Remote sensing for resources development and environmental management: Remote sensing for resources development and environmental management

damen, m. c. j.

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Multivolume work

Persistent identifier:: 856342815

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856342815

Language:: English

Additional Notes:: Volume 1-3 erschienen von 1986-1988

Editor:: Damen, M. C. J.

Document type:: Multivolume work

Volume

Persistent identifier:: 856641294

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Scope:: IX Seiten, Seiten 551-956

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A,. A. Balkema

Identifier (digital):: 856641294

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(26,7,2)

Language:: English

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

Editor:: Damen, M. C. J.

Editor:: International Society for Photogrammetry and Remote Sensing, Commission of Photographic and Remote Sensing Data

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:: Volume

Collection:: Earth sciences

Chapter

Title:: 7 Human settlements: Urban surveys, human settlement analysis and archaeology. Chairman: W. G. Collins, Co-chairman: B. C. Forster, Liaison: P. Hofstee

Write comment:: Wegen zu enger Bindung kommt es teilweise im Original zu Textverlust.

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: Automatic digitizing of photo interpretation overlays with a digital photodiode camera: The ADIOS system. C. A. de Bruijn & A. J. van Dalfsen

Document type:: Multivolume work

Structure type:: Chapter

The size of an interpretation overlay is limited (23 x 23 cm) and the content is not very complex. Often it is only a single theme and a single line type. A typical landuse interpretation consists e.g. only of polygons that are not overlapping and which have a single attribute. Each piece of land can only belong to one polygon (one landuse). Automatic digitizing of such an overlay should be relatively easy. 4 COMPARABLE APPROACHES MEISNER (1981) from the Remote Sensing Laboratory of the University of Minnesota has been using a medium cost image processing system to obtain 640 x 480 pixel video images of map sections. An operator positions the screen cursor inside a polygon and enters the (landuse) code for that polygon. The computer then scans from the indicated point tó the left until a boundary is reached. An automatic line following routine is used to follow this boundary back to the starting point. The entire process takes 1-2 seconds for a typical polygon. LEBERL (1982) describes the use of a rather expensive flatbed scanner, the Karto Scan, for the automatic digitizing of polygon data. He used the scanner only for scanning the polygon boundaries only. Centroids with polygon labels have been digitized separately on a manual digitizer. The scanned boundary data are vectorized, using Syscan software, (before scanning, labels had to be removed from the map in a predigitial preparation step). All further processing is in vector format. The geometry of the information as digitized is the same as the geometry of the airphoto that has been interpreted. In certain cases it is possible to digitize overlays from orthophotos where the geometry is already correct, but orthophotos should not be prerequisite for the system. The overlay will be "push button" scanned in a raster mode, results are pre-processed and displayed on a high resolution color CRT. Next step is to indicate with a lightpen or cursor on the CRT lines or areas with identical codes and to enter those codes. That should be easy since all codes on the manuscript are also scanned and hence displayed on the screen. An alternative approach is to digitize the centroids of each polygon on a conventional digitizer together with its code and use this datafile for automatic coding. When a code is assigned to an area the software will look for its boundaries and paints the area with the color allocated to that code. The colored map on the screen enables easy checking by the interpreter. Editing, (deleting, changing or entering areas and boundaries) can be done either by correcting the original overlay drawing and redigitizing it, or by interactive editing at the terminal. When the colored map is correct, it may be sent to the appropriate database after applying the specified geometric correction(s). 5.2 Hardware photodiode up to 12 b computer, ; state arra; properties photolithoj 1981). Eiki pixel, cori verified, 1 its digita ITC includi compensate a computer separation (Another E The CCD hoi sensitive manufacture his earliei Using the ! overlay mei per mm or i mm line wii effective •, 5.3 The cui Fig 3 gives currently < used for A1 11/24 and < bitplanes. At the 1986 ACSM conference N.R. CHRISMAN reported on the use of a scanning system, incorporating a Data Copy 1700 x 3800 pixel CCD camera. The system is used to digitize 9 x 15 inch soilmaps. After thresholding and thinning vector output is generated that is further processed with a "spaghetti and meatballs" approach and edited to obtain a topologically correct datafile. Scanning and vectorizing a soil map took 20-30 minutes. Chrisman believes that "devices like this scanner will alter the digitizing environment to create higher quality with lower expense". Also recently published has been a description by FAIN (1985) of a commercial system, the Smart Scan System, developed by Energy Images Inc., that seems to use (according to the accompanying illustration) an Eikonix 4096 x 4096 CCD array scanning camera. The Smart Scan system outputs vector data and uses some artificial intelligence software to divide the vector data into various layers based on information how lines and symbols are represented on the document. Subsequent editing is carried out in an interactive vector graphics environment. The scanned raster data are displayed on the CRT screen with the derived vector data superimposed, so that errors can be detected easily. 5 THE ADIOS CONCEPT 5.1 How ADIOS will look to the user It is assumed that the result of an interpretation will be in the form of a (transparent) 23 x 23 cm overlay, belonging to a particular airphoto, drawn with a rapidograph pen ofO .3 mm linewidth or larger. To a limited extent it may be possible to impose certain conventions to the drawing style of the interpreter (cf norms for technical drawings that have to be microfilmed). That means that the interpreter should draw the fiducial marks in a certain way, mark tiepoints where applicable, keep text and lines separate, close or overshoot polygons etc. At present three technologies should be considered for a simple system - videodigitizing - digitizing with photodiodes or CCD’s electronic camera - low cost document scanners Typical resolution for video digitizing is 512 x 512 or 640 x 480 while for photodiodes or CCD’s 2048 x 2048 resp. 4096 x 4096 may be obtained. For the exi used (fig. 1980 for a They are tj were indeec automatic c results ob1 représentai The various The low cost document scanners introduced in 1986 have resolutions of approximately 2500 x 3500 , but little is known of their spatial accuracy as yet. They only handle up to A4 size originals and, like photocopying machines, they lack a viewfinder for orientation of the original. Some systems have the capability of handling color. Table I summarizes some characteristics. TABLE I: A4 Image Scanners Hannover CEBIT fair 1986 Type resolution dpi grey levels color OCR Ricoh IS 30 300,240,200,180 16 - _ " CS 30 " ft RGB - " FS 1 400,300,240,120 256 RGB - Compuscan PCS 200,150,100 7 - + Canon CS 220 300,200,150,75 i6 - - dpi = dots per inch ocr = optical character recognition MEISNER, already mentioned above, used a SPATIAL DATA EYECOM II Picture digitizer, a video digitizer with 640 x 480 resolution. Applied to a 9 inch photo that gives resolution of 0.4 mm which is hardly sufficient if a 0.3 mm rapidograph is used and is considerably lower than the resolution of manual digitizers (0.1 to 0.025 mm). For ADIOS, an Eikonix 78/99 digital camera has been selected with a linear 2048 element photodiode array mounted in a motor driven stage (fig.2) that moves in 2048 steps equal to the distance between the photodetectors (15/im). The voltage of each Step 1 scai In scanninj to éliminai on the ovei interpretit values of 1 completely edge enhane Step 2 edge Although tl displayed < pixels are - unequal - varyinj - varyinj In the pres photographe incandescei found that Some of the those of se areas on o1 unprocessee (dark linei thresholdii connectivi1 noise, (fij To "reconst enhancement factors

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