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Toon Shading a Building - Arnold for Katana

This short tutorial covers how to create an old, worn 'illustrative' sketch-style using the Toon shader to create the above image. It covers how to use Base Tonemap and Edge Detection in combination with bump mapping using a Noise shader to create a hatching effect. Thanks to Javier Garcia-Lajara Herrero for the use of his convent model.

  • Start off by assigning a Toon shader to the geometry.
  • Change the Filter Type to Contour (Arnold render settings). Without it, you will not be able to see the Toon Edge shading in the render.
  • Reduce the Specular Weight to 0 as we do not want any specular shading in the render.
  • Create a Skydome Light and render the scene. It should look something like this.

Edge Detection

  • Reduce the Angle Threshold to around 20 (Toon-> Edge Detection). This will give us more detailed edges around the geometry.

  • The Edges appear too thick and black. We can fix this by reducing the Edge Width Scaling to around 0.4.

Base Tonemap

  • The Base shading looks too dark for the illustrative effect that we want. We can adjust this by using a ramp to determine how the Base shading is affected by the lighting in the scene. Connect a black and white ramp to the Base Tonemap and increase the amount of white in the ramp until it looks like the image below.
Without Base Tonemap B&W Ramp > Base Tonemap

Hatching (Noise Shader)

Next, we will add a hatching style to the Toon Edge. To do this we can bump (or displace) the surface.

  • Connect an Arnold Noise shader to Geometry -> Normal (bump mapping) in the Toon shader.
  • Increase the number of Octaves to 8. Reduce the Scale in Y to 0.01. This will stretch the noise in the vertical direction and give the impression of a hatching effect.
Noise Scale: 1 Noise Scale Y: 0.01
  • Try experimenting with different Noise shaders/settings to get different hatching/stippling effects.
Cell1 Wispy
Billow Perlin

Various Noise shaders -> Bump Mapping

Final Rendering

  • Connect an HDR map or a Physical Sky to the Skydome Light.
  • You could also add a pale yellow Base Color and Emission Color to the Toon shaders to give a worn paper effect.
  • Try adding a similar shading effect to the sky using a polygon plane behind the geometry as used in this case.

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