HSV ESPONENTIAL AND HIGH RENDER TIMES....

[cocolas]

Hi all,

just courious if any of you ran into this before and if so what to do about it.
I render an scene w/ HSV exponential set to it's default settings (darker/brighter multipiers set to 1). And the time is 4:54 mins.

then I leave every other setting the same, but I change
darker multiplier to 1.28 amd bright multiplier is set to 1.15......this bumps up the render time to 7:27 mins.....all other settings were the same between the two renderings...

why is that??

thanks,
paul.

[J_Bug]

That makes sense though I would imagine for every bucket VRay has to spend some time calculating the new light values based on the renderings High Dynamic Range. I'm almost positive this is how it works after using the VRay Frame Buffer that was available in a previous build.

--Jon

[LuKa]

But why is this not the case when rendering with stored irr maps?

[J_Bug]

Maybe because it's not dealing with Color mapping per bucket but just one

--Jon

[losbellos]

yes but the opposite also true, if u use color mapping it could be also that the imap renders much faster, (especially overbrighted scenes)...

[egz]

I think Vlado said some time ago that the brighter the image is, the more samples VRay needs to take.

[J_Bug]

losbellos:
Do you mean if you use Color mapping to lower the brightness of a scene? I've done this in teh past and it seemed to produce a more realistic quality yet take longer to render. This seems somewhat analogous to taking a photo on a bright sunny day and having to stop the camera down for proper exposure. I wonder why Color mapping isn't in the Camera section?

egz:
I remember him saying that a while back but Color mapping shouldn't create more samples I'm not sure though, please correct me if I'm wrong. Isn't it applied after render, based on a pixels high dynamic range values?

--Jon

[cocolas]

I remember him saying that a while back but Color mapping shouldn't create more samples I'm not sure though. Isn't it applied after render, based on pixel values?

--Jon

that's exactly what I thought as well...aplied almost as a filter after the Imap has been computed...that's why I asked this question....and was kinda puzzled by the time difference....

paul.

[losbellos]

just try out, put something on a plane,for example few teapot or something, make simple enviroment-gi ligh setup, increase the multiplier to 2, render, then set hsv color mapping render again....
with HSV the irradiance map building time will be significantly less.
Dont know why maybe because of less samples need to take, but it works this way that is 100% sure. anyone can try this out.

[J_Bug]

cocolas:
Yeah and if that's true then think of it as a complex Photoshop filter being applied one time for each bucket and this could add up to an extra miute or so in the end.

Maybe not though

hey you misquoted me :P

Just kidding, that was before an edit.

You know what I've always thought would be useful is a section of the manual to explain technical details like this in laymans terms. Maybe even a set of logic statements to say this feature works with that feature but not so well with this feature. Or even those logic charts that says this effects this.

--Jon

[cocolas]

You know what I've always thought would be useful is a section of the manual to explain technical details like this in laymans terms. Maybe even a set of logic statements to say this feature works with that feature but not so well with this feature. Or even those logic charts that says this effects this.

--Jon

yeah, welcome to the club,man!!......I think there is a lot of us longing for that to happen........hehehe ...........vlado??.......

paul.

[vlado]

When calculating the irradiance map, VRay will take color mapping in account. This is useful, for example, if you have a very bright place in the scene, which gets clamped to white anyway, so there isn't much point in spending more rays there; or if you use the color mapping to darken the image, the required precision is also less; however if you brighten the image, VRay will need more rays to make sure that blotches which are not very obvious otherwise don't become so as they become brighter.

If you use a stored irradiance map, there is nothing to adjust, since the GI values have already been computed...

Best regards,
Vlado

[J_Bug]

Thanks for the clarifications Vlado. Man this is so cool how you've organized human perception into a nice little digital file. Don't know how many times I can say it but WOW

--Jon

[cocolas]

thanks much, Vlado........that makes sense!

paul.