HDR Output?

[Hydra]

I just discovered a program.
http://www.hdrsoft.com/

Essentially take 3 renders with different dynamic ranges (exposures), and this will merge it all popping out the dynamic range in the image.
http://introvertartist.com/Photomatix/

There's an open source program which can do the same;
http://qtpfsgui.sourceforge.net/

I notice that the plugin has EXR output. Would this help for creating high dynamic range renders?

[t_3]

... if you have a scene with high contrast, which would actually lead to overshooting i.e. background sky/hdr/windows/whatever when using high exposure, or darken other areas with less exposure, you even don't need to use an exr - 16 bit pngs or even an 8 bit jpgs would be sufficient to use this technique.

but it pretty much depends on the lightning of a scene; if everything is well-lit - as you would usually aim for when setting up lights for a rendering - the effect would be next zero. so, in 1st place, one needs to create a scene/light setup that matches a real-world scenario where there is no single useful exposure value to have everything equally lit.

if you have sthg. like that, you may still try to output a single exr (means 32 bit float values per pixel), and use something like camera raw to create 3 (or more) copies with different exposures and try that techinque from a single render - probably needs some experimenting...

[erik-nl]

I use untonemapped .exr output from Octane for practically all my renders.
This way I can fine tune their dynamic range in Photoshop by mixing different exposure-corrected 32 bit to 16 bit conversions.

I'll make one 16 bit conversion using Photoshop's 'Local Adjustment' method, usually +0.5 EV overexposed to get shadow detail.
Then I'll make another using the 'Exposure and Gamma' method, usually -0,5 EV underexposed to get highlight detail.
Next step is to layer the second one on top of the first, using 'darken' as mixing mode.
By adjusting the opacity of that dark layer I can then easily get the dynamic range compression I need, usually at about 70% opacity.
Contrast will typically be low, so a 'levels' adjustment layer goes on top to give the image a little more umpf.

If I need it I'll also export a 16 bit PNG from Octane, because those EXR's don't have any post-effects like vignetting and film response.
Depending on the effect I want it to have I'll choose an appropriate mixing mode and opacity for that PNG top layer in Photoshop.
A little bit of 'multiply', at about 20% opacity usually does the trick.

All this may all sound rather complicated, but I'm used to it and it just takes me a few minutes to set up and adjust.

So yes, I think .exr HDR output from Octane is a very useful thing to have!

Cheers!

Erik