Distributed lightning monitoring: an affordable proposal

Abstract

In theaters and the filmmaking industry, video streams, images, audio streams and scalar data are commonly used. In these fields, one of the most important magnitudes to be collected and controlled is the light intensity in different scene spots. So, it is extremely important to be able to deploy a network of light sensors which are usually integrated in a more general Wireless Multimedia Sensor Network (WMSN). If many light measurements have to be acquired, the simpler and cheaper the sensor, the more affordable the WMSN will be. In this paper we propose the use of a set of very cheap light sensors (photodiodes) and to spectrally and directionally correct their measurements using mathematical methods. A real testing of the proposed solution has been accomplished, obtaining quite accurate light measurements. Testing results are also presented throughout the paper.

Low cost multimedia sensor networks for obtaining lighting maps

“…The measurements obtained with the photodiode for different values of the sensor tilting angle θ, is compared with the results obtained using a mid-range commercial luxmeter [20] with a cost of about one hundred dollar. As the room is illuminated with non-A type lights, which have a different spectral behavior, the illuminance values have to be spectrally corrected with a factor σ, that in the case of the proposed photodiode takes the value σ = 0.112 [29]. On the other hand, as the sensor is receiving light from many directions and it is not optically-compensated, a directional correction factor ψ must also be included.…”

“…To obtain the above results it has been assumed that the sensor is exposed to a homogeneous 3D omnidirectional light. Now this assumption will be disregarded and the problem for the general lighting conditions described in [29] will be addressed. Using eqs.…”

“…Additionally, spectral compensation can also be obtained for this type of sensors as it is described in [29]. So, it is possible to deploy a sensor network, obtaining lighting measurements at different spots in a certain region by the spectral and directional correction of the electric current provided by low-cost sensors (photodiodes).…”

“…In previous work [29] the authors have proposed a different approach based on the use of very simple sensors. The measurement of light obtained from them is later corrected both spectrally and directionally by numerous methods without the need of additional hardware in each sensor.…”

“…The directional correction system proposed in [29] assumes a known distribution of light sources. As it will be shown in this paper, in many cases it is possible to generalize this correction of the light measurement to situations with indeterminate light sources without significantly altering the measurement error.…”