5 ms·

Maybe I'm wrong but these fractals are made with raymarching not raytracing see ex: http://www.iquilezles.org/www/articles/mandelbulb/mandelbulb.htm http://www.

Maybe I'm wrong but these fractals are made with raymarching not raytracing see ex: http://www.iquilezles.org/www/articles/mandelbulb/mandelbulb.htm http://www.iquilezles.org/www/articles/mandelbulb/mandelbulb...

rndn 12y ago
The terminology is admittedly confusing. This is how I understand it: Ray casting: Determine intersection of a ray analytically Ray marching: Determine intersection of a ray by taking stepwise samples Ray tracing: Ray casting or marching along a light path (from the camera) Path tracing: Ray tracing with random experiments The first two are ray calculation strategies, the latter are rendering strategies. In ray tracing you usually have many simplifications and effects like in real-time rendering, for example direct light models. In path tracing these effects are the result from approximating the full rendering equation.
- 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 ago
    So path tracing is only used for the secondary rays and beyond?
    - Dave_Rosenthal 12y ago
      I 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 ago
        Such 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.

rndn 12y ago

The terminology is admittedly confusing. This is how I understand it: Ray casting: Determine intersection of a ray analytically Ray marching: Determine intersection of a ray by taking stepwise samples Ray tracing: Ray casting or marching along a light path (from the camera) Path tracing: Ray tracing with random experiments The first two are ray calculation strategies, the latter are rendering strategies. In ray tracing you usually have many simplifications and effects like in real-time rendering, for example direct light models. In path tracing these effects are the result from approximating the full rendering equation.

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 ago
  So path tracing is only used for the secondary rays and beyond?
  - Dave_Rosenthal 12y ago
    I 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 ago
      Such 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.