Given that subsurface scattering violates the typical assumptions of BRDF by allowing light to exit at different points from where it enters, how do rendering algorithms account for this complexity?
brianqch
The picture of the milk makes me wonder how the material of liquids behind a transparent surface interacts with light. I assume that we do have to include how light interacts with the material within to a certain extent if we want to keep it visually accurate. How costly is this to model? One idea I had is to count the material within as another surface that would interact with light differently than the outside.
jbf11
@brianqch I think the idea is to capture all of this interaction within the liquid through the BSSRDF. However, the BSSRDF is not just a black box, and still has to be computed (or measured experimentally). I think you are right that we need to model (perhaps a priori) light transport in the medium to generate the BSSRDF or collect data. Then, we can call on it for rendering and it will work for any perspective/angle/scene lighting/interaction with other objects. Your example of liquid is interesting, though, since if the liquid is dynamic in a scene, then we need to recompute the BSSRDF for each frame or have a model that gives the BSSRDF during the deformation.
rahulk29
The picture on the left shows a bunch of light bounces, but I assume that for liquids like milk, there is a continuous refraction of milk rather than discrete bounces. Is this correct?
theflyingpie
I create 2D portraits, and when rendering realistic skin, subsurface scattering is a really important concept to keep in mind, as skin layers are semi-translucent. Subsurface scattering is also the reason wax sculptures can be so realistic.
Edge7481
Regarding the earlobe render, would this require additional geometry (like a mesh of the blood vessels) within the ear or is it just all mapped on the surface?
sihuaren
In the subsurface scattering reflection model, the amount of outgoing light scattered at one point on a surface may depend on the light incident at a different point.
Given that subsurface scattering violates the typical assumptions of BRDF by allowing light to exit at different points from where it enters, how do rendering algorithms account for this complexity?
The picture of the milk makes me wonder how the material of liquids behind a transparent surface interacts with light. I assume that we do have to include how light interacts with the material within to a certain extent if we want to keep it visually accurate. How costly is this to model? One idea I had is to count the material within as another surface that would interact with light differently than the outside.
@brianqch I think the idea is to capture all of this interaction within the liquid through the BSSRDF. However, the BSSRDF is not just a black box, and still has to be computed (or measured experimentally). I think you are right that we need to model (perhaps a priori) light transport in the medium to generate the BSSRDF or collect data. Then, we can call on it for rendering and it will work for any perspective/angle/scene lighting/interaction with other objects. Your example of liquid is interesting, though, since if the liquid is dynamic in a scene, then we need to recompute the BSSRDF for each frame or have a model that gives the BSSRDF during the deformation.
The picture on the left shows a bunch of light bounces, but I assume that for liquids like milk, there is a continuous refraction of milk rather than discrete bounces. Is this correct?
I create 2D portraits, and when rendering realistic skin, subsurface scattering is a really important concept to keep in mind, as skin layers are semi-translucent. Subsurface scattering is also the reason wax sculptures can be so realistic.
Regarding the earlobe render, would this require additional geometry (like a mesh of the blood vessels) within the ear or is it just all mapped on the surface?
In the subsurface scattering reflection model, the amount of outgoing light scattered at one point on a surface may depend on the light incident at a different point.