HDRI lighting?

[d_ray]

i would like to know how do you use HDRI 360 images for lighting and for background ?

-do you use HDRI textures with the vray/sky and add a texture?
-mapping.
- what kind of settings do you use for ''color space'' . SRGB,gamma corrected or linear?

[nizu]

Re: HDRI lighting?

Hi,

-do you use HDRI textures with the vray/sky and add a texture?

Yes, you can but keep in mind sky textures of any kind will not emit direct light , they still can light the scene but only if you're using GI.
(they don't emit rays, but they're 'seen' by GI rays.)

To have a direct-light emitting sky, use a dome light . (i haven't tested the mapping yet)

EDIT : i see the mapping for dome lights and HDRis is being discussed in the main VB2.5 thread right now .
And mapping for dome light is w.i.p.

-mapping.

Afaik , most HDR panoramas use Latitude-Longitude mapping which should translate to "spherical" in VB UI .
(Confirmed : the standard "LL" a.k.a. "lat long" 360° panoramas are called "spherical" , if yours have top and bottom of the panorama , no need to adjust the tiling as in BI renders)

- what kind of settings do you use for ''color space'' . SRGB,gamma corrected or linear?

Depends , and it's tricky.. The theory says HDRis should be linear .. but that's just a standard , not always respected. (and makes no quality / practical difference with HDRis , both sRGB and Linear can be used to save an HDRi )

If you can check the supplier of the HDRi and see what they say about their images , will save you headaches !

You can check by looking at the HDRi image , either use a image viewer like HDR Shop 1.0 (EDIT: fixed name ) or PS , to simplify the process.
Or Look at the render , but can be deceiving as the brightness multiplier can alter the look of the image.

So indipendently from the viewing tool, you should make sure you're looking at the 'flat' hdri :
brightness 1 , no camera exposure , no exponential color map , no software gamma correction , no HDRI exposure corrections etc..

If you're looking at the 'flat' image: a linear image will look dark and contrasted (then specify 'linear') an sRGB HDRi will look normal (leave it to sRGB)

Some viewer tools will assume the HDRi must be linear and will correct the gamma by default : in that case a linear HDRi will look normal , and an SRGB will look overbright with washed colors.

Yes, it's confusing ... but the HDRi is such a flexible format ..and this is the downside.