3D ToF Technology
3D camera gives us the distance image, i.e. the image shows the distance to the scene object in each pixel of the picture.
All the images are translated in real time.
Tree Main 3D sensors technologies
There are three main optic technologies of 3D cameras: Stereovision, Structured light and Time-of-Flight (ToF).
Stereo-cameras use the binocular principle. Estimation of distances is implemented by juxtaposition of shots made from two different, but close positions (triangulation method). The juxtaposition of shots is implemented on the computing unit with the help of special algorithm. This method requires the presence of textures on the scene objects.
3D cameras based on structured light use the special image projection on the scene and shooting this image with the high resolution camera. The distance is calculated by algorithmic processing. Such 3D cameras do not require the texture on the scene objects, but still need the computing unit.
Time-of-Flight 3D cameras estimate the distance by measuring the phase delay of modulated light. Technology does not require additional computer processing, that is why is the fastest and reliable method of getting the distance map.
The main idea of Time-of-Flight technology is in measuring the time of light signal return. This measurement is implemented separately in each pixel of photosensitive matrix. Two charge storages are switched synchronous and in-phase with pulses of light signal are used for this delay measurement. Simple to estimate the phase delay of return light signal and then the distance by ratio of charges in the storages.
3D ToF cameras suffer from background light, because is necessary to register only own modulated illumination. Suppression of background light becomes a cornerstone in the design of ToF-sensors. The microelectronic circuit realizing this suppression is the necessary node in each construction, and it’s implementation is defined of the 3D image quality. Our company uses only high-quality 3D ToF microsensors from the companies PMD and Texas Instruments.