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- Extremely efficient rendition curved surfaces of average to large size; that is surfaces covering more than a few pixels on the image.
- High quality motion blur and depth of field are extremely fast. This is because the shading calculation is decoupled from hiding calculation.
- Displacements are rendered at a lesser cost than in path tracing (micro-polygons).
- Efficient at rendering fluids because of screen space under-sampling.
- Efficient rendering of millions of particles.
- Performance almost independent of oversampling (pixel samples). This makes it easy (and fast) to render images without noise and without aliasing.
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- Looses performance when rendering densely tessellated geometry (i.e. objects with a density of hundreds or thousands of surfaces covering just a few pixels).
- Not suited for rendering scenes with high "pixel complexity" (e.g. a crowd seen from afar).
- Motion blur shading is only an approximation. For example, a spinning wheel will have its specular highlight blurred along with other details on the wheel, whereas the highlight should remain sharp.
- Takes more memory when used alongside ray tracing (for GI for example). This happens because we need ray tracing structures alongside REYES structures.
Path Tracing
Pros:
- Good Efficient at rendering densely tessellated geometry and dense scenes (forests, crowds, etc).
- Massive instancing allows for memory efficient rendering of trees/crowds and other redundant scene elements.
- Shading is usually sharper because shading is performed at each sub-sample (and not per pixel as in REYES). Although it is possible to make REYES shaper by increasing the Shading Rate, it is usually not done (as it affects performance). Whereas the Path Tracer do not have options to reduce the shading rate.
- Scales better than REYES with increased number of cores.
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