Most surround view systems use at least four wide angle cameras positioned around the exterior of the vehicle.

One camera is usually installed at the front near the grille. Another is positioned at the rear, commonly close to the license plate or tailgate handle. The remaining two cameras are normally mounted underneath the left and right side mirrors.

Each camera captures a very wide field of view. Their coverage overlaps, allowing the system to see most of the ground immediately surrounding the vehicle.

The cameras themselves are relatively small, which is why many drivers may never notice them unless they look closely underneath the mirrors or around the front and rear bodywork.

Images from wide angle cameras naturally contain significant visual distortion. Straight lines near the edges of the image can appear curved because of the wide field of view.

The vehicle computer first corrects this distortion. It then applies perspective correction so each camera image can be represented as though it were being viewed from above rather than from the side of the car.

Calibration data tells the system exactly where every camera sits in relation to the vehicle. This allows the computer to align the images accurately.

Areas captured by more than one camera are blended together to reduce visible seams. Once the four views have been processed, the system creates one continuous image around the vehicle.

One of the cleverest parts of the system is the vehicle shown in the middle of the display.

The cameras cannot actually see through the body of the car or photograph its roof from above. Instead, software places a digital representation of the vehicle in the center of the combined camera image.

This graphic covers the area occupied by the actual car and completes the illusion that the driver is looking down from a camera positioned above the roof.

Some newer systems can also change the viewing angle digitally, creating three dimensional perspectives that appear to rotate around the car. These views are still generated from the surrounding cameras and computer processing.

A surround view system is extremely useful during parking, but the image should not be treated as a perfect representation of the surroundings.

The system is primarily designed to reconstruct the ground around the vehicle. Tall objects can appear stretched, curved or separated where images from different cameras are joined.

Distance can also be difficult to judge precisely because the software changes perspective to create the top view. An obstacle may therefore appear slightly closer or farther away than expected.

Mud, rain, snow or dirt covering one camera can also create blurry areas or interfere with image stitching.

Drivers should use the 360 degree camera together with mirrors, parking sensors and direct observation rather than relying entirely on the display.

The technology works because several simple camera views are transformed into one sophisticated digital image in real time. What appears to be a camera floating above the roof is actually a carefully calculated virtual perspective designed to make parking and low speed maneuvering easier.