# Shadow nearby a fluorescent lamp

Dear all,

I'm doing UV analysis from UV lamp with radiance, and it looks like going
well. But i got a problem nearby the cylindric UV lamp. In my model, the UV
lamp passes through 2 walls, and there comes out a black shadow the wall
around the lamp. My rpict options are -i to see the surface radiation and
-ds 0.01. Could you explain why this problem occurs and how to solve it?
http://venus.iis.u-tokyo.ac.jp/personal/mkii/case00.gif

Thank you.

Hi Minki,

It is not clear to me what your geometry is supposed to represent.

case 1 - If you have 2 polygons representing "walls" and 1 cylinder
representing your source, where the cylinder passes through the
walls, you are going to have problems due to how the light source
sampling occurs along the linear source.

case 2 - if the geometry is supposed to represent a cylindrical
source that passes through a hole cut in each wall, then you
probably need to make sure that your "wall" geometry has a holes cut
out as needed for the cylinder to pass through.

Note also if what you are trying to do is model an actual fixture with reflector elements of some sort and simulate the output distribution, then
Radiance is probably not the right tool, you will need to look into a forward raytracer of some sort. I am sure that others on the list can advise on what might be an appropriate tool.

-Jack

Minki Sung wrote:

···

Dear all,
I'm doing UV analysis from UV lamp with radiance, and it looks like going well. But i got a problem nearby the cylindric UV lamp. In my model, the UV lamp passes through 2 walls, and there comes out a black shadow the wall around the lamp. My rpict options are -i to see the surface radiation and -ds 0.01. Could you explain why this problem occurs and how to solve it?
http://venus.iis.u-tokyo.ac.jp/personal/mkii/case00.gif
Thank you.
------------------------------------------------------------------------

_______________________________________________