Proceedings of the Symposium on Progress in Data Processing and Analysis

Bibliographic data

Monograph

Persistent identifier:: 856470848

Title:: Proceedings of the Symposium on Progress in Data Processing and Analysis

Sub title:: September 8 - 12, 1990, Dresden, GDR

Scope:: 1 Online-Ressource (396 Seiten)

Year of publication:: 1990

Place of publication:: Berlin

Publisher of the original:: Kammer der Technik

Identifier (digital):: 856470848

Illustration:: Illustrationen, Diagramme

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Monograph

Collection:: Earth sciences

Chapter

Title:: [S 3 Analytical Instruments (WG II / 1)]

Document type:: Monograph

Structure type:: Chapter

Chapter

Title:: Digital Photogrammetric Applications with the Prime-Wild S9 Analytical Plotter. David Wilkins

Document type:: Monograph

Structure type:: Chapter

36 with Stuttgart University, developed a system on the Planicomp C 100 analytical plotter (Giilch, 1984; Pertl, 1984), whilst Kern of Switzerland introduced the Kern Correlator, based on the DSR11 (Bethel, 1986). The third major European manufacturer, Wild Heerbrugg of Switzerland, did not attempt similar efforts using any of their range of analytical instruments. However, outside of the commercial field, some work has been done at ETH Zürich on a modified AC1, also mainly with a view to automatic DTM generation (Baltsavias, 1988). The experience gained with this instrument provided a basis for much of the work done on the S9AP. 2.2 Aspects of the S9AP Construction The S9AP is an integral part of System-9, the geographic information system (GIS) launched by Wild Heerbrugg in 1985. It is well documented in the literature (eg Schneeberger and Bürgermeister, 1987), but some aspects of the hardware construction must be outlined as they have implications on the work of the project. The viewing system of the instrument is of particular interest. The design of the S9AP was based on the existing BC range of instruments, rather than the AC1 which was known to be of slightly higher accuracy. The essential difference between the two is the means of image measurement: in the AC1, the entire optical train remains fixed whilst the photo carriage moves in two directions; in the BC range and in the S9AP, the carriage moves only in the Y direction, whilst measurement in the X direction is effected by translation within the optical train. The major advantage of this is a reduction in the size of the instrument, at the cost of a small reduction in accuracy in the case of measurements by manual operator. The consequences for digital measurements are somewhat more significant, however, as will later be described. Plate positioning is done via a feedback loop using servo motors and linear encoders of 1 pm resolution. Instrument calibration relates the linear encoder scales to a stage coordinate system defined by a grid of crosses engraved on each photo carriage, the relative positions of which are determined to high accuracy in the factory before installation. The quality of this calibration can be affected by the optical design as described above. 2.3 The S9AP with CCD Cameras The S9AP at ETH Zürich has a modification allowing the attachment of most types of CCD camera. The optical and structural design and implementation of this modification was carried out by Wild engineers in Heerbrugg, with the consequence that the instrument in its manual use loses nothing in terms of optical quality. The important features of this realisation are: • The cameras are mounted externally at the rear of the instrument via a C-mount fitting. Any camera using such a standard thread can be simply “screwed on”. • The magnification is approximately unity. It can be changed by a translation of the objective lens, but only within a small range. The lens is, however, not easily accessible. • The distance of the camera from the stage plate is rather long, having the disadvantage that systematic effects arising from the opto mechanical design are somewhat magnified. On the other hand, the long focal length of the objective lens (~ 30 cm) means that any effects of distortion are minimised. Figure 1 shows the relevant part of the S9AP optics and the positioning of the camera (one side only). Figure 1. Part of the S9AP optical train showing positioning of the CCD camera mount. The camera used for the investigations was the Sony XC-77CE, an inter-line transfer device with pixel size 13.6 x 11.1 pm on the stage, giving an image size of 8.0 x 6.4 mm. The image acquisition hardware used comes from the Maxvideo family of products manufactured by Datacube Inc in the USA. The boards operate on the VMEbus, thereby allowing all system components - host computer, S9AP and image acquisition hardware - to be controlled as a single system from one workstation. 3. System Calibration 3.1 Purpose of Calibration The primary purpose of calibration in the context of an analytical plotter fitted with CCD cameras is to derive a relationship between the acquired digital images and the analogue imagery being digitised. Once this relationship is determined, it is also necessary to know about its accuracy and stability. Both are influenced by many factors, and hence the whole procedure encompasses many

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