MASTER LIGHTING AND MATERIALS
Observe how light interacts with matter, and create advanced shading effects in Houdini and Clarisse
scivfx Light&material One, 2018
Learn how to
• Observe light and
• Add extra details to
• Use dynamics and other tricks to achieve richer shading effects
• Do experiments with real-world objects to understand how things work
This study scene was created for Isotropix to use as a demonstration of Clarisse. It is based on scanned objects, while the background is my photogrammetry and the statues are from
It is a trend in VFX and other Cg fields that artists use ‘uber’ shaders that deal with almost all of the usual material effects we see in daily life. however, there are some kind of phenomena that can’t be rendered with these shaders. additionally, working with these is more like being a dj – you mix together the different shading behaviours, which were originally created by shader writers. as the best djs are also musicians, we can get better results if we learn more about how light interacts with matter and also re-create these shading effects from scratch, even inventing new ways to add an extra layer of realism or a unique look to avoid results that are too standardised.
Observe directly We can achieve the most detailed and adequate shading effects if we do research, which includes direct and indirect observations. directly, we can observe different optical phenomena – one of the best times is during cooking and food preparation as a very wide range of material effects is there simultaneously. Just observe how flour or grounded seed gets darker but more specular with water, or how the egg white converts from a dielectric-like material to subsurface scattering one. another advantage is that you can touch and smell these materials, which is in contrast with the intangible nature of Cg. The shape of light We can use any display – a monitor or smartphone – as an arbitrary shaped and textured light source to study how the shape of it can affect the character of the lighting, especially the penumbra area of the shadows. this is similar to the lighting in Gravity and many other modern movies, just on a smaller scale. We can compare simple shapes like square and circle. You can imagine yourself as an ant walking through this blurry edge. the area of a square shape decays linearly from your viewpoint but the area decay of a circle – thus the incoming light amount – is sinusoidal in the function of the distance.
Real-time shaders in Clarisse we get the final shading in the 3d viewport because it is also raytraced. however, the viewport in recent houdini versions can show the shading and lighting effects with displacements very well, especially if we use the Principled shader. For virtual cinematography work, it’s important to see our scene with a decent level of lighting and shading but with smooth playback and interaction. in other cases it’s recommended to switch back to constant shading with wireframe in the viewport. this makes the scene more abstract and your eyes won’t adapt to the game-like visuals, which is an advantage for the rendering decisions later.