frudawski

writeldt

The writeldt function saves a given luminous distribution curve as EULUMDAT file.

Note: EULUMDAT files are usually normalized at 1000 lm luminous flux, the luminous intensity should therefore be given in cd/klm.

I_{\textrm{norm}}\left(\gamma\right) = I\left(\gamma\right)\cdot \frac{1000}{\Phi_{\textrm{luminaire}}}

See also: readldt, ldc2Phi

Usage:

writeldt(file,ldt,'normalize')

Where:

ParameterDescription
fileSpecifies path and filename.
ldtIs the ldt struct containing the EULUMDAT file information:
ldt.name  – gives the luminiare name information
ldt.header – contains the file header information
ldt.anglesC – contains the C angles
ldt.anglesG – contains the angles
ldt.I – contains the corresponding luminous intensities
'normalize'
(optional)
Will perform the normalization to cd/klm before saving the EULUMDAT file.

Examples

Read, adjust, save and plot a ldt file:

% Import Lambert ldt
ldt = readldt('lambert.ldt');
% Adjust luminous intensity distribution
ldt.I = ldt.I.*cosd(ldt.anglesG);
ldt.name = 'luminaire';

% Save in new .ldt file
writeldt('newldt.ldt',ldt,'normalize')

% read new .ldt file and plot luminous intensity distribution
newldt = readldt('newldt.ldt');
plot2dldc(newldt)

See also: readldt, plot3dldc

Result:

References

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.

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