Radiosity (doubts!)

[doujay888]

I've been into radiosity for a couple of months now but I still don't

get the feel of it. I have some few questions with you guys.

 

1. When i do rendering in radiosity (interior) do i need to make use

of logarithmic exposure control or automatic exposure control?

 

2.I am using ies files for my radiosity lighting, however i am having problems

with the result of the rendering which looks YUK! is it because of the reflectance value which causes the materials of not having the exact effect?

(I always make use lighting override for my materialsand using metric units)

 

I have attached some wip's i have using radiosity and 2 images using standard

lights (file: standard1.jpg)

 

Kindly give me some hints, tips and tricks in radiosity coz im really poor on this

Thanks again!

[kicks]

[jucaro]

I think its looking fine. You only need to tweak the refine iterations.

 

Are you using final gather? That would help a lot, but at cost of extra rendering time.

[lievenstandaert]

They're not too bad.

You are using MAX/ADT-radiosity, right?

 

I'm still trying to figure out radiosity too, but here are my conclusions sofar:

(anyone: If I'm making mistakes her, please do correct me)

-I like radiosity as it allows me to get much more natural shadows (duh!)

-However, radiosity tends to make the images quite flat

 

Why?

--> when you use radiosity, direct shadows from your lights are included in your solution, so unless your radiosity grid is very fine you lose those crisp shadows. The result varies greatly with the type of shadow, but it seems I get to choose between very sharp shadows (raytraced stays sharp) or very blurred shadows. I LIKE SOMETHING SUBTLY INBETWEEN!!

 

--> You loose highlights! Firstly, only point light generate highlights. Area lights don't give you any either way. You can think of highlights as very simplified, faked reflections of light sources. Radiosity doesn't do these highlights as it counts on real reflections to generate those. But that takes a lot more time to render, and a lot of tweaking to get it right. In your image of the reception desk I would expect highlights on the floor and on the glass of the picture frames.

 

--> Radiosity doesn't do bump maps very well. In your image, the right wall seems to have some kind of bump, yet the shading on it is very smooth.

If you heave the time, render the same image using regathering, and you will see the difference! regathering is the only way I've found so far that solves this, but is TIME-EXPENSIVE

 

What I'm missing, and what took me a lot of time to figure out, is what the different light solutions (area, radiosity, point lights with area shadows,... )DON'T do. You know, you allways get these lists of features in the manual what they do, and what their advantages are, but I really would like to see a clear list of what they DON'T do.

 

 

Anyway, what I'm doing is experimenting with compositing different renderings in photoshop.

(radiosity + shading/highlights layer from a non-radiosity render.