Design Challenges and Technology Solutions for Surround View DA

Surround View DA systems capture the area surrounding the vehicle by way of four high-resolution video cameras, usually installed behind the front grid and incorporated in the back door and two side mirrors. The body shapes and sizes of different vehicles dictate the camera installation points and  each vehicle requires a unique setup of the system. The cameras are furnished with lenses with an extreme wide-angle Field of View (FOV > 180o) which cause the fish-eye distortions in output video. Furthermore, each camera captures the surroundings from the perspective defined by its installation point. That perspective must be transformed into perspectives suitable for selected views, i.e. the bird's eye view perspective.
Xylon Automotive Four-Camera Surround View Driver Assistance System
Lens and Perspective Image Corrections
The Surround View system must remove the lens distortions and correct the perspectives of four high-resolution input video streams, and then stitch the corrected video images in a single display of the vehicle’s surroundings. Correct image stitching is very challenging due to overlapping of the scenes captured by the cameras as a result of the extreme wide-angle FOV lenses.

The amount of video data, which must be processed in real-time, is big and requires dedicated DDR2 or DDR3 SDRAM memory devices. The interface between the Surround View DA system’s processing unit and the memory must assure data throughputs that reach 1GByte/sec in systems with 1280x800 resolution and 30fps camera imagers.

The Surround View DA software must be easy to use and capable to solve the following challenges:
  • quick system adoptions to different car types; body shapes dictate camera installation points and require unique system setup
  • static and dynamic system calibrations
  • easy exploration of different viewing options
  • use of different camera sensors, lenses, camera interfaces, interfacing with other ECUs, HMI control, ...

Screenshot from Xylon's Surround View Calibration Software - The Preview Feature

The Surround View DA system must overcome camera control and interfacing challenges. The system’s cameras must be synchronized to avoid the appearance of image tearing and other unwanted display artifacts. The cameras may be exposed to extremely different lighting conditions, for example two cameras may be in direct sunlight and the other two may be in a shadow, and such lighting conditions must be properly equalized. New cameras and interfaces are developed quickly and Surround View DA systems must be flexible to keep up with the pace of emerging camera solutions.

High computing performances, low-power, high EMI resistance, and other stringent requirements typical for automotive applications can be fulfilled by using a limited number of silicon solutions. 

Some general purpose embedded processors offer excellent computing performances boosted by on-chip graphics co-processors and a good choice of communication and other peripherals.

These silicon products are somewhat limited in camera and other sensor's fusion options and require supporting silicon devices for the connection of multiple cameras. Serial DSP products suffer from the same connectivity issues and may have limited performances.

While the ASSP silicon products are traditionally a good match for the most common application requirements, they enable product differentiation at the software level only. New and fast changing computational algorithms, camera sensors and interfaces, memories and display types, new application requirements, such as an additional (fifth) camera, interfacing to other automotive systems, etc., may cause connectivity or even performance limitations.

Xylon offers complete FPGA based solution for second generation Surround View Systems!

Read More:

- Four-Camera Surround View DA
- Xylon Solutions for Xilinx FPGA Based Surround View DA
- Overview of Xylon solutions for the Surround View DA

Learn more about Xylon's solutions for the automotive market:

- Pedestrian Detection
- Lane Departure Warning
- Infotainment Companion Chip
- Performance Display
- Rear-View Camera
- Automotive Instrument Cluster
- Rear-Seats Entertainment

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