Archive Newsletter 2016 ()

Fish-Eye Lenses

Nowadays almost unthinkable: parking without parking assistance

In addition to driving pleasure and comfort, above all the safety plays a decisive role in modern vehicles. Therefore, the automobile manufacturers have for years increasingly focused on various driver assistance systems that can intervene in a variety of everyday and emergency situations. More and more systems use cameras to generate and process a complete picture of the vehicle surroundings. The recordings used for this purpose come from cameras with different lenses. Based on this information, various actions such as a braking maneuver, can be introduced. For the enormous testing and validation effort of camera-based driver assistance systems, the open integration and test platform CarMaker can be used, which allows the camera-based systems to be tested and validated in the virtual test-driving throughout the entire development process (MIL / SIL / HIL).

An application example is the Topview function in the display of the vehicle. Here, a panoramic view is generated by the fusion of data from multiple cameras with different angles and lenses. The images obtained are for instance used for a parking assistant. One lens used in this scenario is the so-called fish-eye lens with a point of view inspired by the sight of a fish through the water surface. This type of lens functions in a way that the picture shown is represented curved apart from the center of the image. The advantage of this method for use in driver assistance systems is the large angle of view that is obtained thereby. At the same time, camera-induced image errors are possible. First of all, there are distortions that represent the real image distortedly. Secondly, a common source of error is the so-called vignetting, i.e. the increasing shadow towards the margins. Taking these real properties of the sensor-based systems into account already in the virtual testing and modeling is a major challenge. This is made possible by IPGMovie. The 3D animation supports the simulation of all four marketable fish-eye lens types (angle preserving, divided linear, equal area, and orthographical) in real time. The view of the lenses can be configured freely and adapted to the needs of the respective driver assistance system to be tested in an angular range from 90 to 250 degrees.

Classic video-HIL setups of camera, control unit, and a monitor or a screen set up opposite reach their limits particularly for this type of lens. Coverage angles of more than 180° cannot be covered by flat monitor surfaces. Arrangements of curved screens and corresponding projectors mean high implementation effort. For these and many other (special) cases (e.g. B. stereo camera-based ACC), IPG Automotive is working on a hardware that feeds the video data from IPGMovie directly into the electrical interface between the camera and control unit.

The possibility of testing of the sensor data fusion algorithms in CarMaker long before the production stage makes an integration into the overall vehicle easier and faster. In addition to a high level of maturity, this leads to advantages over costly validation tests in real prototypes. With CarMaker, it is also possible to combine different data from sensors and cameras. Therefore, testing and validation of more complex driver assistance systems is possible in order to ensure maximum safety on the road.