POV-Ray : Newsgroups : povray.advanced-users : HDR and brightness : Re: HDR and brightness Server Time
23 Jun 2024 06:43:38 EDT (-0400)
  Re: HDR and brightness  
From: Thomas de Groot
Date: 24 Feb 2018 07:16:02
Message: <5a915782@news.povray.org>
On 24-2-2018 13:01, Thomas de Groot wrote:
> On 24-2-2018 12:09, Mike Horvath wrote:
>> On 2/23/2018 9:50 PM, Alain wrote:
>>> Le 18-02-23 à 13:18, Kenneth a écrit :
>>>> Mike Horvath <mik### [at] gmailcom> wrote:
>>>>> Can I achieve the same brightness using an HDRI sky as using a light
>>>>> source? Or are there limits on how bright a scene can be?
>>>>>
>>>>
>>>> I haven't yet used an HDRI image/image_map in a scene, but I would 
>>>> assume that
>>>> the maximum rendered brightness on-screen would be clipped to 1.0 
>>>> (typical
>>>> maximum white)-- or rather, as bright as your monitor can reproduce 
>>>> 1.0, just
>>>> like with any scene.
>>>>
>>>> The saved file is another matter, if it's saved as HDRI. (POV-Ray 
>>>> can do that,
>>>> right? I haven't read the documentation enough to know.)
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>> Yes, you can save as high dyamic range image. Just need to add +fe 
>>> (*.exr) or +fh (*.hdr) to the command line. Then, there is no clipping.
>>
>> I wonder if it would be easier to render my sky and fluffy clouds 
>> once, and then include it in subsequent renders as HDRI.
>>
> 
> I would not do that if I were you. The fine details of the sky/cloud 
> structures would be lost. The resolution of the sky dome is not that 
> good and those images are not intended for crisp backgrounds but for 
> (global) illumination.
> 

er.... I might contradict myself here because I may have misunderstood 
what you intend to do :-)

If you intend to build a spherical sky probe to be used as hdri/exr sky 
spheres in later scenes, then yes by all means, do that with a spherical 
camera. However, be aware of my comment above at the same time. I attach 
an example scene I made years ago to show what that means.

-- 
Thomas


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