KEYWORDS: Image processing, Time of flight cameras, Clocks, Algorithm development, Cameras, Field programmable gate arrays, Modulation, Stereo vision systems, Signal processing, Real time image processing
During the last years, Time-of-Flight sensors achieved a significant impact onto research fields in machine vision. In
comparison to stereo vision system and laser range scanners they combine the advantages of active sensors providing
accurate distance measurements and camera-based systems recording a 2D matrix at a high frame rate. Moreover low
cost 3D imaging has the potential to open a wide field of additional applications and solutions in markets like consumer
electronics, multimedia, digital photography, robotics and medical technologies. This paper focuses on the currently
implemented 4-phase-shift algorithm in this type of sensors. The most time critical operation of the phase-shift algorithm
is the arctangent function. In this paper a novel hardware implementation of the arctangent function using a
reconfigurable processor system is presented and benchmarked against the state-of-the-art CORDIC arctangent
algorithm. Experimental results show that the proposed algorithm is well suited for real-time processing of the range
images of TOF cameras.
In this paper we consider a new way for automated camera calibration and specification. The proposed setup is optimized
for working with uncooled long wave infrared (thermal) cameras, while the concept itself is not restricted to those cameras.
Every component of the setup like black body source, climate chamber, remote power switch, and the camera itself is
connected to a network via Ethernet and a Windows XP workstation is controlling all components by the use of the
TCL - script language. Beside the job of communicating with the components the script tool is also capable to run Matlab
code via the matlab kernel. Data exchange during the measurement is possible and offers a variety of different advantages
from drastically reduction of the amount of data to enormous speedup of the measuring procedure due to data analysis
during measurement. A parameter based software framework is presented to create generic test cases, where modification
to the test scenario does not require any programming skills. In the second part of the paper the measurement results of a
self developed GigE-Vision thermal camera are presented and correction algorithms, providing high quality image output,
are shown. These algorithms are fully implemented in the FPGA of the camera to provide real time processing while
maintaining GigE-Vision as standard transmission protocol as an interface to arbitrary software tools. Artefacts taken into
account are spatial noise, defective pixel and offset drift due to self heating after power on.
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