IDA Glare Measurement Program

Glare Measurement, Glare, Light Trespass




To develop a system to quantifying glare that can easily be field verified. 


Glare; The first questions that have to be asked:

What is glare?
We all know it when we see it, but can we define it and can we measure it?
How do we address it and its control in policies and ordinances?

How does it arise? Where do we see it? From what type of installations and sources? When do we see it? How to address it and minimize it? Who to address is and cure it? How to assure it doesn't arise in future installations? How to retrofit installations to eliminate it or minimize it? Intensity of the source? Local or surrounding contrast with the background?

Glare is easy to identify, but is very complex. For example, what are the different types of glare? Discomfort, disability, annoying, blinding, obtrusive. How does it depend on the locale or lighting zone? By surrounds and background? By source size (arc source or large sources) Dependence on viewers age and eyes?

We are interested in your answers to these questions and others relating to glare. It has been proposed that using a maximum luminance value of 1200 cd/m2 would be a suitable maximum value to control glare. What are your thoughts on this?

Email us with your suggestions and inputs on glare.

Glare Measurement, Glare, Light Trespass



Preliminary Experiments Using a Digital Camera to Measure Commercial Light Sources. 



This is an introductory report on experiments performed to explore the issues involved in using a digital camera to make images that can be used to measure the brightness of commercial light sources.  Interest in these measurements is a consequence of our desire to learn more about techniques and methods for defining, measuring, and characterizing glare associated with various light sources.  With development of a successful protocol, International Dark-Sky Association (IDA) members should be able to collect large numbers of images of geographically distributed light sources that can be measured for brightness, as well as evaluated for glare.  Experience with such a protocol is described in this report.


Full Report in PDF .


Glare Measurement, Glare, Light Trespass Glare Measurement, Glare, Light Trespass

Other IDA Studies

Other Light Pollution Research and Studies