Saving Irradiance map

[glorybound]

If I want to render a scene at 2048 X 1024 how low can I pre-render the Irradiance map and reuse it in the higher render? I haven't been utilizing a saved Irradiance map when I think I can.

[Da_elf]

hehhee. its the irradiance map limbo...
how low can you go
how low can you go
how low can you go
hehehe

[mmikee]

I just got through rendering IR/LC for a still at 800x600, and rendered the final image with the saved IR at 2k. It really depends on the scene, as
does most everything with Vray.

[glorybound]

IMAP

Hmmm... I'll play around and see how low I can go

[olitech]

...you can go 1/4 of the final....

eg: final=6000x4000, imap calc@ 3000x2000

final=720x480, calc=360x240

[DaForce]

unless my powers of math are failing me your numbers exhibit a reduction of 1/2 not 1/4

[CCS]

Semantics. Each dimension is 1/2, but the image actually is 1/4 the size. Count the pixels.

And... I'm not sure why people still render a small image then reuse the IR map. Unless I'm misunderstanding something, lowering the IR setting acomplishes the same thing, but much more easily.

For instance, a 320x240 image with IR of -3/0 that looks good will have the exact same solution as a 640x480 set to -4/-1, or a 1280x960 at -5/-2, or a 2560x1920 at -6/-3.

If I'm wrong, somebody set me straight, but I could swear Vlado has said as much. Plus, it seems to work just ducky in practice....

[DaForce]

True, half image resolution, quarter the pixels.

[Clifton Santiago]

@CCS: Yes, you are correct sir. There is no reason to half your render size when you can just lower your IR min/max settings by 1. And I remember previous posts where Vlado has said as much.

I have also done render tests to confirm this, and the IR calc time for say a 640x480 at -3/0 is almost identical to a 1280x960 at -4/-1. And the quality looks identical as well.