To enable people to perform visual tasks outdoors both effectively and accurately, especially during the night, it is essential to provide sufficient suitable illumination.

The physiological glare that is generated directly by the luminaires in an outdoor lighting system can be determined with the GR observer employing the CIE glare

rating method. The GR observer is designed exclusively for calculations in outdoor projects.

GR glare calculation

To calculate the GR value, it is necessary to have a reference measuring surface in order to take the ambient luminance into account.

To add a new GR observer, go to “Insert/Measuring object/GR“. With your first click on the floor plan or the 3D view you select the observer's position, and with the second click you

specify the observer's viewing direction. The observer is placed at a standard height of 1.2 metres, and the nearest measuring surface is taken as the reference measuring surface.

The new GR observer is inserted underneath this reference measuring surface in the scene tree.

GR observer beneath the reference measuring surface

The reference measuring surface can be changed at a subsequent point in time by pulling the GR observer node to a new measuring surface in the scene tree with the Drag&Drop function.

The following parameters can be set for the GR observer:

Viewing direction: this determines the viewing direction in degrees, with 0 degrees being north.
Angle -: this delimits the viewing direction in the negative direction (in the counterclockwise direction).
Angle +: this delimits the viewing direction in the positive direction (in the clockwise direction).
Increment:  this shows the distance in degrees at which the observer is measured.
Inclination: this shows the inclination of the observer between -90 and +90 degrees. With a positive angle, the observer looks upward, with a negative angle, the observer looks downward.
Observer's age: age of the observer in years.
Correction factor: this is the factor for adjusting the luminance.
Rho: the reflectance of the ground beneath the observer in percent.

Please note: If the reflectance of the ground is adjusted, this value must also be changed accordingly.

If a GR observer is selected, the observer tools will appear in the ribbon bar. The observer's field of vision can be checked here with an animation. To do this, you should open the 3D view

(F3 key) and click on the Start button. The different viewing angles will now be shown successively in the 3D view. The speed of the animation can be changed using the controller in the

ribbon bar. If the GR observers are to be positioned according to the DB guidelines, the DB Guidelines button can be clicked.

Observer tools

After calculating the scene, the output for the glare rating can be opened via the output tree under "Calculation results/glare rating". In the sketch, the area affected by glare is shown in red.

The position, the direction and the maximum GR value are documented under the sketch.