HDR Environment Map Dynamic Range

[Meelis]

Hi

Because matching sun position for the HDR + sun combo, is very time consuming,
i started painting sun on HDR do get shrper shadows and caustics.

But i'm not sure about the EV dynamic range.
In Luminance HDR i can only generate HDR from images in the range of EV -8 +8.
And in Picturenaut after generating HDR and directly saving the image without going to tonemapping, it seems to preserve the dynamic range.
But the sun looks black after i reopen the hdr in Picturenaut. In irfanview it's not black.
Will this HDR work for LuxRender as environment map?
How much EV i need for reall sun?

Is this any good?
Picturenaut prints out :
dynamic range : 3217798279610147000000000000000000.000000
true EV span : 111.309700
max radiance : 7.28665e+031

[Meelis]

I looked it up from here http://en.wikipedia.org/wiki/Exposure_value
No need for ev -100.
EV 8 is 15 000 x brighter than EV -6

[Qantourisc]

My fix is to put the gamma to 1.4 (of the HDRI lamp) ... seems to work for me.
Personally i'm under the impression lux assumes the gamma of the input is 1, while those images seem to be taken for gamma 1.4 ... gl.

[Meelis]

I didn't take the images. I downloaded the HDR from http://www.hdrlabs.com/sibl/archive.html
What i did is tonemapped 3 different 8bit EV explosures from it and merged them later back together with super bright sun.
I upgraded to latest picturenaut and now my HDR looks fine.

Anyways i got with my camera shutter speed 1/6000 s directly to sun
and in shadow 1/30 s.
(1/30)/(1/6000) = 200 (sun is 200x brighter) 8 EV stops. HDR over 8 EV stops will probably burn too much over, or am i wrong?

[Qantourisc]

I know where you got them
Just try those with gamma 1.5

[Meelis]

I know where you got them
Just try those with gamma 1.5

Okay.
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Are there any free HDR curve editors. So i can tune white balance aso without loosing dynamic range too much?

[Rhys]

I know where you got them
Just try those with gamma 1.5

Okay.
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Are there any free HDR curve editors. So i can tune white balance aso without loosing dynamic range too much?

You can adjust teh gamma in the luxrender. But probably blender compositor can do other stuff in hdr.

[Qantourisc]

You can adjust teh gamma in the luxrender. But probably blender compositor can do other stuff in hdr.

But that won't be the same because that will affect more then only the sky hdr ?

[B.Y.O.B.]

You can adjust teh gamma in the luxrender. But probably blender compositor can do other stuff in hdr.

But that won't be the same because that will affect more then only the sky hdr ?

I think what he meant was to tune only the sky HDR in Blender.

[Meelis]

The gamma thing wouldn't work for that.
Anyways, i rendered with modified HDR and went back to default (original HDR file).
I have more overburning but reflections look like reall thing.

I think the HDR editors will display EV range wrong.
Maybe they only look some random individual brightest pixel, that wont affect the overall look that much when you render in Lux with that env-map.