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Comparison by simulation of different approaches to the urban traffic control

Prikryl J., Tichy T., Belinova Z., Kapitan J.

Archives of Transport System Telematics

2012

Vol. 5, iss. 4

26-30

As the urban traffic volumes reach their daily peak values, the surface traffic in modern cities suffers from frequent breakdowns and traffic jams. One of possibilities that could mitigate the problem is the deployment of smarter automatic systems of urban traffic control. Our paper demonstrates a development version of such a system. The system is based on adaptive feedback control approach. It makes use of filtering techniques to account for measurement imperfections and implements the rolling horizon method for optimal signal control. We compare the performance of the proposed system with two typical control approaches - pre-timed (or fixed) control, and traffic actuated (or dynamic) control. Different scenarios will be compared, including rapid changes in traffic volumes and reactions to incidents. The comparison is carried out using our demonstrator tool, based on TSS Aimsun micro-simulator. In order to keep the calibrated simulation as close to reality as possible, in the comparison runs we use real dense input volume measurements and simulate also the behavior of intersection controllers.

The constant radiance term

Neumann L., Neumann A., Prikryl J., Purgathofer W.

Machine Graphics and Vision

1998

Vol. 7, No. 3

535-549

This paper describes a fundamential improvement for all rendering methods that evaluate the rendering equation in any complexity. The "constant Radiance Term" accelerates the computation of multiple interreflections in arbitrary non-diffuse environments. It is an extension of the constant radiosity step untroduced ealiner for solving radiosity problems and does not require geometrical nor visibility information. A constant radiance portion is extracted from the solution in every surface point and every direction. The residuum problem can be solved faster or with reduced variance by all known methods that consider non-diffuse light interreflections, like different versions of distribution ray tracing, deterministic and stochastic radiosity methods, and hybrid solutions. The constant radiance value is chosen in such a way that the total self-emitted power of the residuum problem is zero so that after the extraction of the constant part there are places with positive self-emittance and places with positive self-emittance and places with negative self emittance. The achieved acceleration can be significant for environments with many bright coloured surfaces. Using a decomposition into separate positive and negative problems it is possible to apply the technique even when using turnkey rendering software.