# integral of radiation in one point

Dear list,

I have question that I hope you'll help get my head around.

I want to calculate the overall illuminance on a point in space that is,
regardless of directionality.

I have made some simplified 2d sketches for clarity.

As I understand a radiance sensor point in rtrace will have cosine
related sensitivity (image01)

If I am to place two coincident with opposing normals (image2) I'll miss
on contributions from the sides.

Rotating the normals by 90 degrees at a time (figure 3) and summing
contributions might not work either because will overestimate diagonal
contributions (figure 4 ).

So I'm not getting too much closer to the solution...

Is there something that I am missing here?

Any light on this will be appreciated,

Best,

Giovanni Betti

Hi Betti,

I think you can refer to Greg's answer to my question "Spherical sensor."
in Vol 94, Issue 11.
Good luck!

Minki

···

Date: Tue, 8 May 2012 12:42:03 +0100
From: "Giovanni Betti" <gbetti@fosterandpartners.com>
To: "Radiance general discussion"
<radiance-general@radiance-online.org>
Subject: [Radiance-general] integral of radiation in one point
Message-ID:
<6F5225D6E15F954BB4E58EC25F6736C308CFCE7D@corp3005.CORPORATE.
FOSTER.NETWORK>

Content-Type: text/plain; charset="us-ascii"

Dear list,

I have question that I hope you'll help get my head around.

I want to calculate the overall illuminance on a point in space that is,
regardless of directionality.

I have made some simplified 2d sketches for clarity.

As I understand a radiance sensor point in rtrace will have cosine
related sensitivity (image01)

If I am to place two coincident with opposing normals (image2) I'll miss
on contributions from the sides.

Rotating the normals by 90 degrees at a time (figure 3) and summing
contributions might not work either because will overestimate diagonal
contributions (figure 4 ).

So I'm not getting too much closer to the solution...

Is there something that I am missing here?

Any light on this will be appreciated,

Best,

Giovanni Betti