The role of digital components in photogrammetric instrumentations

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Monograph

Persistent identifier:: 830281363

Title:: The role of digital components in photogrammetric instrumentations

Sub title:: symposium of Torino, Italy ; 2nd - 4th October 1974

Scope:: ca. 200 Seiten in getrennter Zählung

Year of publication:: 1974

Place of publication:: Torino, Italy

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 830281363

Illustration:: Illustrationen, Diagramme

Signature of the source:: T 15 B 1280

Language:: English

Additional Notes:: Literaturangaben

Other Title:: Nebentitel: Digital components in photogrammetric devices

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

Corporations:: International Society for Photogrammetry, Commission, 2

Adapter:: International Society for Photogrammetry, Commission, 2

Founder of work:: International Society for Photogrammetry, Commission, 2

Other corporate:: International Society for Photogrammetry, Commission, 2

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2015

Document type:: Monograph

Collection:: Earth sciences

Chapter

Title:: TRENDS IN DESIGN OF DIGITAL EQUIPMENT FOR PHOTOGRAMMETRIC INSTRUMENTS. U. V. Helava

Document type:: Monograph

Structure type:: Chapter

2 usually measure such mechanical motions to permit recording of their magnitudes. However, neither the physical motion, nor recording are necessary in a digital system; the magnitude is what counts. It may be then processed through numerous steps before its impact appears in a numerical or physical output quantity. In their capacity as generators of magnitude inputs to digital systems, the encoders perform functions equivalent to any of the physical motions in an analog instrument. Al though the encoders are only one of several ways in which inpu£ data may be entered, they do provide a clear illustration of the replacement potential. Digital replacement of geometric transformations performed by analog means has been amply demonstrated by analytical triangulation methods, and by analytical plotters. This substitution goes beyond mere replace ment in that it offers undeniable advantages in accuracy and flexibility. This applies to stereo instruments, as well as to single photo devices. [1], [2], [3], [4] It also includes the geometric manipulations involved in the photogrammetric orientation function. This task, which is basic ally mathematical, gives an opportunity for a very advantageous replace-? ment: rigorous mathematical treatment replacing a "soft" empirical technique. As long as we work with photographs as inputs and mt.p manuscripts or orthophotographs as outputs, the digital system needs an element capable of transforming a digital magnitude to a physical motion. This is in effect the inverse of what the encoder does, and is efficiently performed by a digital servo. The function is a direct replacement of analog motions involved in scanning the photographs or plotting the manu scripts. It may be of interest to note that the servo usually includes an encoder as a feedback element; it tells the servo what is the magni tude of physical motion the servo has introduced. A comparison of this with the desired digital value gives the servo the information it needs to introduce additional motion. The list of replacement possibilities can be extended further to cover various control and display functions. It is more important, however, to recognize that the scope of digital functions in photogram- metjric instruments extends far beyond that: it includes totally new functions, such as post-processing of photograrametrically derived data. The "Automatic Draftsman" [5] is a case in point. It can improve the manuscript and thus perform a function not found in analog instruments. It is the responsibility of the designers of photogrammetric instru ments, particularly those who are concerned about digital components, to make sure that the photogrammetric instrument users will get full economic benefits from the state of the art in digital equipment field. The task is not easy. Digital technology advances at an extremely fast rate, driven by its immense economic potential. New devices are announced nearly every day, and complete new generations of implementation approaches

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