Physical Camera Vs Color Mapping?

[cogombo]

I was wondering if I only use still images without DOF, what's really the difference adjusting the illumination level with Physical Camera (F, ISO, speed...) and with Color Mapping?

Normally I can achieve de same result if I increase de physical camera's parameters or if I increase de color mapping parameters.

What's the rule I must apply? What's de difference between F, ISO, speed and dark and bright multipliers? (if I don't use DOF, of course).

Thanks a lot.

[Franz78]

hi cogombo,
here some link to learn some basik concept

http://en.wikipedia.org/wiki/Exposure_value
http://en.wikipedia.org/wiki/Exposure_%28photography%29
http://en.wikipedia.org/wiki/Tone_mapping

and anyway, think about exposure control of phycam as a toll to incrase and decrase the amount of the light you can see in image.
color mapping is only a system to manage contrast and traslate the color of image in a specifc color and gamma contrast.

i prefer for most of case to set phy cam and use color mapping to adjust the tuning of contrast in some specific area of image.

Ciao
Franz

[cogombo]

Ok, thanks for the answer. I think I must test more to understand this better.

[choppir]

I also stuggle with this.

I don't know if i need to set camera settings 1st, then mess around with colourmapping and sun to get the image brighter/darker, or doen't it matter?

Like the image i'm working on now, i want ligter overall, but then the sun is too bright! If i make the sun lower then, the image is way too dark....


I don't know what setting to play with to get the 'global' image lighter overall. At the moment i play with Camera settings or gamma, but still i don't get it right.

choppir

[stefan]

hi

both things work together. they do completly different things.

colormapping is a kind of very advanced contrast setting, a bit like choosing different photo papers. or like adjusting all to the was the human eye sees light.

the phycam does make it lighter or darker only through iso or shutterspead.
also it adjusted the dof. if you have low fstop like 2, you have much more dof than when u have a high fstop like 22. like real cameras.
also the scale of the scnee of course influences the dof. tiny objects have much more dof than big ones. again like real cameras or film.

by the was, the phycam is only optional for pro-users, you can also use the normal camera without tag for the beginning.

cheers
stefan

[Laurent]

Here comes the dumb question: couldn't those physical camera setting like F, ISO, speed and white point be re-adjustable real time on a rendered image?

[simonw]

the answer is yes and no.

things that alter the exposure could be tweaked in real time but altering the f-stop is problematic if you are using the physical camera (as the f-stop alters the depth of field).

the best thing to do is to render to a high dynamic range image as you then have the full power of photoshop at your disposal and can adjust the exposure and colour balance there.

the 'problem' with VRAY is that it adjusts the sampling intelligently according to the brightness of the image so that as you tweak the colour mapping rendering images will give you differences beyond just brightness - the smoothness of the gi, AA, shadows and reflections will also change according to the settings in the DMC sampler.

cheers, simon w.

[nycL45]

... render to a high dynamic range image as you then have the full power of photoshop at your disposal and can adjust the exposure and colour balance there.

"High dynamic range image"? Is that high resolution or multi-pass? Since it seems to overlap with HDRI, a little more info please. Thanks.

[stefan]

High dynamic range image=hdri

cheers
stefan

[nycL45]

...the best thing to do is to render to a high dynamic range image

Hi Stefan,

Aha! When Simon noted "render to a high dynamic range image", he meant "render *with* a high dynamic range image". Yes?

Leonard

[Fluffy]

No, the output must be 32bits if you want to tweak to the full depth using High dynamic range.
So I think he meant "render a high dynamic range image", since using HDRI as illumination, or even textures won't yield the depth necessary if the final render outputs only 8 or 16bits image.

[nycL45]

So, 32 bit output = more to work with in ps. That helped. Thanks for the clarificatiions.