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Hmm, I think some of those definitions are a bit off. Let me try: - Ray-casting is the general technique of using ray/object intersections (usually to solve a
by Dave_Rosenthal 12y ago
Hmm, I think some of those definitions are a bit off. Let me try:
- Ray-casting is the general technique of using ray/object intersections (usually to solve a graphics problem). Could be via analytical solutions or not.
- Ray-marching refers to using an iterative technique for computing ray/object intersections. This type of strategy is used for these 3D fractals.
- Ray-tracing creates an image by casting rays for each pixel in the image (from the camera).
- Path-tracing is one of many random ray-tracing techniques. It averages across many random deep bounces of rays following light paths to accurately solve for lighting.
In this case, the ray-tracing casts rays against the 3D fractal via ray-marching and uses path-tracing to compute accurate lighting.
- rndn 12y agoSo path tracing is only used for the secondary rays and beyond?
- Dave_Rosenthal 12y agoI think think that's kind of a philosophical question. Wikipedia, for example, explains path tracing as integrating over incident light on a surface. You could either think of that as incident light at a point on a virtual film/sensor plane behind a lens or incident light on the first object you hit in the scene.
- ska 12y agoSuch techniques are often generally known as "Global Illumination". Often in physics based rendering you are attempting to estimate the BSDF (bi-directional scattering distribution function, often broken into T, transmission and R reflection) parts. This gets complicated by interactive media and subsurface scattering (i.e the photons go into a material and bounce around) but in the simple case of a surface interaction you are estimating an integral over solid angle for all light interactions. Monte Carlo path tracing is one way to do this estimation.