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:: THE SUFFICIENT AREA CONDITION OF AN OBJECT FOR A SPOT-DETECTOR F. Cheng and Ph. Hartl

Document type:: Multivolume work

Structure type:: Chapter

THE SUFFICIENT AREA CONDITION OF AN OBJECT FOR A SPOT- DETECTOR F. Cheng* and Ph. Hartl Institute for Navigation, University of Stuttgart, Stuttgart, Germany KEY WORDS: SPOT-pixel, spatial resolution ABSTRACT: Some objects can not be found or identified on a SPOT-image due to their too small areas. An Object on the ground must be large enough so that it can be detected vertically by a SPOT-detector and recorded as a complete pixel in a SPOT-image. This condition, defined as the sufficient area condition, has been not studied yet. In this paper the condition is theoretically analysed and quantitatively calculated. It may be expressed as follows: 1) the area of an object on the ground must include an ellipse, whose long axis e, is in the direction with the greatest ground slope € and equal to 2R/ cos€ , and whose short axis e, is horizontal and equal to 2R; 2) if the ground is smooth (€ =0), the ellipse becomes a circle with the radius R. Here R is the diagonal length of a SPOT-image's pixel: 10/2 m or 20/2 m. 1. INTRODUCTION Some objects can not be found or identified on a SPOT- image due to their too small areas. How large should the area of an object on the ground be, so that it can be detected at least by a SPOT-detector? Many people have met such a question in their works, especially in classifying or identifying objects on satellite images. Some of them hope to use satellite data with smaller pixel size or higher spatial resolution in order to obtain better results (Begni 1988, Dowman et al 1989, Moore et al 1989, Jensen et al 1993, Manavalan et al 1993, Cheng et al 1995, Hartl et al 1995). There are two types of SPOT-images: vertical and oblique viewing images. Here only the former is discussed. The area of an object on the ground, which makes the object to be vertically detected at least by a SPOT-detector and be recorded as a complete pixel in a SPOT-image, is defined as the sufficient area condition. This paper shows the study of the condition and gives its mathematical expression. 2. THE SUFFICIENT AREA CONDITION ON THE SMOOTH GROUND 2.1 Position change of grids The figure 1 shows a square grid, which represents the corresponding area of a SPOT-detector on the smooth ground. Here we call it a SPOT-detector-grid (G- side length; d- diagonal length). Suppose that there is a circular object C, with the radius R on the ground. On the object a Cartesian coordinate system oxy is set up, whose origin o is at the center of the object and whose y- axis points north. Suppose that the center of a SPOT- detector-grid (p) is just overlapped with the object's center and f,, f,, ...f, are the eight neighbour grids of the grid p (figure 2). In this situation the object can be detected at "Present address: Company for applied Remote Sensing (GAF), 80636 Munich, Germany 36 least by a complete SPOT-detector-grid, if its radius R meets the following condition: gaz 1 2 t (1) This is a special situation. But it may be supposed that the grids' position shown in the figure 2 is the original position. The position of the grids on the ground generally changes after a revolving period of the satellite. The figure 3(1) shows such a change. The grids have left the original position in a new revolving period. We may only consider the position change of the grid p instead of all the grids, because the relative position between the different grids is fixed. The position change of the grid p shown in the figure 3(1) can be resolved into a shift and a turn around the origin o. i) The grid p shifts first from o to p' and then ii) it turns around o from p' to p" (figure 3(2)). In fact any position change of the grids can be resolved as above. Suppose that the grid p shifts first from the original position (0,0) to an other position (xp, yp) (figure 4(1)). The shift amount is equal to the distance between the two points. We define X as the component of this distance on the x-axis and Y as its component on the y-axis. Then the following equalities are tenable: X =Ixp| and Y =lypl. In the situation shown in the figure 4(1) the object C, can be detected by a complete SPOT-detector-grid, if its radius R meets: a: 22 ap R=] Cre ++) | (2) See the figure 4(2). The grid p turns around o in the next revolving period of the satellite. Then R should meet: 2 [ a ie. ti R= (X3 cos p + +3) sin p | + 2 are) X42) si ( 3 cos p — ( +2) sin p 2 International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B1. Vienna 1996 It is deman of the « to bec 2.2 SI The lo obviou See th origina are sm equal ; figure . Ris lc In fac distanc change a ) 2 The fic the ne center comple to incl are for at intei The gr axis a distanc grid p. 2)0« The fic similar the eq € a/2 e 3) —=« 2 See th as the Ixzl € e 4) IXpl | See th the st neighk Ixel < « the gri Theref a/2. TI Xsa radius shoulc

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