todays match: photonmapping vs lightmapping

[Gijs]

Just did a quick speed comparison between light mapping and photon mappping. I am worndering where the difference in rendertime comes from. Any thoughts?

Is photon mapping just faster or is it that light map starts to be more advantageous with complex scenes?

P.S. photon map building took about 100 seconds, lightmap building took about 65 seconds.

[Gijs]

Little update:

This time lightmap 1200 subd. sample size 0.005, prefilter off, filter none
and (main difference for the rendertime) store light checked.

[Gijs]

continuing the monologue

Photon map with store direct light checked and retrace treshold = 2

[percydaman]

great tests. lightmapping should pretty much always be faster IMO. Thing about it though, its not view independant like photon mapping is. It bounces light from the camera, not from the light like the photon mapping.

[easee28]

thanks man good iniciative!
agree with you percy.

[nikulu]

Please forgive my Ignorance, since I don't have the guts to use the Public Beta version in our production, I don't know much about light mapping.

Here comes the stupid question: is photon mapping better and faster for animation than light mapping, because it is view independent?

[TutanMark]

Hi GiJs, nice test.

I did tests few days ago on lightmapping w/ Irradiance map.

I saw that , if i don't use filter at all... it's really fast, and got more details.

This is my test results (Excel file). U can get it HERE

This is the reference image, that is worster than yours , anyway it was only a test .. Get HERE

U could try those parameters (with some changing of course) on your scene to see what happens).

As u have seen, lightmap without prefilter and filtering is much faster.. and the final image is very clean.

See ya,
MG

[Gijs]

Here comes the stupid question: is photon mapping better and faster for animation than light mapping, because it is view independent?

Not necessarily. You can make a single lightmap for an animation (provided that no objects move, but this is the same for photonmap). You can read about it in the beta manual.

Speaking about the manual: The second lightmap test was made after reading the lightmap section again. It seems filtering is only useful when using the lightmap in the first bounce. Without filtering, the irradiance pass is faster and the endresult is cleaner.

The 'disadvantage' of lightmap not being view independant is more than enough compensated by the fact that it is so easy to setup and that it renders slightly faster.

Another advantage is that during the lightmap building, you can get a pretty good idea about the lighting already.

[percydaman]

not to mention, for the 1.5 release, lightmapping will work with all materials, not just vray mtls. If im correct, photonmapping still needs vray materials?

[s0real]

i think it's the other way round.
lightmap doesn't work currently with standard mats in the public beta.

[percydaman]

lightmap DOES work with standard maps if you have the latest 1.46.xx beta. Thats why I stated 1.5

[s0real]

oops...
sorry about that!

[nikulu]

to Gijs: Thanks for answering my quesiton.

[Infrared digital]

Has anyone used Light Mapping for an animation yet?

Is the storing of the light map the same ideas as the Irrad map? ie; render every 10th frame and save - then use the saved light map - also selecting Fly-through.

Excellent thread by the way !

regards

N

[Gijs]

I've used lightmap for animation before. You can read about it in the manual. Basically when you do so, it traces paths from the moving camera. This is what you will see in your viewport as well when precalculating the lightmap for the camera animation: it calculates the lightmap for the whole animation at once