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IoT imaging system for color temperature and luminance - MAXLUM

Research contract funded by UEFISCDI type PN-III-P2-2.1-CI-2018-1490, No. 256CI / 2018

Co-financing: SC ELECTROMAX SRL Petroșani

Project duration: between September 3, 2018 and December 14, 2018.

Report to December 15, 2019

Project team:

  • Phd. Cătălin Daniel Gălățanu, professor at "Gheorghe Asachi" Technical University of Iaşi
  • Phd. Cristian Gyozo Haba, professor at "Gheorghe Asachi" Technical University of Iaşi
  • Phd. Daniel Petrișor, lecturer at "Gheorghe Asachi" Technical University of Iaşi
  • Phd. Iulian Gherasim, lecturer at "Gheorghe Asachi" Technical University of Iaşi

Results:

  • Number of patent applications filed: 1, at November 2019

Published papers:

  1. Gălățanu, Cătălin-Daniel; Petrișor, Daniel; Breniuc, Liviu; Imaging Measurements for Public Lighting Predictive Maintenance, 11th international symposium on advanced topics in electrical engineering (ATEE), WOS:000475904500067 , 2019
  2. Breniuc, Liviu; Haba, Cristian-Gyozo; Gălățanu, Cătălin-Daniel; et al., Correlated Color Temperature Measuring and Adjustment System, 11th International Symposium on Advanced Topics in Electrical Engineering (ATEE),WOS:000475904500083, 2019

The principle of the method of measuring color temperature and luminance

Canon EOS 4000D DSLR Calibrated Digital Camera, 18.0 MP for measuring Color Temperature (K) and Luminance (cd/m2), which measures the luminance field and color temperature of light sources. The camera is calibrated individually, according to the optics (lens) and the measurements are made based on the particular optoelectronic characteristic of the sensor, and not the range of sensors. Vigneting errors are determined and compensated.

The camera can be used to measure luminance in street lighting, according to EN 13201, when finalizing and accepting the works procedure for lighting systems.

For the maintenance of the lighting systems, according to Fig.1, it is possible to obtain the luminance distributions on the road line, according to Fig.2:

Fig. 1. Lighting system on Octav Băncilă Street, Iași
Fig. 2.  Map of luminaires for lighting system on Octav Băncilă Street, Iași

For luminaires, regardless of whether they are indoor or outdoor, you can obtain the distribution of luminances for very high values, with an example in Fig.3, based on which one can develop preventive maintenance strategies, non-existent in current practice.

Fig. 3. Luminance distribution for a LED street light fixture

The program interface is intuitive (Fig.4) and does not require programming knowledge (MATLAB). A space of 700 MB is required for installation and no licenses or other resident programs are required.

Fig. 4. Print Screen with Software interface

For specialized correlated color temperature (CCT) measurements, the RGB to XYZ conversion matrix can be calculated for various types of image sensors.

The main results:

  • Calibration of a digital camera to measure color temperature (K) and luminance (cd/m2).
  • Dedicated software for imaging processing of color temperature (K) and luminance (cd/m2).