Influence of the calculation grid density to the selected photometric parameters for road lighting

Calculation and measurement of performance parameters of public lighting are performed in a grid of points defined by the CIE publication 140 and European standard EN 13201-3. Calculation grid defined in these documents was created at a time of low powerful computers and less precise measuring technology. Distance between two adjacent calculating points may be a 3 m, depending on the geometry of the road. This arrangement is sparse view of the fact that the present used computer can cope with much more denser grid in a short time and the measurement can be performed by the luminance analyzers. Between the results of the calculation with different grid densities of calculation points may be significant differences. This fact may influence the new optical systems and some LED luminaires which as found by measurement may contain various local extremes in the light intensity distribution curve. In calculating of performance parameters of public lighting and given the current used grid density these extremes may fall between calculation points and thus may not be included in the calculation. The solution is to propose a new density of calculation points which would be designed with respect to current possibilities of computer and measuring technology. The paper deals with the influence of grid density to the resulting photometric parameters of public lighting. In computing software will be used calculation grid of points according to EN 13201-3 and calculation grid with densification of calculation points in order to capture given local extremes to the resulting parameters The results will be used in the preparation of future revisions of normative documents, which provide a method for determining points of calculation and measurement grid.