Support for Light Path Expressions in Cycles
The benefits of supporting Light Path Expressions (LPEs) in a rendering engine are multifaceted. LPEs allow artists and technicians to control and isolate different lighting components in a render with great precision. This control enables fine-tuning of lighting in complex compositing workflows without the need to re-render entire scenes.
Here are some potential benefits of supporting Light Path Expressions:
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Enhanced Compositing Control: With LPEs, compositors can independently adjust direct lighting, indirect lighting, reflections, refractions, shadows, and highlights, allowing for more nuanced adjustments in post-production.
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Time and Resource Savings: Re-rendering complex scenes can be time-consuming. LPEs allow for adjustments to specific lighting paths without the need to re-render, saving both time and computational resources.
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Improved Troubleshooting: When rendering issues arise, such as unwanted noise or incorrect lighting effects, LPEs can help quickly identify the source of the problem because they can isolate specific lighting paths within the scene.
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Increased Creative Flexibility: Artists can use LPEs for innovative visual effects, such as creating render layers that only contain certain types of light or crafting special lighting effects that might be difficult to achieve with traditional render layer methods.
Currently, the rendering output layering provided by Cycles may not be friendly enough for compositing stages that require high levels of control. While Cycles' render layers and passes system offers some level of control, its functionality is relatively limited compared to other rendering engines that support LPEs. This limits the creative freedom of artists in the compositing phase and can lead to more compromises and inefficiency.
By introducing support for LPEs, Blender's Cycles would be able to offer flexibility and control on par with other top-tier rendering engines in the industry, further solidifying its position as a professional 3D creation tool. This would be a long-awaited feature for many professional artists and studios within the Blender community and would aid Blender's application in the film, advertising, visual effects, and animation industries.
1 Comment
I think artists find the pattern-matching style very hard to use and not at all what they want. In particular they would like an expression that returns the "same" thing whether or not there is a sheet of glass in front of the visible objects, or in a mirror reflection of the objects. Basically they would like to trace the ray until the "first diffuse object" and then get the object id, the shader, and maybe split it up by the contribution from each light. Obvously the "first diffuse object" is not well-defined, but patterns that have to change depending on the scene are not the solution.