frudawski

# egrid

The egrid function creates a two-dimensional coordinate grid for illuminance measurements, depending on the size of the measurement area, see standard EN 12464-1. The procedure was proposed 1992 by Axel Stockmar.

Usage:

[x,y,nx,ny] = egrid(d,b,border,mode,[nx ny])

Where:

Examples

Illuminance measurement grid for an area of A = 5~\textrm{m} \times 4~\textrm{m}:

[x,y] = egrid(5,4)
plot(x(:),y(:),'k+')
grid minor

Result:

x =

0.3080   0.9343   1.5606   2.1869   2.8131   3.4394   4.0657   4.6920
0.3080   0.9343   1.5606   2.1869   2.8131   3.4394   4.0657   4.6920
0.3080   0.9343   1.5606   2.1869   2.8131   3.4394   4.0657   4.6920
0.3080   0.9343   1.5606   2.1869   2.8131   3.4394   4.0657   4.6920
0.3080   0.9343   1.5606   2.1869   2.8131   3.4394   4.0657   4.6920
0.3080   0.9343   1.5606   2.1869   2.8131   3.4394   4.0657   4.6920

y =

0.3080   0.3080   0.3080   0.3080   0.3080   0.3080   0.3080   0.3080
0.9848   0.9848   0.9848   0.9848   0.9848   0.9848   0.9848   0.9848
1.6616   1.6616   1.6616   1.6616   1.6616   1.6616   1.6616   1.6616
2.3384   2.3384   2.3384   2.3384   2.3384   2.3384   2.3384   2.3384
3.0152   3.0152   3.0152   3.0152   3.0152   3.0152   3.0152   3.0152
3.6920   3.6920   3.6920   3.6920   3.6920   3.6920   3.6920   3.6920

Illuminance measurement grid for an area of A = 5~\textrm{m} \times 2~\textrm{m} and resulting number of points in x and y dimension:

[x,y,nx,ny] = egrid(5,2)

Result:

x =

0.3080   0.9343   1.5606   2.1869   2.8131   3.4394   4.0657   4.6920
0.3080   0.9343   1.5606   2.1869   2.8131   3.4394   4.0657   4.6920
0.3080   0.9343   1.5606   2.1869   2.8131   3.4394   4.0657   4.6920

y =

0.3080   0.3080   0.3080   0.3080   0.3080   0.3080   0.3080   0.3080
1.0000   1.0000   1.0000   1.0000   1.0000   1.0000   1.0000   1.0000
1.6920   1.6920   1.6920   1.6920   1.6920   1.6920   1.6920   1.6920

nx = 8
ny = 3

Number of measurement points in x and y dimension for a grid area of A = 50~\textrm{m} \times 25~\textrm{m}:

[~,~,nx,ny] = egrid(50,25)

Result:

nx = 16
ny = 8

Illuminance measurement grid for an area of A = 5~\textrm{m} \times 4~\textrm{m} and a peripheral border of 0.5 m:

[x,y] = egrid(5,4,0.5)

Result:

x =

0.7500   1.2500   1.7500   2.2500   2.7500   3.2500   3.7500   4.2500
0.7500   1.2500   1.7500   2.2500   2.7500   3.2500   3.7500   4.2500
0.7500   1.2500   1.7500   2.2500   2.7500   3.2500   3.7500   4.2500
0.7500   1.2500   1.7500   2.2500   2.7500   3.2500   3.7500   4.2500
0.7500   1.2500   1.7500   2.2500   2.7500   3.2500   3.7500   4.2500
0.7500   1.2500   1.7500   2.2500   2.7500   3.2500   3.7500   4.2500

y =

0.7500   0.7500   0.7500   0.7500   0.7500   0.7500   0.7500   0.7500
1.2500   1.2500   1.2500   1.2500   1.2500   1.2500   1.2500   1.2500
1.7500   1.7500   1.7500   1.7500   1.7500   1.7500   1.7500   1.7500
2.2500   2.2500   2.2500   2.2500   2.2500   2.2500   2.2500   2.2500
2.7500   2.7500   2.7500   2.7500   2.7500   2.7500   2.7500   2.7500
3.2500   3.2500   3.2500   3.2500   3.2500   3.2500   3.2500   3.2500

Illuminance measurement grid for an area of A = 5~\textrm{m} \times 2~\textrm{m} with an odd number of points in x and y dimension:

[x,y,nx,ny] = egrid(5,2,0,'odd')

Result:

x =

0.2778   0.8333   1.3889   1.9444   2.5000   3.0556   3.6111   4.1667   4.7222
0.2778   0.8333   1.3889   1.9444   2.5000   3.0556   3.6111   4.1667   4.7222
0.2778   0.8333   1.3889   1.9444   2.5000   3.0556   3.6111   4.1667   4.7222
0.2778   0.8333   1.3889   1.9444   2.5000   3.0556   3.6111   4.1667   4.7222
0.2778   0.8333   1.3889   1.9444   2.5000   3.0556   3.6111   4.1667   4.7222

y =

0.2000   0.2000   0.2000   0.2000   0.2000   0.2000   0.2000   0.2000   0.2000
0.6000   0.6000   0.6000   0.6000   0.6000   0.6000   0.6000   0.6000   0.6000
1.0000   1.0000   1.0000   1.0000   1.0000   1.0000   1.0000   1.0000   1.0000
1.4000   1.4000   1.4000   1.4000   1.4000   1.4000   1.4000   1.4000   1.4000
1.8000   1.8000   1.8000   1.8000   1.8000   1.8000   1.8000   1.8000   1.8000

nx = 9
ny = 5

Illuminance measurement grid for an area of A = 5~\textrm{m} \times 2~\textrm{m} with a given number of points in x and y dimension:

[x,y,nx,ny] = egrid(5,2,0,'std',[5 3])

Result:

x =

0.5000   1.5000   2.5000   3.5000   4.5000
0.5000   1.5000   2.5000   3.5000   4.5000
0.5000   1.5000   2.5000   3.5000   4.5000

y =

0.3333   0.3333   0.3333   0.3333   0.3333
1.0000   1.0000   1.0000   1.0000   1.0000
1.6667   1.6667   1.6667   1.6667   1.6667

nx = 5
ny = 3

References:

Axel Werner Richard Stockmar: Basic concepts of computer aided Iighting design - or how accurate are computer predicted photometrie values. In: CIE X005-1992: Proceedings of the CIE Seminar on Computer Programs for Light and Lighting, Commission Internationale de l'Eclairage (CIE), Vienna Austria, 1992, ISBN: 978 3 900734 41 1.

EN 12464-1:2021: Light and lighting - Lighting of work places - Part 1: Indoor work places. 2021.

DIN 5035-6:2006: Beleuchtung mit künstlichem Licht, Teil 6: Messung und Bewertung. 2006.