Disney's Hyperion Renderer
disneyanimation.com
Disney's Hyperion Renderer
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Re: Disney's Hyperion Renderer
#2What's the difference between path tracing, ray tracing and photon mapping?
I'd never heard of path tracing before now and the video makes it sound the same as ray tracing/casting, but what I've read implies otherwise (but I'm not sure how). Clearly it's different to photon mapping, but what ever happened to that: Was it too computationally expensive for the pay-off?
Re: Disney's Hyperion Renderer
#3What's the difference between path tracing, ray tracing and photon mapping? I'd never heard of path tracing before now and the video makes it sound the same as ray tracing/casting, but what I've read implies otherwise (but I'm not sure how). Clearly it's different to photon mapping, but what ever happened to that: Was it too computationally expensive for the pay-off?
The way I understand it; ray tracing and path tracing are the same conceptually except for how so called 'global illumination' (GI) is calculated. Ray tracing uses a short cut that computes the value with an equation that can be applied efficiently to the entire image. Path tracing on the other hand calculates the GI by tracing not only direct rays from the camera lens bouncing off an object to the light sources but also follows indirect rays that bounce around multiple objects in the scene on their path from the camera to the light source.
Practically speaking path tracing is going to give you a more real to life image at the expense of a slower rendering process.
Re: Disney's Hyperion Renderer
#4What's the difference between path tracing, ray tracing and photon mapping? I'd never heard of path tracing before now and the video makes it sound the same as ray tracing/casting, but what I've read implies otherwise (but I'm not sure how). Clearly it's different to photon mapping, but what ever happened to that: Was it too computationally expensive for the pay-off?
Ray tracing is the art of tracing rays and detecting collision.
Ray tracing is used in photon mapping and path tracing.
With photon mapping you trace a ray from a light source and store the light energy for the area where the light hits an object.
With path tracing you ray trace a ray from the camera and every time you hit an object you check if you can see a light source from that spot. If true you return all the gathered energy back to the camera (pixel).
Re: Disney's Hyperion Renderer
#5Anyone have any insight as to why Disney would build a separate rending engine when they own Pixar and could use their renderman engine?
Re: Disney's Hyperion Renderer
#6The Pixar online library is a really great resource.
Re: Disney's Hyperion Renderer
#7Anyone have any insight as to why Disney would build a separate rending engine when they own Pixar and could use their renderman engine?
This article[1] implies that there's a lot of cross-pollination with regard to computer graphics research and technology within the movie/VFX industry. So my guess is a bit of friendly competition that keeps spurring new innovation (similar to the browser wars).
[1] http://www.fxguide.com/featured/disneys-new-production-rende...
Re: Disney's Hyperion Renderer
#8Anyone have any insight as to why Disney would build a separate rending engine when they own Pixar and could use their renderman engine?
This article[1] implies that there's a lot of cross-pollination with regard to computer graphics research and technology within the movie/VFX industry. So my guess is a bit of friendly competition that keeps spurring new innovation (similar to the browser wars). [1] http://www.fxguide.com/featured/disneys-new-production-rende...
Not backed by an article, but I'd assume there's also the factor of needing a new or different capability for an upcoming project, which would prompt the technicians to try something different without affecting in-flight projects. They can always share some of Hyperion with Pixar when Pixar is at a point to change things.
Re: Disney's Hyperion Renderer
#9Anyone have any insight as to why Disney would build a separate rending engine when they own Pixar and could use their renderman engine?
Because until last year when Pixar released PRMan 19 RIS, PRMan was not that good at ray tracing / path tracing - the REYES method of rendering and shading didn't scale as well for big complex scenes when global illumination and raytraced light occlusion was done.
The RSL shading language was also causing a rather large overhead of shading time as it was an interpreted language that could no longer amortise its runtime cost over a shading grid of points using SSE - in path tracing, you generally shade one point at a time per ray vertex, although you can batch them up in some cases (but without significant ray re-ordering and deferring, after the first bounce this becomes less and less useful).
Disney also use Ptex for texturing, which doesn't really like incoherent shading points, so that was another reason to put effort into doing large scale re-ordering of rays and batching them up.
Re: Disney's Hyperion Renderer
#10What's the difference between path tracing, ray tracing and photon mapping? I'd never heard of path tracing before now and the video makes it sound the same as ray tracing/casting, but what I've read implies otherwise (but I'm not sure how). Clearly it's different to photon mapping, but what ever happened to that: Was it too computationally expensive for the pay-off?
Ray tracing is a more generic term that covers rendering techniques which trace rays between a camera and a scene. Back in the day everyone used Whitted style ray tracers to render shiny metal blobs because secular reflections are trivially handled with ray tracing. Unfortunately other physical aspects of light like diffuse reflections were not handled by early ray tracing algorithms.
Kajiya introduced the rendering equation, a mathematical formulation of global illumination (takes diffuse, secular into account). It's a multidimensional integral equation. Unidirectional path tracing is an algorithm he introduced to solve the rendering equation. It uses several rays traced from pixels in the camera bouncing randomly through the scene. It's a Monte Carlo integration algorithm for solving the nasty integrals.
Photon mapping involves a pass algorithm tracing light from light sources into the scene, then a pass (like path tracing) gathering that light back at the camera. It better handles more complex light effects like caustics.