Samuel Benge <stb### [at] hotmailcom> wrote:
> Hello Everyone,
>
> I've been trying to get HDR effects with the official version of POV-Ray
> (v3.6). I render a scene using the spherical camera and then use it as
> illumination for my objects. It has been working well so far. Each of
> these images took less than twenty minutes to render (see file name for
> minutes and seconds). Both were rendered with focal blur, which helps to
> reduce apparent image_map artifacts. One was rendered with radiosity and
> the other (metal shelf) was not.
>
> The background image was turned into a function, separated into it's
> individual R G B channels, tweaked with a 1.n poly_wave value, and
> intensified to suit the scene.
>
> So what do you think? Should I scrap this project and use MegaPOV? Or
> should I post the code?
>
> Comments and criticisms always welcome!
>
> ~Sam

It's a good start.  Anything that makes you think and improve your skills is
worth doing in my opinion, even if there are other ways of doing it easier.

One thing you need to watch for when doing this is with background scenes
with a large dynamic range (i.e. really high and really low areas of
intensity).  You will tend to lose a lot of the extreme intensities as they
get clipped by the output image format (this is especially noticeable and
important on the high end).  You decrease the intensity of the entire scene
for the background image and scale it back up in your second image, however,
you will tend to lose some of the low brightness details (it may turn out ok
for lighting purposes, but not as much for environment and reflective, as it
may be noticeable dpepnding on your scene.)  One thing you may try to do is
fake the hdr by, instead of creating just one environment map, render 3 at
different intensities, one very low to catch the dark details, one in the
middle and one at the high end to capture the upper light intesnities.
Then it is a matter of compositing these three images for you enviroment
function.  This can likely be done by modifying the code you use to map a
single image to accomodate interpolating 3 images.  I posted some code a
while back that attempts to do this internally.

http://news.povray.org/povray.binaries.images/message/%3Cweb.44468657f8d220636c4803960%40news.povray.org%3E/#%3Cweb.444
68657f8d220636c4803960%40news.povray.org%3E


-tgq

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