[Radiance-general] integral of radiation in one point -spherical illuminance

[Giovanni Betti]

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:m.moeck at osram.com] 
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:gbetti at fosterandpartners.com] 
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

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