Cache Irradiance generation

[NiGMa]

Hi guys, some help plz..

When I am generating a Cache Irradiance to "SAVE" to file it takes way too long, and then when I set it to "BOTH" load and save from file and choose another angle, it doesn't generate the new Cache Irradiance map so its all splotchy. I generated one for a new scene and it took 8mins for 1million lightmapped/recieved photons, is this normal? its kinda slow to work this way, before i leave work i have to wait 8mins just to see if i have a good irradiance map, than another 8mins if i have to do it again with higher N number or whatever, this isn't very good for workflow. how do you guys manage the render times? I dont like rendering for hours only find that its splotchy, trying to get kray to work in our company buts its hard to get consistant results.

What influences how long it takes to generate a Cache Irradiance map? number of polys? strength of lights?

I can't use area lights in windows because I need to be able to see the pool and backyard through it, so i'm just using a skydome with high lumi polys. I just found out that if I make the skydome smaller instead of being km's in diameter than I get more photons into the rooms, which was good to learn.

Please help me get this sorted out so I understand.

Thanks

NiGMa

[NiGMa]

Another question, when I use the save GI to file feature with diffuse model set to photons estimate, does it have to be at the same camera resolution as the final render? or can it be smaller? I usually use 25% multiplier to get it done quicker, but maybe this is making it splotchy?

also, I just noticed that N number has a HUGE impact on the time it takes to generate a Cache Irradiance map.

[NiGMa]

Just did 8million photons with N-value at 10000, it took 43mins to save a 450x300res Cache Irradiance Map to file. Diffuse model on Photons Estimate on scene with 250,000 polygons, how can this be? its way to slow..

help plz..

[jure]

What influences how long it takes to generate a Cache Irradiance map? number of polys? strength of lights?

Well first of all do you realy need 1million lightmapped photons? The more the photons and the higher the N number, the higher the rendering time will be. I don't use that much lightmap photons in my scenes but some use even more than you. So perhaps try lower photon number and lower N to get faster calculation of irradiance.
Complexity of the scene will also influence calculation time so it's wise to turn off all the small objects like tables, chairs, sofas and other props when doing first "check out" renders. When you get good light and eliminate splotches you turn them back on and leave it to render.

It is also correct what you discovered about skydome. The best way is to make it as small as possible because large skydomes take longer to render.

Another question, when I use the save GI to file feature with diffuse model set to photons estimate, does it have to be at the same camera resolution as the final render? or can it be smaller? I usually use 25% multiplier to get it done quicker, but maybe this is making it splotchy?

Yes it can be smaller and that alone will not make it more splotchy. Your FG settings on the other hand may look good on 25% render size but at 100% you may find out that there are lot more splotches than you were able to see on small render.

Just did 8million photons with N-value at 10000, it took 43mins to save a 450x300res Cache Irradiance Map to file. Diffuse model on Photons Estimate on scene with 250,000 polygons, how can this be? its way to slow..

You have probably noticed that most of this time was taken by calculation od irradiance map. This is because you used such a high values. I recomend using much lower values (300.000 photons - N 3000)

[Single]

to Jure: I do thank you for a good council, and resolve if you please one additional question, how it is better to regulate quantity cells?

[jure]

To get more cells use lower "precache distance" value on the Photons tab and to get less cells turn the value up.