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Friday, July 23, 2010

PowerPoint Presentation On 3D Time Of Flight Camera

 PPT On 3D Time Of Flight Camera


3D Time Of Flight Camera Presentation Transcript:
1. The 3D-Time-of-Flight camera
(ToF) is a new concept for image and video capturing - captures not only two, but three dimensions in one step by measuring the distance from each pixel of the camera chip to the object. This way a large number of coordinates is determined for each exposure – a so called frame. The systems cover ranges of a few meters up to about 60 m. The distance resolution is about 1 cm. The biggest advantage of the cameras may be that they provide up to 100 images per second.

2. Illumination unit:
It illuminates the scene. Normally LEDs and Laser diodes are feasible. The illumination normally uses infrared light to make the illumination unobtrusive. Image sensor: This is the heart of the TOF camera. Each pixel measures the time the light has taken to travel from the illumination unit to the object and back.. Optics: A lens gathers the reflected light and images the environment onto the image sensor. An optical band pass filter only passes the light with the same wavelength as the illumination unit. This helps suppress background light.

3. Driver electronics:
Both the illumination unit and the image sensor have to be controlled by high speed signals. These signals have to be very accurate to obtain a high resolution. Computation/Interface: The distance is calculated directly in the camera. To obtain good performance, some calibration data is also used. The camera then provides a distance image over a USB or Ethernet interface.

4. A Time of flight camera (TOFcamera) is a camera system that creates distance data with help of the following principle : Time of Flight Principle(TOF) describes a variety of methods that measure the time that it takes for an object, particle or acoustic, electromagnetic or other wave to travel a distance through a medium. This measurement can be used for a time standard, as a way to measure velocity or path length through a given medium, or as a way to learn about the particle or medium . The traveling object may be detected directly or indirectly

5. The 3D Time-Of-Flight (ToF) camera, simultaneously delivers gray-level images and 3D information of the scene. Illumination source is in the form of matrix of LEDs. On the basis of reflected ray: Distance Image (D(i, j)) is computed based on the phase shift between the emitted and reflected signals Amplitude Image (A(i, j)) is estimated based on the amplitude of the reflected signal at every pixel location

6. A ToF camera actively illuminates a scene with an incoherent light signal. The signal is modulated by a cosine-shaped signal of frequency f. Usually, the emitted light is part of the non-visible area of the spectrum in the near infrared spectral range (780 nm). Traveling with the constant speed of light in the surrounding medium, the light signal is reflected by the surface of the patient. By estimating the phase-shift f (in rad) between both, the emitted and reflected light signal, the distance D(i,j) can be computed as follows: d=1/2(n*wavelength + phase)

7. the amplitude image A(i, j) is estimated based on the amplitude of the reflected signal at every pixel location. For emitted ray: D (t0) = Acos wt(0). For reflected ray: d(t) = k + a cos (wt + ). Use of depth information in addition to amplitude may be a key factor for finding workable solutions to a number of applications of interest,e.g., face detection, video surveillance etc. TOF-can generate a depth map of what is being seen through the camera at a short range, and use this data to approximate a 3d representation of what is being seen.? These can be effective for detection of hand gestures due to their short range capabilities.

8. Pulsed light source with digital time counters These devices produce depth values for each pixel on every frame. Typical image sizes are 128 x 128 pixels. RF-modulated light sources with phase detectors Photonic Mixer Devices (PMD) and the Swiss Ranger are eg. These are compact & short range devices. Range gated imagers This is the most promising technology. The phase detector is the gate or shutter in the camera. The gate allows collection of portions and of the received light pulse. The Z-cam and Canesta 3D cameras.

9. Simplicity Efficient Distance Algorithm Speed

10. For more please refer our PPT. Thanks.

Related Project Report:

3D Time Of Flight Camera

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