for some of the strands and varied their width in the UV- window. I also modified their geometry a bit to make the hair less straight and to add more variation. This is the final result, I got after a bit more tweaking and a few more layers (6 layers in total):  I hope you enjoyed this little tutorial. For questions regarding this tutorial or LightWave® in general, don't hesitate to contact me. Good luck, happy rendering and god bless! If you'd like to contact Elmar, send email to: elmar-at-newtek.com |
