What is Non-photorealistic rendering?
Non-photorealistic rendering or NPR rendering is a style of 3D and 2D art that looks like stylized art forms rather than realistic or photographic looking images.
Many 3D NPR styles are influenced by traditional art mediums such as ink drawing and hand painting. Cell shaded comic book art or toon styles are very popular as are technical drawing styles for concept art, engineering, scientific and architectural visualization.
2D NPR styles are usually applied to photographs or videos to create artistic style renderings such as watercolour, oil, drawing and other artistic effects. They can use heuristic algorithms simulating the placement of brush strokes to build up the stylized image, or Neural Style Transfer algorithms (NST) which emulate a wide gamut of artistic styles from a database of visual examples.
I’ve written a few articles around the site touching on this technique and its use in Illustration workflows such as in using the G’MIC artistic stylize filter and programs such as FotoSketcher and Dynamic Auto Painter. Personally I still don’t think automated 2D styles are very nice looking on their own, but in a workflow situation that includes the artists real input with hand painting or drawing techniques they can be useful or inspiring starting points.
NPR is being used more and more in animation and Illustration techniques, the recent Netflix series “Arcane” is a great example of how 3D can be used in a more artistic looking way. The 3D models use hand painted stye textures.
The animators from Fortiche Studios have done a great job in creating a painterly animation style mixing 3D and 2D animation techniques. Their music videos for League of Legends are all brilliant as well.
Another well known example is Spider-Man: Into The Spiderverse.
It isn’t new mixing 3D and 2D art styles together in animation, Japanese Anime has been using NPR styled 3D for some time. Arcane and Into The Spiderverse do set a pretty high benchmark though, they look absolutely gorgeous and blend the technologies so well.
Some computer games like Ori and the Blind Forest and its sequel Ori and the Will of the Wisps also manage to blend 2D and 3D together to create gorgeous stylized art.
There are procedural as well as hand painted techniques for creating NPR styles in 3D.
Resources for creating 3D and 2D NPR styles can be found on the internet or directly in the software such as ZBrush NPR render styles. I’m not going to go into them in this article as it is more of an introduction, but I will collate and talk more about them in a future article.
Further reading:
https://en.wikipedia.org/wiki/Non-photorealistic_rendering
https://www.researchgate.net/publication/236973460_Non-Photorealistic_Rendering
