Christopher James Huff wrote:
>In article <web.3fc69a25b2b1540cca01221d0[at]news.povray.org>,
> "incognito" <nomail[at]nomail> wrote:
>
>> >You sure he said to do that? The usual arrangement has things the other
>> >way around. Light sources, even area lights, are very bad at doing
>> >diffuse light coming from large areas, such as a sky. Radiosity is very
>> >bad at doing light coming from more or less a single point. Radiosity
>> >for the sky and an area light for the sun would make much more sense.
>> >And if he said to use a light source, it wasn't pure radiosity.
>> >
>> If it clarifies any, here is the assignment:
>>
>> http://www.evl.uic.edu/aej/488/fall2k3.hw4.html
>
>Hmm...some apparent misconceptions. Radiosity is a lighting algorithm,
>not a rendering algorithm, and POV-Ray *always* raytraces. With POV, you
>can raytrace a scene with conventional lighting or monte-carlo radiosity
>(which itself uses raytracing to take the radiosity samples), but you
>usually use radiosity to complement ordinary lighting.
>
>An orrery is a poor structure to use for demonstrating radiosity. The
>planets will not reflect a visible amount of light on each other, will
>only have a slight influence on their moons, and it is a very
>inefficient way to simulate the sun. Radiosity will only benefit the
>rest of the scene, which is apparently secondary to the project. A
>typical example of a radiosity scene would be an outdoor structure with
>lots of shadows or a room with sunlight pouring in through a window.
>
>

Yeah, I was wondering why my radiosity scene was looking so pop art like.

I guess because it needed to be one scene for both raytracing and radiosity
due to time constraints, radiosity got short changed...

>> I just did this and it was not too dim. I think it does seem to be acting as
>> a light source now just maybe not very noticeable because I do have a
>> relatively light background. (My background ambient is set to only 0.4 and
>> the sun is set to ambient 1). I will go ahead and try the diffuse at a
>> higher value too since I would like it to be more noticeable.
>
>Ah...increasing diffuse will just make the scene brighter, it won't make
>the sun contribute more. You don't get much light from the sun becase it
>isn't much brighter than the sky...it is only a little more than twice
>as bright. The light from your sun does fall off with distance, which
>makes it insignificant compared to the light from the sky. Use a much
>higher ambient value for the sun, and it will shine brighter. Dimming
>the sky will make the effect more pronounced.
>

I just did this (the sun part) and it seems to have improved some. I've
decided against doing the sky part right now unless I find I have some
extra time left before this is due. The reason why is because I did some ad
hoc shading on objects based on that sky ambient value so I would have to
go back and change those too which will take some time.

Thanks again for the explanation. Appreciate it.

>Christopher James Huff <cja### [at] earthlinknet>
>http://home.earthlink.net/~cjameshuff/
>POV-Ray TAG: chr### [at] tagpovrayorg
>http://tag.povray.org/
>

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In article <cja### [at] netplexaussieorg> , 
Christopher James Huff <cja### [at] earthlinknet>  wrote:

>> http://www.evl.uic.edu/aej/488/fall2k3.hw4.html
>
> Hmm...some apparent misconceptions. Radiosity is a lighting algorithm,
> not a rendering algorithm, and POV-Ray *always* raytraces. With POV, you
> can raytrace a scene with conventional lighting or monte-carlo radiosity
> (which itself uses raytracing to take the radiosity samples), but you
> usually use radiosity to complement ordinary lighting.

Indeed, this sounds very much like the person who gave the assignment did
not read the POV-Ray user manual.  Oh well...

    Thorsten

____________________________________________________
Thorsten Froehlich
e-mail: mac### [at] povrayorg

I am a member of the POV-Ray Team.
Visit POV-Ray on the web: http://mac.povray.org

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