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  Contents

 Introduction
 Radiosity Mapping
 Dynamic Light
 Source Radiosity
 Dynamic Object
 to Static Object
 Radiosity
 Conclusion
 Printable version

 


  The Series

 Part I
 Part II

 

Dynamic Object to Static Object Radiosity

We now have a method for calculating the radiosity of dynamic objects, and for calculating the radiosity change caused by dynamic light sources. So now we should be fine and dandy, right? Well, seeing as this is a new section, and I have mentioned earlier that there is a third algorithm in this paper, I'm guessing that you know that we are not fine (although, perhaps not why).

The reason our radiosity solution is still not complete is because, although we have a method for calculating the radiosity that is caused from the static objects to the dynamic objects, we do not have a method for calculating the radiosity that dynamic objects contribute to static objects!

Well, there is a rather simple way of doing this. Basically, when you light your dynamic object, make certain that you maintain a list of lighting values for surface normals. In other words, average all of the lighting values out of vertices that have a surface normal facing approximately right, and do the same for the ones that are facing approximately left, back, forward, up, and down. You now have a nice little list of the lighting values for each of the main directions.

Now comes the part which actually approaches complex (but doesn't quite get there). What you do now is you make a light source at the center of the dynamic object (which is casting the radiosity), and for each light to surface vector that is calculated, you check to see how close it is to being up, down, left, right, etc. And you use the values that result from that directional check as weights. You then take those weights to determine what the lighting value of that particular light to surface vector is (based on the lighting values obtained from the grouping of surface normals).

The reason you don't just find one lighting value for the light source is because there is going to be different intensities and colors of light reflected in different directions by the object.

Next : Conclusion