A model for sky-glow prediction

New suburbs, green house complexes, sports facilities and industrial areas: they all entail a significant amount of lighting. This lighting is necessary, but also gives annoyance. In the densily populated western part of the Netherlands, stars are almost invisible due to sky-glow. The effect of lighting on the night sky is therefore becoming ever more important in environmental effect reports.

Predicting

Until recently, it was difficult to predict the effect of the lighting of, say, a new industrial zone. An estimate could be made by looking at comparable situations. But this did not allow optimization of the plan with respect to different types of lighting: it is usually difficult to find even a single comparable situation.

Engineering firm Royal Haskoning asked VORtech to develop an application to predict sky-glow. The core of this application is a computational model that determines the effect of each lighting element. This model takes into account the weather conditions, the color of the light and whether the light is directed to the sky or to the ground. 

The results of the model are presented in a photomontage. Starting with a picture of the initial situation, the application computes the effect of the proposed lighting and modifies the picture accordingly. This takes into account the sensitivity of the camera for the shutter and diaphragm that has been used for the initial photo. The final picture gives a realistic prediction of the effect of the proposed lighting.

Multidisciplinairy

Awin Sewgobind from VORtech did most of the development of the application. Awin: 'I have become something of an expert in the field of digital camera's. You have to know a lot in order to reliably convert the lighting values that are predicted by the model to pixel values in the picture.' Apart from Awin, sky glow experts from Royal Haskoning and a professional photographer were also in the development team. Awin enjoyed the cooperation: 'An application like this is impossible to develop all by yourself. You just need too much knowledge about too many aspects. Working together in a multidisciplinairy team makes it possible to do something really special.'

The new application will be tested in a number of case studies. No doubt, further improvements will be made. But even as it is now, the new application gives much more grip in sky-glow than what was possible before.