Indirect Illumination Observation and Tip

Indirect Illumination Observation and Tip

Post by Mike J. Wi » Fri, 17 Oct 2003 14:08:50


If any of you have ever seen strange dark spots blanketing your model
when using Indirect Illumination, I may have found a cure for your PW2
chicken pox.

Here is an image in which my room size is very small. In this case
the room is just large enough to encompass the model...
http://www.yqcomputer.com/

You can see how blotchy the dark areas are. If you look close, you
can see the spots. Sometimes they are very obvious.

Here is an image in which I enlarged the room by several hundred
inches...
http://www.yqcomputer.com/

As you can see, the larger room produces a superior image.

I hope this helps someone!

Mike Wilson
 
 
 

Indirect Illumination Observation and Tip

Post by B. van Wel » Fri, 17 Oct 2003 14:41:31

thanks for the tip.
in Sw 2003 the problem with a large room is , that it effects the
perspective of your object (how bigger the room the less perspective).
I had to adjust my perspective to a value of 0,5 to get a realistic looking
picture.
i havent tried it in 2004 yet .

regards,

Bram van Welzenis


"Mike J. Wilson" < XXXX@XXXXX.COM > schreef in bericht

 
 
 

Indirect Illumination Observation and Tip

Post by Paul Salva » Fri, 17 Oct 2003 15:24:15

Hey Mike,

Was your room a physical room or a PW2 room and did they include a
ceiling?

..


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Indirect Illumination Observation and Tip

Post by rrodrigue » Fri, 17 Oct 2003 23:18:26


Mike,

Thanks for the tip. I tested it this morning and it does work!!!
Paul I adjusted the settings to a PW2 room. I tried the ceiling
setting at 0 and other hieghts. The ceiling setting dosen't seem to
affect anything it's the length and width sizes that matter. It
dosen't even matter if you have the walls, floors or ceiling visble. I
started with a low number and then kept increasing my values by 100
until the spots went away.

What a great tip Mike. I have been struggling with this for a while.
Thanks for posting.

Rob
 
 
 

Indirect Illumination Observation and Tip

Post by Arthur Y- » Fri, 17 Oct 2003 23:24:19

I got that the other day, but the dots were on the floor. No matter what I
adjusted it would not go away. I will try the bigger room size. Paul, in
mine it was not a physical room that I created. I just used the floor and
offset it at a distance of 0.0"

I though that it was the fact that I turned on the shadow effect in the
lighting source, I dunno.

Is there an adjustment on how much persective you get, or is it just
standard default and thats it? Maybe there is some seceret setting
somewhere, cuz i have never been able to find it.
 
 
 

Indirect Illumination Observation and Tip

Post by Mike J. Wi » Sat, 18 Oct 2003 01:18:17

> "Paul Salvador" wrote...

For this demonstration, I used a spherical PW2 room to simplify things.
However, the dots also show up using the linear walls as well.

Mike
 
 
 

Indirect Illumination Observation and Tip

Post by rrodrigue » Sat, 18 Oct 2003 02:27:58


Arthur,

Set your view to perspective and then go to the pull down menu
VIEW--MODIFY--PERSPECTIVE. The smaller the value the greater the
distortion.
 
 
 

Indirect Illumination Observation and Tip

Post by Paul Salva » Sat, 18 Oct 2003 02:49:12

Adding to Robert, if after modifying the perspective value and the
perspective is still not enough for your physical room, use the
hide/show trick (you will have to re-adjust the perspective value).

http://www.yqcomputer.com/

..





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Indirect Illumination Observation and Tip

Post by Paul Salva » Sat, 18 Oct 2003 02:57:50

Ok. So I guess this means the scattered rays in a smaller room create
more noise and the larger refracted boundaries reduce that cross over
noise?

..








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Indirect Illumination Observation and Tip

Post by mike.mcder » Sat, 18 Oct 2003 05:13:28

this blotchiness is caused by a phenomena in mental ray

in the full release the environment or model space dictates how many
rays are generated thus if there are not enough rays you get
blotchiness you can overide this but it increases render time now the
bigger the model space the more rays need to be cast i am assuming
when they wrote in global illumination to pw2 they automatically
calculate rays based on model space this cures blotchiness

just a question though when you increase th model space does the
render tim increase
 
 
 

Indirect Illumination Observation and Tip

Post by Edward T E » Sat, 18 Oct 2003 22:46:58

It has not been my experience that the render time increases. If it is, its
just a second or two.
It was a very wierd discovery - better quality, no hit taken on time, just
by adjusting room size - even if the room is not visible or reflective.





I
and