[Radiance-general] Evalglare - Luminance or Illuminance

[Bissell, Andrew]

Thanks Greg, very much appreciated.

Regards

Andrew
__________________________
Andrew Bissell
B.Eng(Hons) C.Eng MSLL MCIBSE MIET
Associate Lighting Designer
Cundall Light4
Direct: 0161 200 1235
Mobile: 07899 907 978
Office: 0161 244 5660
 Please consider the environment before printing this e-mail

-----Original Message-----
From: radiance-general-bounces at radiance-online.org [mailto:radiance-general-bounces at radiance-online.org] On Behalf Of Greg Ward
Sent: 02 October 2010 22:12
To: Radiance general discussion
Subject: Re: [Radiance-general] Evalglare - Luminance or Illuminance

Hi Andrew,

You definitely want a luminance image -- using -i would give you wrong results.  Evalglare should add up luminances with the appropriate weighting to get vertical illuminance at the eye.

Cheers,
-Greg

> From: "Bissell, Andrew" <a.bissell at cundall.com>
> Date: October 2, 2010 1:07:53 PM PDT
> 
> Sorry for what must be obvious questions.  I have just compiled evalglare for Linux and I have run a few test images albeit the images were very low res.  I have read various papers and posts on the net and seen the images referred to as luminance images and illuminance images.  So which is it?  Part of me says luminance as brightness is more relative to glare, on the other hand my understanding of DGP is that it measures illuminance at the eye.  Which led to me confusing myself over the type of image required.  Certainly if you try both, the results are different, however the images I am using are crude with just 1 bounce so that could easily explain the difference.
> 
>  
> 
> Also I read the luxeuropa2005.pdf on the evaluation method etc.  However I was still at a loss as to what the DGP results really meant.  E.g. if the DGP result is 0.4756 what does that mean.  The document talked about levels below 0.2 not being reliable. 
> 
>  
> 
> The other evalglare posts were useful wrt –vth and –vta, also the picture header.  Thank you.
> 
>  
> 
> Regards
> 
>  
> 
> Andrew
> 

_______________________________________________
Radiance-general mailing list
Radiance-general at radiance-online.org
http://www.radiance-online.org/mailman/listinfo/radiance-general

Cundall Johnston & Partners LLP is a limited liability partnership registered in England and Wales.Registered number OC300389.  
Registered office: Horsley House, Regent Centre, Gosforth, Newcastle upon Tyne, NE3 3LU
Privilege and Confidentiality Notice: Use of this email and any attachments is subject to the terms on our Website at http://www.cundall.com/email.htm 
If you cannot access these terms, please email terms at cundall.com with SEND TERMS in the subject heading or telephone +44 (0191) 213 1515 and we will send you a copy. 
--------------------------------------------------------------------------------
This email message has been scanned for viruses by Mimecast. For more information please visit http://www.mimecast.com