Maya:NPR?

[LucentDreams]

Both blue and orange on my site ( http://www.cgi.third-era.com/~kaiskai/ under stills/3d ) were done using the same basic technique, though blue was not light dependent and orange was. Part of the reason the shader works so well though was because of the detail in Martin Krol's model. Its the same shader idea used on the penguins image to.

Basically there ar two shaders, and it could be donein almost any of the major apps I believe, the first shader applied used a falll of gradient with no interpolation, thus you get the hard transition from each colour, so I assigned three colours for tone colour and highlight. wanting to get a sort of marker effect, I went with black colour and light colour for the highlight, almost white. The advantage of using a fall off gradient is that it isn't light dependent, meaning if oyu want to cast a shadow at a slightly different angle you can, that shadwo is not where it technically should be considering the lighting on the tiger.

The second shader was a simple Fresnel shader, some apps might call it someting different, but basically it uses theangel of the surface normals to control what colour in a gradient shows up, most commonly used on reflections and transperency to control how much reflection there is or how transparent sometings according to its angle to a screen. using this in the alpha channel using a simple black to white gradient allows you to put any colour in either the luminance or colour channels of a shader. to define the colour of the line, luminacne if you want the line to always be that colour, and colour if you want the line to responde to light at all. I assigned the colour black since I wanted that marker and inked look. THe cool thing about this shader, if you apply it to a sphere it will make a perfect outline, but on flat shapes it really doesnt' so that very well, since a normal will be fairly flat and consisten one face typically end up all black. however, I took advantage of that to get some even nicer black areas. basically if a fairly flat surface is about 80 to 90 degreees away form the camera it will appear black I the apply this shader over top of the other shader.

These renders were done in Cinema 4D. I know the shader cn be done in both maya and max, and assume the LW and XSI oculd do the same as those types of shaders are fairly standard now.

Another technique which I used, seen here http://www.cgtalk.com/showthread.php?s=&threadid=45875 is basically increase the phong or blinn diffusion to something quite high like 160% then adding my main colour to the colour channel, a reallly dark version of that colour to the luminance channel basically to prevent the tone from being solid black, not needed if you want solid black. then hi the specularity, I made the overall width fairly thin, but set the height of the specualr to 100% and the inner width to a wider settings, I alsolowered the falll off of the specular as much as possible to get that nice sharp specular.

One thing a lot of people don't realise when using shaders for NPR or cel shaded effects, is that the way the model is made greatly effects how well it will work. for example my moose character has one flaw in his design when using these techniques. and that is that the muzzle is fairly flat on top, meaning I get a nasty black bulge i my line which doesn't work for the effect I wanted, hence there are no NPR renders of him there. The Tiger as I said works great because of the flatter surfaces and the detail of the model. I should not Iw ant in and did some post on those renders to get the nice glow on the highlights.

hope that helps a bit.

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