Dear Martin, Minki,

Thanks for the replies, I guess what I was trying to calculate (and to

whom dr. Martin refers to) is better called cubical illuminance; the

script Greg shared with Minki (thanks as always, Greg!) allows to sample

a full sphere in one go.

I think I have my ideas a lot clearer now, I'll just need to implement

either one of the approaches.

Thanks,

Giovanni

## ···

From: Moeck, Dr. Martin [mailto:[email protected]]

Sent: 08 May 2012 12:52

To: 'Radiance general discussion'

Subject: Re: [Radiance-general] integral of radiation in one point

-spherical illuminance

Hi Giovanni,

that is called spherical illuminance. As an approximation, you could

calculate 6 illuminance values (up, down, East, West, North, South) and

average them. Christopher Cuttle wrote a few papers on spherical

illuminance.

Regards

Martin Moeck

OSRAM

________________________________

From: Giovanni Betti [mailto:[email protected]]

Sent: Tuesday, May 08, 2012 1:42 PM

To: Radiance general discussion

Subject: [Radiance-general] 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