Range information is extracted using proprietary algorithms implemented in hardware in the sensor.
Internally, the sensor utilises a sequence of frames to do this, running at a very high internal frame rate. An ambient light intensity image can be captured as part of the sequence — machine vision with depth.
Table of Contents: TOF range-imaging cameras
It is also possible to utilise the laser illumination as an intensity flash to capture the intensity image with IR illumination — so called active IR. The use of short but intense pulses of light ensure that the system is able to operate in even high levels of ambient light outdoor applications are possible.
In very bright situations, it may be useful to incorporate a bandpass filter centred around nm. Very busy, or cluttered scenes, especially with reflective objects can result in multipath returns where the emitted pulse is reflected multiple times from multiple objects before detection at the sensor. Multipath is undesirable in a time-of-flight measurement, adding uncertainty to the measured range.
Each and every pixel on the image sensor is used to capture both range 3D and intensity information.
TOF Range-Imaging Cameras
However, with only a finite area behind the objective lens, pixels on high resolution sensors are small for example, each of the pixels on the 1. This is generally not a concern in the intensity image, as exposure time is much longer and the intensity of ambient light incident on the pixel is much higher.
Frame accumulation in the sensor hardware is a user controlled feature that allows multiple samples of the range image to be captured, and accumulated together to improve the quality of the range measurement.
The number of frames used is user programmable, with the effect that a higher number of accumulations results in an improved range measurement, with a small impact on output frame rate. By capturing, reconstructing, or simulating light transport at extreme temporal resolutions, researchers have proposed novel techniques to show movies of light in motion, see around corners, detect objects in highly-scattering media, or infer material properties from a distance, to name a few.
- Special Issue "Time-of-Flight Range-Imaging Cameras".
- How to Prepare for Life’s Unknown.
- Pulse Based Time-of-Flight Range Sensing.
- The Way Of Peace;
- A reconfigurable × image sensor controller that is compatible for depth measurement.
- Explained: Time of Flight Cameras (TOF)!