The complexity of optical components in traffic control systems illustrated

By Vision Light Tech

Traffic control is one of the most current issues in the infrastructure industry. Two important subjects in this industry are Rail Inspection and License Plate Recognition. The current developments in rail inspection outline the complexity of these subjects. The rails of the Dutch Railways are still inspected manually. Inspectors literally check the railway yards for wear and other defects inch by inch. This is particularly done at exchange points. Nowadays this method sounds outdated; still it is the most reliable method. There is only one single reason to it: the alternative, Automatic Camera Inspection, is extremely complex. Only the most experienced and technically grounded lighting professionals are able to develop a system that equals the quality of manual inspection. These professionals seem to be extremely rare. 

This does not automatically mean that they do not exist at all. Vision Light Tech (NL) is momentarily working on the most complex part of the camera inspection system: the illumination. A constant amount of light is needed for automatic inspection. Most preferably it should resemble the natural light on a sunny day. Illumination does not revolve around light on its own. It also encompasses the use of filters & lenses. Only an optimised combination of these three elements enables a high and constant light quality, which is necessary to reach similar or even better results.

The holy trinity: light, lens & filter
Attaching a strong as possible lamp to the camera is not sufficient. The amount of light is part of the problem, or rather, part of the solution. The challenge is to achieve a high as possible contrast. The higher the contrast, the clearer the image is. This is best illustrated by means of another example: License Plate Recognition.

There are several organisations with diverse reasons for checking out vehicles. The government does not just check speed, but is also interested in country of origin, truck loads and other information that can be traced by codes on vehicles. Naturally these codes and license plates come in all sorts of colours and shapes. Recognition is also hampered by influences such as speed, weather conditions and pollution. Moreover it is not in the driver’s best interest to distract him with sudden light flashes. Therefore the control devices require certain invisibility. In short: there are many factors that need to be considered.

The two remaining questions are:
• Which combination of light, lens & filter offers the highest contrast for every situation imaginable?
• Which wavelength is required to enable recognition of every possible license plate or code on the vehicle?

Raising these issues is crucial when determining the maximum amount of contrast necessary for creating an optimized inspection system. Subsequently tests can be done to determine whether the correct solution is chosen. VLT already know the answers in advance. In the course of years they have fitted many automated control systems with illumination. Vision Light Tech is able to offer their customers the possibility to test the systems before purchasing them.
 
Many organisations disregard the combination of light, lens & filter and concentrate only on illumination.

A lens filters the correct wavelength
Both Paul van der Velde (general manager) and Marco de Roder (sales engineer) of VLT gained their knowledge and experience in another sector. Under the name Vision Light Tech they offer, over more than 10 years, light solutions for Automated Quality Control of production processes i.e. Machine Vision.

Through the years Vision Light Tech noticed that many organisations disregard the combination of light, filter & lens and concentrate only on illumination. It was thought that logical thinking could solve the issue. This is not as surprising as it might seem.

An example:
Last year VLT was approached by a company that used camera systems for inspecting steel profiles. Sunlight distorted the image, which resulted in an inconsequent control quality. Their solution to the problem seemed a logical one. The camera was shaded from direct sunlight and the light density enhanced. Vision Ligh Tech created a more simple and efficient solution for them. They discovered which wavelength was required to inspect the profiles to an optimum. So they installed a filter that transmitted the required wavelength and averted the sunlight.
This example reflects a way of thinking; the problem itself is tackled instead of aiming at existing techniques. Only then a solution will be simple and efficient. This gives quality for value.

A request for ‘light’ can therefore never be answered with a standard solution.


Vehicle recognition relatively simple

The influence of illumination is commonly known. Everyone can see the difference between a professional photograph and a picture taken by an amateur. Even a change in atmosphere can be sensed when lights are dimmed or when the sun comes out. The consequences of good illumination reach beyond the change in emotion.

Vision Light Tech experienced that the definition of every problem is different and requires constant investigation. This does not apply to vehicle recognition.

In Automated Quality Control many problems can be defined, but vehicle recognition has only few. During general production processes there are many variables to consider, such as size, shape, material etc. While with vehicles the circumstances never show such diversity.
A current subject in the light industry seems to be finding the right people. At this moment much is being invested in European infrastructure. Vehicle recognition is an important issue. By managing this vehicle recognition project correctly Vision Light Tech will be able to integrate all the required information into one efficient system. Concentrating on the optical elements of the system is crucial.

Vision Light Tech: creating optical solutions
Vision Light Tech supplies a broad range of solutions in light, lenses & filters from their office in Uden. The people behind the Vision Light Tech company are Paul van der Velde and Marco de Roder. Both are renowned for their speciality in this niche market. The organisation distinguishes itself from others by a problem focussed approach. Vision Light Tech has many years of experience in the automated quality control of production processes and is recently discovered by the vehicle recognition sector. Paul and Marco both believe they are unique in combining their products and knowledge with in-depth problem solving methods. Vision Light Tech already developed light solutions for the industrial machine vision industry and the microscope market. The company is also able to deliver standard products. Vision Light Tech is supported by a European network of OEM’s, vision system integrators, distributors and end users. 

Vision Light Tech:
• Is the first and leading photonics-specialist in imaging applications;
• Works with market leading companies around the globe;
• Gives brand independent advise;
• Offers guaranteed solutions of the best quality;
• Is member of the AIA and EMVA (machine vision sector organisations).

Contact information:
Vision Light Tech
T: +31 413 260067, F: +31 413 260938, W: www.visionlighttech.com
Press contact: Paul van der Velde, E: pvdv@vlt.nl  – not for publication
Sales contact: Marco de Roder, E: info@vlt.nl