Motion Interpretation for In-Car Vision Systems

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Requirements for Motion Estimation in Image Sequences for Traffic Applications

In traffic applications research in devices that can increase the safety and comfort of vehicles is an important topic. In this paper a digital rear-view mirror is presented that helps the driver to analyse situations on the road behind him. From the observations from a camera the optical motion in the image plane can be estimated. Based on this motion estimation the real-world motion of the vehicles behind our car is interpreted. The motion interpretation problem is very sensitive for errors introduced in the motion estimation. This paper describes a method that shows how accurate the motion estimation must be to enable the required accuracy of the motion interpretation. This will be done by means of simulation experiments for characteristic situations (vehicle approaching, retreating or shifting lane). 1. Introduction 1.1. Moving vehicles around you Far over a 90% of road traffic accidents are attributable to human error. To increase the safety on the road, research is done in a di..

The role of wind in the dispersal of floating seeds in slow flowing or stagnant water bodies

Question What is the role of wind in the dispersal of waterborne seeds in slow-flowing and stagnant water bodies at different temporal and spatial scales? (i) Is there a direct effect of wind on seed dispersal speed and distance? (ii) Are prevailing wind conditions reflected in the seed deposition patterns during a year? (iii) What are the long-term (multiple year) effects of prevailing wind conditions on the pattern and composition of shoreline seed banks? Location The Westbroekse Zodden (52˚10N; 5˚07E) and De Weerribben (52°46N; 5°55E) fen reserves in The Netherlands. Methods Real-time seed movement tracking experiments were conducted at different wind speeds. Additionally, we performed a seed trap experiment using artificial grass mats and carried out seed bank analyses using a seedling emergence test. Results Wind speed and direction strongly determined the dispersal process and the resulting deposition patterns of floating seeds in shallow lakes or ponds. Wind speed directly influenced dispersal speed and distance. Increasing wind speed increased dispersal speed but decreased dispersal distance. Over multiple seasons, more seeds were deposited at downwind shorelines than at upwind shorelines, showing that wind-driven hydrochory resulted in directional transport according to the prevailing wind direction. The species composition of deposited seeds was also affected, with proportionally more water-dispersed seeds being deposited at down-wind shorelines. These effects of wind speed and directionality will have consequences for the colonization of riparian zones in lentic systems and, therefore, also influence management and restoration. In the long term, local seed banks in riparian zones reflected the prevailing wind conditions poorly, showing that additional processes, such as differential germination and predation, also play important roles at longer time scales. Conclusions Wind plays an important role in the dispersal of waterborne seeds in lentic systems and (prevailing) wind speed and direction are reflected in seed dispersal trajectories and deposition patterns.

A resource-efficient and highly flexible procedure for a three-component synthesis of 2-imidazolines

(Chemical Equation Presented) A multicomponent reaction between α-acidic isonitriles, primary amines, and carbonyl compounds was studied using 14 different solvents. Depending on the isocyanide that was used, optimal yields for the three-component synthesis of 2H-2-imidazolines were observed in different solvents. The solvents could be used as purchased, and in situ preformation of the imine was not required. By selecting the appropriate solvent, it was possible to considerably expand the range of compatible isocyanides toward less α-acidic isocyanides. Further process simplification was achieved by performing the reaction at higher concentrations and avoiding purification by column chromatography, resulting in a fast, easy to perform, and resource-efficient protocol for this three-component reaction. © 2007 American Chemical Society