Hi,

In a scene that I am working on at the moment, I have a scattering media
filled object that I am using to create clouds. There is one cloud that is
fairly close to the camera (about 200 units away). It's working fine. My
point light sun is lighting up the parts of the cloud that are in direct
sunlight nice and bright, and as the cloud gets deeper, it fades off to a
lightish grey at the base. It has the overall appearance of a nice fluffy
white summers day cloud.

However, when I started to add a second cloud I ran into a problem. My
second cloud uses the exact same media. It is around 1000 units away. Even
though it uses the same media, it traces much darker, its brightest parts
being a dark grey, and gets even darker after that, giving it the general
appearance of a storm cloud. The point light that I am using as a sun is far
enough away from the two clouds that the receive nearly the same angle of
light. The light isn't set to fade over distance or anything. I tried using
a second media for the second cloud with a lesser density, but it just came
out as a more ethereal storm cloud, with no discernible difference in its
dark colour.

Is this a bug in Povray's media? Why is my second cloud so dark? Is there a
way I can get my second cloud to be as bright as my first one (without using
extra lights)?

Thanks,

Equiprawn

Post a reply to this message

Perhaps the problem lies with the scattering method are you using. For example
Mie scattering is highly directional, i.e. viewpoint-dependent - media is
bright, when light shines straight through it towards the camera, but as the
difference increases, brightness quickly falls off. This resembles specular
highlights with low roughness value.

Margus

Post a reply to this message

Don't know if this is the problem, but be sure that your max_trace_level
is high enough (at least 1 bigger than the count of transparent surfaces
a ray have to pass through).

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

Post a reply to this message

Is the second cloud larger than the first? If it is, media is scale
dependant. An object scaled larger will appear to have a denser media in
it.

Post a reply to this message