Wednesday, 9 February 2011

Wetness Rendering Paper

I have my meetings with Prof Subodh Kumar on Tuesdays 11.30 am.
So i will update my blog at least before the meetings.

I am currently working on wetness rendering and my aim is to render wetness as realistically as possible in real time(30 fps). I am currently trying to implement the paper rendering wet material by Jensen. This approach uses photon mapping to render wetness. Since it uses photon mapping it is obviously not real time(Although i saw a paper on real time photon mapping).I have to somehow improvise and innovate it to real time. I am using a basic implementation of progressive photon mapping to help me render the images.

So what does this paper have?
It talks that in order to render wetness it has two models
  • Surface model.
  • Subsurface model.
In case of Surface model it talks about the amount of photons that pass through the layer of water.A thin film of water is on the surface of material due to wetness. The effect of this is given by fresnal's equations(I am confused about some of the concepts). This is obtained with the help of refractive indexes, the incident angle, the transmitted angle(actually the refractive indexes give the angles with the help of Snell's law).
 The Surface model is trying to simulate total internal reflection in the layers causing further absorption.

In case of Subsurface model it basically talks about subsurface scattering. In case of subsurface scattering light enters the object at some place of the object and exits at some other place. Inside the material light can be scattered or absorbed.
The scattering and absorption are given by scattering coefficient and absorption coefficient respectively. The scattering and absorption are given in units of cm-1 and helps us to decide each scattering event. The probability of absorption is given with the help of exponential distribution(some doubts in this area also need to be cleared).

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