Geometric calibration models of infrared cameras and scanners for photogrammetric and remote sensing applications

Büyüksallh G.

Article | 2003 | Optical Engineering42 ( 7 ) , pp.1923 - 1934

The paper is concerned with the geometric calibration of infrared imaging systems with a view to use them in both photogrammetry and remote sensing applications, From the geometric point of view, three quite different types of infrared imagers can be distinguished: 1. the pyroelectric vidicon camera; 2. the CCD camera with 2-D areal array of solid-state detectors; and 3. the thermal video frame scanner (TVFS). These operate in different parts of the infrared spectrum. The special optical and detector technologies used in these different devices are first reviewed. On this basis, a special target plate is constructed with its own int . . .ernal radiation source that allows all of these devices to be calibrated geometrically. The actual experimental and calibration procedures are described, as is the method used for the automated measurement of all the targets using image matching techniques. The subsequent data processing and analysis are then outlined. The results obtained from the successful calibration of a representative sample of CCD cameras and thermal video frame scanners are presented and discussed in detail. They provide much new and accurate information on the geometric characteristics of these imagers that can be used in military, medical, industrial, and environmental applications. © 2003 Society of Photo-Optical Instrumentation Engineers Daha fazlası Daha az

Practical experiences with automatic aerial triangulation using different software packages

Büyüksalih G. | Zhang L.I.

Article | 2003 | Photogrammetric Record18 ( 102 ) , pp.131 - 155

Digital photogrammetry and softcopy workstations have added a new dimension to aerial triangulation, and some of the previously manual procedures are now available in automated form. Also, commercial software packages for automatic aerial triangulation came on to the market in the last decade. In this study, the results of automatic aerial triangulation using four triangulation software packages, Z/I Imaging's MATCH-AT (ISMAT) and ISAT, LH Systems' MST and VirtuoZo AAT, are presented. For the comparison of the results of the tie point extraction and the bundle block adjustment for triangulation, a sub-block from the Uster block in S . . .witzerland was selected and used. Differences between these software packages are discussed with respect to their functionality and performance in detail. The achieved standard deviation of image coordinates varies between 0-2 and 0-5 pixel for the systems tested. The more signalised control points and check points to be used, the better the ? 0 estimate which could be expected. The average number of extracted tie points varied from system to system with respect to the matching method and the resolution of the images used in the programs. The digital aerial triangulation of the Uster sub-block was faster than analytical triangulation and the elapsed time for triangulation of one image using different systems varies between about 0-5 and 6 min. Nevertheless, results also show that automated aerial triangulation is still prone to error in all systems. Image matching produces many blunders, which can only be handled efficiently by using a sophisticated blunder detection procedure, as is available with robust estimation. This is not the case for all the systems tested, however. There still remains a lot to be done in terms of development (improvement of matching, for example, by integrating robust estimation for error detection at an early stage, implementation of online triangulation, better internal quality control procedures, more transparent and simple user interfaces and more useful information for the user with better software manuals). However, it was shown that automatic aerial triangulation provides higher redundancy and reliability of results and much more economical photogrammetric practice than ever before Daha fazlası Daha az

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