4 ms·

This is only true from a naive approach to visibility. With rasterization you can rasterize geometric values like normals and positions to an image buffer

This is only true from a naive approach to visibility. With rasterization you can rasterize geometric values like normals and positions to an image buffer and shade only what is visible. Rasterization in old versions of renderman would do a lot of shading that was thrown away once scenes became more complex. Real time games eventually followed a similar pattern and now do 'deferred shading'. Rasterization can also be used to cull polygons that aren't visible when they are going to end up hidden by opaque objects. In theory ray tracing the first hit visibility can scale better, but in practice that part isn't a big deal and rasterization will probably win anyway. Not only that, but the idea that more polygons will make something look better is another trap. High quality lighting and high resolution textures become more important once polygonal geometry has enough polygons to not have faceting artifacts.

dahart 7y ago
You make some good points, but culling doesn’t really work for complex on-screen geometry like foliage, hair, volumetics, crowds, etc, and games are pushing in those directions. Raster is currently cheaper for well tuned video game assets, that is true, but is not cheaper for film quality assets, and that’s where games want to go in the future. Filtering is a very important issue, and you’re right that more polys is not automatically better from a quality standpoint. Still, ray tracing can enable rendering of geometric complexity that is not possible with raster in real time, as long as you have a way to filter. Games aren’t yet really pushing on the boundaries of instancing, but they will down the road. The other appeal with ray tracing is being able to consolidate all the various tricks and algorithms into a single path tracing framework. Ray tracing architectures don’t need deferred shading (though they may choose a similar wavefront approach), and they don’t have a collection of difficult and separate ad-hoc methods for each effect they want (shadows, AO, reflections, indirect lighting, volumetrics, etc. etc.). Ray tracing gives you a unified framework where getting new lighting effects is easier to add, generally speaking.
- CyberDildonics 7y ago
  > but culling doesn’t really work for complex on-screen geometry like foliage, hair, volumetics, crowds, etc, and games are pushing in those directions. Just because something doesn't work in all situations doesn't mean it doesn't work in general. Games putting polygonal leaves and crowds full of furry creatures would be a waste, it isn't going to happen without level of detail. It is actually cheaper for film quality assets, but the camera visibility rays aren't where most of the time is spent. Still, things like REYES / renderman architecture decouples all the sampling required for motion blur and defocus so that the visibility samples don't have to be shaded. > The other appeal with ray tracing is being able to consolidate all the various tricks and algorithms into a single path tracing framework. My reply was about ray tracing not actually being faster than rasterization for first hit visibility in practice. I didn't say anything about ray tracing in general here.

dahart 7y ago

You make some good points, but culling doesn’t really work for complex on-screen geometry like foliage, hair, volumetics, crowds, etc, and games are pushing in those directions. Raster is currently cheaper for well tuned video game assets, that is true, but is not cheaper for film quality assets, and that’s where games want to go in the future. Filtering is a very important issue, and you’re right that more polys is not automatically better from a quality standpoint. Still, ray tracing can enable rendering of geometric complexity that is not possible with raster in real time, as long as you have a way to filter. Games aren’t yet really pushing on the boundaries of instancing, but they will down the road. The other appeal with ray tracing is being able to consolidate all the various tricks and algorithms into a single path tracing framework. Ray tracing architectures don’t need deferred shading (though they may choose a similar wavefront approach), and they don’t have a collection of difficult and separate ad-hoc methods for each effect they want (shadows, AO, reflections, indirect lighting, volumetrics, etc. etc.). Ray tracing gives you a unified framework where getting new lighting effects is easier to add, generally speaking.

CyberDildonics 7y ago
> but culling doesn’t really work for complex on-screen geometry like foliage, hair, volumetics, crowds, etc, and games are pushing in those directions. Just because something doesn't work in all situations doesn't mean it doesn't work in general. Games putting polygonal leaves and crowds full of furry creatures would be a waste, it isn't going to happen without level of detail. It is actually cheaper for film quality assets, but the camera visibility rays aren't where most of the time is spent. Still, things like REYES / renderman architecture decouples all the sampling required for motion blur and defocus so that the visibility samples don't have to be shaded. > The other appeal with ray tracing is being able to consolidate all the various tricks and algorithms into a single path tracing framework. My reply was about ray tracing not actually being faster than rasterization for first hit visibility in practice. I didn't say anything about ray tracing in general here.