The readldt function imports the luminous intensity distribution curve from .ldt EULUMDAT files.

Note: EULUMDAT files are usually normalized at 1000 lm luminaire luminous flux, the luminous intensity are therefore given in cd/klm. For example, the luminous Intensity distribution curve (LDC) of a luminaire with 4000 lm needs to be adapted by the factor 4.


ldt = readldt(file)


ldtIs the return struct containing the EULUMDAT file information:
ldt.header – contains the file header information
ldt.anglesC – contains the C angles
ldt.anglesG – contains the \gamma angles
ldt.I – contains the corresponding luminous intensities
filespecifies the path and filename


Open and plot lambert.ldt file:

ldc = readldt('lambert.ldt');

See also: plot2dldc


Note: to select a *.ldt file via popup menu, use the following code snippet:

[file,path] = uigetfile('*.ldt');
% select lamber.ldt EULUMDAT file %
ldt = readldt([path file])

Open lambert.ldt using a popup dialog window and plot in 3D:

ldt = readldt('lambert.ldt')

See also: plot3dldt


Ian Ashdown: Thinking Photometrically Part II. 2011, (LIGHTFAIR 2001 Pre-Conference Workshop).

Axel Werner Richard Stockmar: EULUMDAT – ein Leuchtendatenformat für den europäischen Beleuchtungplaner. In: 9. Gemeinschaftstagung der Lichttechnischen Gesellschaften Deutschlands, der Niederlande, Österreichs und Schweiz, pp. 641–644, Nederlandse Stichting voor Verlichtingskunde, 1990.

Leave a comment

* I accept the use of cookies as well as the terms in the privacy policy. I accept that data provided by me is processed and saved. I know that comments are saved and published after review.