[Radiance-general] rtrace direction

[Vaib]

Hello everyone!

This is my first email to the group. :)

My queries are:

When the input to rtrace is lets say 0 0 0 0 0 1. (X,Y,Z origin = 0; X,Y,X
direction is from Up or 0 0 1) then:

1. Does it creates ONLY a single Ray from this point (0 0 0) towards
direction (0 0 1), in this case normal towards Zenith? Just to make sure I
am getting the right concepts of ray tracing.

2. If it is so, then output irradiance is from ONLY the Up direction (0 0
1), and not from any other direction?

3. If it is so, then: is it possible (may be a rarest of the rare case) to
get Zero irradiance at a point from a particular direction?

I am asking this because I am getting Zero irradiance at a vertical surface
inside the room when the direction given to rtrace is normal to this
surface. E.g for a point on North wall, the direction given is 0 -1 0. For
all the other interior surfaces I am getting some reasonable irradiance
values, but only for North wall its Zero. So my reasoning for this was,
since rtrace traces only a single ray from a point towards a particular
direction then it is possible (though rarely) to get zero irradiance from
that direction. I just thought to get your opinion on my reasoning.

All surface normals are towards inside of the room.

Thank you in anticipation! Hope I made my question clear.

Best regards,
Vaibhav Jain
www.vaibhavjain.co
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