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:
Parameter | Description |
x and y | Contain the calculated grid coordinates. |
nx and ny | Are the resulting number of points in x and y dimension. These can be defined as input as well, to force a certain grid resolution. |
d and b | Define the dimension of the area A = d\times b. |
border | Defines a peripheral border zone which is not considered in the grid. |
mode | ‘std’ for default behavior resulting in an rounded odd or even number of points in each dimension, according to the current EN 12464 standard. ‘up’ for an rounded up number of points in each dimension, according to the previous EN 12464 standard. ‘odd’ to force an rounded up odd number of points in each dimension, as in the german standard DIN 5035-6. This has the advantage, that one can skip every second point for faster measurements while still having a fully functional grid. |
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 = Columns 1 through 8: 0.1623 0.4963 0.8302 1.1642 1.4981 1.8321 2.1660 2.5000 0.1623 0.4963 0.8302 1.1642 1.4981 1.8321 2.1660 2.5000 0.1623 0.4963 0.8302 1.1642 1.4981 1.8321 2.1660 2.5000 0.1623 0.4963 0.8302 1.1642 1.4981 1.8321 2.1660 2.5000 0.1623 0.4963 0.8302 1.1642 1.4981 1.8321 2.1660 2.5000 0.1623 0.4963 0.8302 1.1642 1.4981 1.8321 2.1660 2.5000 Columns 9 through 15: 2.8340 3.1679 3.5019 3.8358 4.1698 4.5037 4.8377 2.8340 3.1679 3.5019 3.8358 4.1698 4.5037 4.8377 2.8340 3.1679 3.5019 3.8358 4.1698 4.5037 4.8377 2.8340 3.1679 3.5019 3.8358 4.1698 4.5037 4.8377 2.8340 3.1679 3.5019 3.8358 4.1698 4.5037 4.8377 2.8340 3.1679 3.5019 3.8358 4.1698 4.5037 4.8377 y = Columns 1 through 8: 0.1623 0.1623 0.1623 0.1623 0.1623 0.1623 0.1623 0.1623 0.4974 0.4974 0.4974 0.4974 0.4974 0.4974 0.4974 0.4974 0.8325 0.8325 0.8325 0.8325 0.8325 0.8325 0.8325 0.8325 1.1675 1.1675 1.1675 1.1675 1.1675 1.1675 1.1675 1.1675 1.5026 1.5026 1.5026 1.5026 1.5026 1.5026 1.5026 1.5026 1.8377 1.8377 1.8377 1.8377 1.8377 1.8377 1.8377 1.8377 Columns 9 through 15: 0.1623 0.1623 0.1623 0.1623 0.1623 0.1623 0.1623 0.4974 0.4974 0.4974 0.4974 0.4974 0.4974 0.4974 0.8325 0.8325 0.8325 0.8325 0.8325 0.8325 0.8325 1.1675 1.1675 1.1675 1.1675 1.1675 1.1675 1.1675 1.5026 1.5026 1.5026 1.5026 1.5026 1.5026 1.5026 1.8377 1.8377 1.8377 1.8377 1.8377 1.8377 1.8377 nx = 15 ny = 6
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 = 26 ny = 13
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 = Columns 1 through 8: 0.1623 0.4963 0.8302 1.1642 1.4981 1.8321 2.1660 2.5000 0.1623 0.4963 0.8302 1.1642 1.4981 1.8321 2.1660 2.5000 0.1623 0.4963 0.8302 1.1642 1.4981 1.8321 2.1660 2.5000 0.1623 0.4963 0.8302 1.1642 1.4981 1.8321 2.1660 2.5000 0.1623 0.4963 0.8302 1.1642 1.4981 1.8321 2.1660 2.5000 0.1623 0.4963 0.8302 1.1642 1.4981 1.8321 2.1660 2.5000 0.1623 0.4963 0.8302 1.1642 1.4981 1.8321 2.1660 2.5000 Columns 9 through 15: 2.8340 3.1679 3.5019 3.8358 4.1698 4.5037 4.8377 2.8340 3.1679 3.5019 3.8358 4.1698 4.5037 4.8377 2.8340 3.1679 3.5019 3.8358 4.1698 4.5037 4.8377 2.8340 3.1679 3.5019 3.8358 4.1698 4.5037 4.8377 2.8340 3.1679 3.5019 3.8358 4.1698 4.5037 4.8377 2.8340 3.1679 3.5019 3.8358 4.1698 4.5037 4.8377 2.8340 3.1679 3.5019 3.8358 4.1698 4.5037 4.8377 y = Columns 1 through 8: 0.1429 0.1429 0.1429 0.1429 0.1429 0.1429 0.1429 0.1429 0.4286 0.4286 0.4286 0.4286 0.4286 0.4286 0.4286 0.4286 0.7143 0.7143 0.7143 0.7143 0.7143 0.7143 0.7143 0.7143 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.2857 1.2857 1.2857 1.2857 1.2857 1.2857 1.2857 1.2857 1.5714 1.5714 1.5714 1.5714 1.5714 1.5714 1.5714 1.5714 1.8571 1.8571 1.8571 1.8571 1.8571 1.8571 1.8571 1.8571 Columns 9 through 15: 0.1429 0.1429 0.1429 0.1429 0.1429 0.1429 0.1429 0.4286 0.4286 0.4286 0.4286 0.4286 0.4286 0.4286 0.7143 0.7143 0.7143 0.7143 0.7143 0.7143 0.7143 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.2857 1.2857 1.2857 1.2857 1.2857 1.2857 1.2857 1.5714 1.5714 1.5714 1.5714 1.5714 1.5714 1.5714 1.8571 1.8571 1.8571 1.8571 1.8571 1.8571 1.8571 nx = 15 ny = 7
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.