Automotive ADAS has numerous features, one of the features that is picking pace in mass market vehicles is surround view. Surround view system uses cameras placed across the body of the car to provide a clear image of surroundings which assist with either manual parking or automated parking.
Surround view system is the latest must have feature for new cars, it not only makes parking easier for the user but also helps in automated parking with extended features like object detection. Surround view systems can be designed with help of two types of sensors- one being radar and other camera. Camera is the most preferred since it offers visuals of the surroundings on the dashboard (IVI screen). On most of the cars the surround view system is activated as soon as the user engages reverse. The surround view system offers various views of the surroundings such as front view, side view, rear view and also birds eye view.
A camera-based surround view system can be achieved with 2 cameras or 4 and more cameras depending on the extended features. A surround view system typical has following sub systems:
1. Camera unit
2. Image Processing
3. Display system
1. Camera unit
Usually depending on the size of the vehicle, cars are equipped with more than 2 wide angle cameras which are placed strategically across the body panel such that there is no blind spot and all the area is covered.
2. Image processing
Wide angle cameras coupled with dedicated image processing algorithms are a must have. These include specific algorithms like fish eye distortion, image stitching and correction. In some cases, auto white balance and auto exposure are also used depending on the overall cost of the system, this helps in getting the best view possible at all the time.
3. Display system
Usually IVI screen- LCD doubles up as a surround view system, this is coupled with audio feedback which utilizes car speakers. The display system allows users to choose the type of view as well as view of each camera for finer details.
Depending on the final features surround view systems are classified as 2-D and 3-D
2-D surround view- As the name suggests this system provides a 2D mapping of surroundings with a bird’s eye view. Feed from the camera is stitched to provide a fixed number of views on a flat surface.
3-D surround view- The vehicle surroundings are shown in a life-like 3-D picturization in this system with option to choose a wide variety of views available. Generally, users will have an option to pinch & zoom and also rotate the screen to view even minute objects in the surrounding area.
Camera calibration for surround view
As with all camera applications in automotive use, surround view camera systems need dedicated calibration. Calibration takes care of adverse effects on the system such as tire pressure, vehicle load etc.
