XVIIIth Congress: XVIIIth Congress

kraus, karl; waldhäusl, peter

Bibliographic data

Multivolume work

Persistent identifier:: 1667435949

Title:: XVIIIth Congress

Sub title:: Vienna, Austria 1996

Year of publication:: 1996

Place of publication:: Vienna

Publisher of the original:: Austrian Society of Surveying and Geoinformation

Identifier (digital):: 1667435949

Language:: English

Editor:: Kraus, Karl; Waldhäusl, Peter

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Document type:: Multivolume work

Volume

Persistent identifier:: 1667437070

Title:: XVIIIth Congress

Scope:: 230 Seiten

Year of publication:: 1996

Place of publication:: Vienna

Publisher of the original:: Austrian Society of Surveying and Geoinformation

Identifier (digital):: 1667437070

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(31,B1)

Language:: English

Additional Notes:: Erscheinungsdatum des Originals ist anhand des Copyrightjahrs ermittelt.

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

Editor:: Kraus, Karl; Waldhäusl, Peter

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2019

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: TRANSPORTABLE TEST-BAR TARGETS AND MICRODENSITOMETER MEASUREMENTS - A METHOD TO CONTROL THE QUALITY OF AERIAL IMAGERY R. Kuittinen, [...] E. Ahokas, [...] P. Järvelin, [...]

Document type:: Multivolume work

Structure type:: Chapter

tion can ial influ- on Is to ig phase erval on al kine- y stereo mina l., Verlag, inn, F: ination ic Engi- . 1315- on us- ceeding "inland, tudy on project hives of 34, pp. d point on im- rveyors immet- agery", ing and 9. 61155 on and roceed- 1-484, evalua- opia)", ng and 02-114 IC pro- gress - y 9-19, or the )ases", rmany, plution | from Hobbie Isruhe, TRANSPORTABLE TEST-BAR TARGETS AND MICRODENSITOMETER MEASUREMENTS - A METHOD TO CONTROL THE QUALITY OF AERIAL IMAGERY R. Kuittinen, Finnish Geodetic Institute, Geodeetinrinne 2, 02430 Masala, Finland E. Ahokas, Finnish Geodetic Institute, Geodeetinrinne 2, 02430 Masala, Finland P. Jürvelin, University of Jyváskylà, Department of Physics, PL 35, 40351 Jyváskylà, Finland ISPRS Commission I, Working Group 1 KEY WORDS: Quality, Control, Targets, Imagery, Measurement ABSTRACT Transportable polyester plastic test bar targets were made and used to test their usefulness for determining the spatial resolution of aerial photography. The results show that it is possible to construct and measure by microdensitometer light transportable targets to test the spatial resolution of aerial photography. 1. INTRODUCTION High quality is usually important for the user of aerial photographs regardless of whether they are used by the photographer or other users. When processing a photogrammetric task the quality of the camera, film and navigation devices are usually known and the task is carried out using controlled methods. Thus the quality of the photographs can be estimated in advance which is the basis for a good result. In practice, however, some unpredictable factors like atmospheric characteristics, defects in the camera, irregular movements of the platform, rapid changes in terrain radiances or problems in the film development process can significantly lower the quality of the images. To be able to monitor the quality of aerial photographs, objective testing methods are needed. The main quality criteria of aerial photography are spatial resolution, geometric accuracy and the correctness of grey tones or the colours in the image. A lot of factors affect these criteria, (Hakkarainen et al., 1992). The spatial resolution of the image has been selected here as the only quality criterion, because the most important of these factors like poor transmittance of the atmosphere, camera, film or development process reduce the spatial resolution and thus the quality of the image. The only objective method to test the spatial resolution of films or images is to use standardized test fields with known figures, contrasts and reflectances. These permanent fields are very few in number and usually used only for testing the quality of imaging systems. The fields cannot be used to control the quality of operational aerial photography which are carried out at different places and under different circumstances. To obtain an objective method to test the spatial resolution of aerial photography wherever wanted, transportable test targets are needed. In summer 1995 the Finnish Geodetic Institute carried out an experiment to test the usefulness of transportable test targets. The idea of the targets is that they are so small and light that they can be placed in the terrain at the same time as the targeting of control points is made. The results of the experiment are presented in this paper. 99 2. METHOD 2.1 Targets To be easy to transport the test target must be light in weight so that it can be transported to the area which will be photographed. The lightness of the targets were reached in two ways. The targets were made of strong polyester plastic which is light compared with wood or metal plates. The size of the target was made small by using continuously changing bar widths. This means that the width of the bars and the backgrounds decreases according to a selected constant. This reduces the length of the target by a factor of four or at least three. The bars were painted on the plastic using suitable paints (two grey tones). The reflectances and the contrasts of the painted bars and the background correspond approximately to green grass and bare soil. Thus the targets offer good possibilities to evaluate the spatial resolution of the images when rural areas are photographed. The size of the target depends on the scale of the photography and will be made as small as possible. In 1995 test targets for 1:3 000 and 1:60 000 scale aerial photography were made as Table 1 shows. Table 2 shows the characteristics of permanent targets of the test field for 1:3 000 (C) and 1:60 000 (D) scale photography. These permanent targets were used as a reference. Figure 1 shows a B-type test target in the field. A B size of target (m^) 2.5x1.5 5.0x10.5 width of bars (cm) 3.0-12.0 53.0-212 length of bars (m) 2,5 5.0 range of spatial res. (I/mm) 25-100 28-113 weight (kg) 4 50 number of bars and back- 1 1 grounds having the same width ratio of the width between the 95 4/5 adjacent bars Table 1. The characteristics of the transportable test-bar targets for 1:3 000 (A) and 1:60 000 (B). International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B1. Vienna 1996

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