Fw: Re: [Radiance-general] Shadow above highlight?

Thu Aug 13 15:00:48 PDT 2009

Here are the files and commands to run it for anyone who is interested.

	oconv -f -r 16384 sun_nosky_0621_12 p-cornell_9_quad_out.mtl
Sketchup2Radiance.rad>sun_nosky_0621_12_hres.oct

rpict -bv- -ab 1 -dp 2048 -ar 256 -ms 0.033 -ds .02 -dt .05 -dc .75 -dr 3 
-sj 1 \
-vf 0.vf -st 1.0 -aa .1 -ad 2048 -as 256 -lr 24 -lw .0002 -t 60 \
sun_nosky_0621_12_hres.oct  >062112-20.pic

ra_ppm -g 1 -e -2 062112-20.pic > 062112-20-t.ppm

--John Schwartz

==============Original message text===============
On Thu, 13 Aug 2009 16:58:44 EDT Greg Ward wrote:

Can you send me your scene description, so I can have a look at it?   
This is the worst possible timing for me, but you're going to get  
nowhere unless you share your scene files.  It's impossible to deduce  
what's going wrong from an image.

-Greg

> From: schwaj3 at rpi.edu
> Date: August 13, 2009 1:42:40 PM PDT
>
> Hmm, well no suggestions thus far has helped solve the problem I am
> having. I think it would help if I explain what I am trying to do. I  
> am
> attempting to validate radiosity calculations against a raytracer (in
> this case Radiance). I am doing this with a simple example of a box  
> lit
> only by direct sun and ambient bounces, so there is no sky  
> distribution.
>
> I have attempted many different rendering options, such as -aa 0 and  
> many
> other "high quality" level options as recommended in the Rendering  
> with
> Radiance book. These do not get rid of the problem. As you can see  
> in my
> gensky below, the sun shouldn't be approaching the zenith, as it has  
> been
> revealed can cause problems.
>
> I was reccommended to try using mkillum to turn the window into an  
> illum
> surface. I have attempted this, but it doesn't appear to do  
> anything, so
> I could be using it incorrectly? I am only using a single ambient  
> bounce
> in my calculations because the shadow is still there even on higher
> amounts, such as -ab 20. I decided -ab 1 would make it easier to track
> down the problem as well as take less computation time.
>
> Any more thoughts on what could be causing this? Could it be a problem
> with gensky similar to the zenith problem maybe?
>
> --John Schwartz
>
>> From: schwaj3 at rpi.edu
>> Date: July 27, 2009 3:41:40 PM PDT
>>
>> I am fairly stumped as to what is going on here. I have a box with a
>> square hole, 1/3 x 1/3 the width of the box, to allow sunlight into
>> my room.
>>
>> I am using the following gensky to attempt to only light the room
>> using
>> sunlight.
>> !gensky 6 21 12:00EST -a 40.77 -o 73.967 -g 0.0 +s
>> skyfunc glow sky_glow
>> 0
>> 0
>> 4 0 0 0 0
>>
>> sky_glow source sky
>> 0
>> 0
>> 4 0 0 1 180
>>
>> This picture was rendered using -ab 1
>> http://i639.photobucket.com/albums/uu111/radiancebox/radiance.jpg>  >> You'll note on this image, that there is a strange shadow on the  >  >> ceiling.
>> I am unable to figure out why.
>>
>> If I instead place a light in the room, also 1/3x 1/3 the size of the
>> box, I do not have this problem. This picture is taken from the
>> "back" of
>> the box, with the light on the ceiling instead of the floor. There
>> is no
>> gensky used on this picture.
>>
>> http://i639.photobucket.com/albums/uu111/radiancebox/Light.jpg  >> This  > picture was rendered using -ab 0>>> Changing the camera angle doesn't effect the shadow seen in the first
>> picture. I have determined that the shape of the window is not  
>> causing
>> the shadow, instead the highlight on the floor causes the shadow on
>> the
>> ceiling.
>>
>> If anyone can help clear this up for me, I would appreciate it.
>>
>> --John
>

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