Non Photorealistic Rendering

I found an interesting reading about NPR (non photorealistic) rendering while browsing through a student gallery of Bournemouth University. I've been doing some slightly research and read about NPR before, along with some half hearted attempts on making one.
It wasn't much to see in the gallery. Only a few low-res images were available. However the interresting part were the rapports which I assume have been written by the students. These rapports are downloadable and contains alot of information, references and tips & techniques about doing NPR renders. Some of them were very well written and definately a valuable reading if NPR would be in your interrest. Search around in their gallery and check out the links.
For those who does not know what NPR would be, check out the google image search results

Anyways, I took some time off my job related projects today to try out the NPR visual style. Since NPR means Non Photo Realistic, it basicly means anything which does not look realistic. So what is classified as NPR is hard to point out, because some might say "It does not look realistic enough, so that is NPR", or "It is not arty farty enough to be a NPR...". Anyways, my goal was to make something similar to what you would see in a childrens/artists skecth book. Something painted by hand, combined with a colored pen, water paint and what else it might turn out to look like.
As you might have seen in the examples of NPR, in combination with 3D. It means you are going to render out something which looks not rendered by a computer, and it is going to look like 2D.
Kinda ironic, cause it would be obviously faster for the average person to just draw the stuff by hand. But who cares. Its a fun challenge to mimic NPR :) Especially with a 3D software.


However, the mainlpart of NPR renders lies in postwork. There are a few ways and some plugins and special shaders made for NPR renders, but as most general 3d renders; postwork is recommended to give your work the little extra spice and eyecandy. The same goes to NPR rendering. My NPR test turned out to be mainly consisting of 1 important shader which I used in post processsing: The Outline, best known as Falloff. A hard falloff shader on my mesh gave the render a very noticable outline alike look, a good start. After mixing and duplicating this render as a layer in Adobe After Effects, I eventually approached a sketch alike look.

A second render pass were used to fill the outlines with something, so I used a falloff shader here as well with a more soft type of falloff. However I processed and reused this pass quite a few time like I did with the outline pass to make it to look like NPR. A third pass, the ambient occlusion were used to add more depth and contrast to the filling. However I had to be carefull with not overusing the AOC, otherwise it would be look too 3Dish.These three passes were the mainly ones I used from 3D rendering. However one more imporant "pass" where used which After Effects contributed to me with, and that were the CC Hair effect. It basicly gave the whole image pen stroke alike look. Didn't look good by default but with some composing of this element into the other passes, it turned out very and suprising usefull which gave me the final look I wanted to archive.My After Effects composition ended up with around 26 layers divided on 4 pre-comps. All that from only 3 3d rendered passes to archive one of many styles within NPR. Hmm interresting.
Since I did this in After Effects and not in Photoshop, it also means it can be used in an animation of an animated render of a 3D mesh. Where each frame would look like its own unique hand drawed figure on an unique sheet of paper! However thats more work than I intented to archive, but I did have a good attempt on the animation :) Might post it sometime later!
Oh yeah, and one more thing. Creds to whoever did the 3D model of the horse. I just found it somewhere for free for a very long time ago.

Enjoy NPR!
-mog