Hi, Finally I am done with ABTs, thanks to all the people at GameDev. Now the next step is to have occlusion culling. To start with I will like to know what are the techniques available for the purpose and where can i find information on those techniques. I have read the Occlusion Threads in "Greatest Hits by Yann" Section, but I will really appreciate if someone can send me links, where I can find further information on the various techniques mentioned. Regards, Hussain

From what i've read the most useful occlusion culling techniques for real-time rendering are conservative image space techniques, if you do a google search on siggraph papers on visibility techniques, also check the one of the reference manuals on dPVS library which also describe most of visibility algorithms available to date.

I think Yann uses a modified version of the hierarchical occlusion maps (HOMs) algorithm, you can also find the original paper on google.

[Edited by - snk_kid on February 15, 2005 9:57:39 AM]

i've coded different occlusion culling algorithm and as far as i know
they have some glithces too, one is that you should separate your rendering geometry by the occlusion geometry , i mean you will end to have two maps for the same geometrical topology , one for rendering and one with a lower level of detail for occlusion , more over the occlusion culling itslef isn't handled very wel by the video board due to bubbles in the pipeline, so Yann and others
uses a software rasterizer , in parallel with the opengl pipeline, the advantage is that you might end up with a lower resolution and a fast rasterizer, i advice you not to render every single triangle, render a polysoup made of coplanar or nearly coplanar triangles, again, detecting in real time when an occluder is a good occluder could kill the fps, heuristics are performed based on projective size of triangles, with today's trend pushing more and more triangles, on occlusion culler is overloaded with choices not always trivial , topology itslef isn't an easy topic, if you can affor to draw your level two times, go with that, i personally gave up occlusion culling one year ago , and moved towards portal , and of course i'm working an a ray tracer in my spare time waiting for gpus to do it for me in real time.

Quote:Original post by ketek
i've coded different occlusion culling algorithm and as far as i know
they have some glithces too, one is that you should separate your rendering geometry by the occlusion geometry , i mean you will end to have two maps for the same geometrical topology , one for rendering and one with a lower level of detail for occlusion , more over the occlusion culling itslef isn't handled very wel by the video board due to bubbles in the pipeline, so Yann and others
uses a software rasterizer , in parallel with the opengl pipeline, the advantage is that you might end up with a lower resolution and a fast rasterizer, i advice you not to render every single triangle, render a polysoup made of coplanar or nearly coplanar triangles, again, detecting in real time when an occluder is a good occluder could kill the fps, heuristics are performed based on projective size of triangles, with today's trend pushing more and more triangles, on occlusion culler is overloaded with choices not always trivial , topology itslef isn't an easy topic, if you can affor to draw your level two times, go with that, i personally gave up occlusion culling one year ago , and moved towards portal , and of course i'm working an a ray tracer in my spare time waiting for gpus to do it for me in real time.

There's this thing called a period represented by a '.' that is used to separate sentences. Sentences are grammatical constructs that are used to delineate ideas. Paragraphs are used to organize sentances into relatively related subjects. Line breaks are used to separate paragraphs for easy readibility.

There, now you have no more excuses.

Please, with all the respect, Mr. Anonymous can we concentrate on the Graphics and not the grammar.
Regards,
Hussain

Thanks anonimous poster, since now i will be more carefull about my grammar
and thanks not lowering my user rate like someone of you did just because i gave a rude answer.

I use directx9 occlusing query with a dynamic algorithm. Do you think it s a good way compare with method quoted here ?

I use directx9 occlusing query with a dynamic algorithm. Do you think it s a good way compare with method quoted here ?

/

Well from my findings, so far, the software based methods are much better than the hardware based methods. Reason being, in hardware based methods there is a continuous communication going on between CPU and GPU. In software based methods you can execute your Occlusion Queries parallel to your Rendering i-e, during the time, GPU is busy rendering the current frame, you can do your Occlusion Calcualtions on your CPU.
Please correct me if I am wrong.

Regards,
Hussain.