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

Damen, M. C. J.

Bibliographic data

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:: 856343064

Title:: Remote sensing for resources development and environmental management

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

Scope:: XV, 547 Seiten

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856343064

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(26,7,1)

Language:: English

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

Editor:: Damen, M. C. J.

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:: 1 Visible and infrared data. Chairman: F. Quiel, Liaison: N J. Mulder

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: New approach to semi-automatically generate digital elevation data by using a vidicon camera. C. C. Lin, A. J. Chen & D. C. Chern

Document type:: Multivolume work

Structure type:: Chapter

52 distance Fig. 2. Two level image of contour line the preprocessing is to produce a black-and-white contour line image that meets the following requirements : (i) Noises, e.g.•intermediate grayness, superfluous spikes and dots should be removed. (ii) Each contour line should be an unbroken curve, either start and end at the edge of the image, or be a closed curve by itself. (iii) Each contour line should represent one elevation value only. In other words, contour lines are not allowed to intersect with each other. (iv) Each contour line should be one pixel in thickness. However, for our purpose this is not essential. The preprocessing consists of the following steps: Step 1. Take the image of a blank white paper with the vidicon camera, then substract it from the image to be processed. This step eliminates the background noises originated from the environment. Step 2. Using the technique of threshold to produce a two-level image (Fig.2). (Duda & Hart, 1973, Rosenfeld & Kek, 1982) Step 3. Isolated dots can be eliminated by medium filtering(Pratt, 1978). Step 4. Thinning of the contour line can be carried out by the methods suggested by (Japouetti(1984). Step 5. Spurious spikes should be removed. Entangled curves should be separated. Some contour lines may become broken in the foregoing 4 steps, and thus, they have to be mended. Step 6. Each contour line should be labeled with the elevation value. The steps 1-4 can be carried out automatically, but the last two steps have to be done, at the best, semi-automatically. An interactive processing system, such as IDIMS (Interactive Digital Image Manipulation System by TRW/ESL), affords great facilities for these steps. then Z 1 However, Z 2 , and at P is where i weighting decreseii 1/D(P,Z) Some c closed cc a terra: and the above f different simplici same ele or valle the re prepoces resel. applied i 5. A fast Fig. 3. The effective distance between two points P and Q within a resel is the minimum length of all j n a j possible paths that connect P and Q within the resel. by a p a j Heavy solid lines are the contour line, and dotted With th« lines are the possible paths within the resel. The last sect dash-dotted line has the minimum length of all possible paths. Note that all the line segments are E(i, either horizontal, vertical or slant with 45°. Subscript Dg) assc For f c ' 0 if i-m=0 and j-n=0 method is ^(P,Q)= 1 I if either one of the (i-m) and and E's. (j-n) is zero essentia] , J if both (i-m) and (j-n) are not (1) Ir zero line, lc contour The ratio I/J is /2 for Euclidean distance. For easy line, le computation, we find it adequate to let J=3 and 1=2. E^=Eg=0 A "path" C consists of a series adjacent points P (ii.ji). PzUz.jz) PkUk.Jk-). The length of this path is defined as L(C)= JE ^(P a »Pi+i)- The effective distance between two points P,Q within a resel is, then defined as D(P,Q)=Min L(C K ) k Where C K represents all possible paths within the resel that connects P and Q (see Fig.3). Now, let Z denote a contour line which delineates the resel, and P denotes any point on Z. The effective distance between a point Q within the resel to Z is then defined as D(Q,Z)=Min D(Q,P) p«z d 4 m- D.CI- V'- C* < < - E, < 1- E t < 1 - 3. Effective distance within a resel A resel is a connected blank area within a contour line image. It is always bounded by one or more contour lines and, sometimes, by the edge of the image. Let's define the effective distance between two adjacent pixels, P(i,j) and Q(m,n) with |i-m|<l, |j-n|<1, as follows: 4. Interpolation Scheme For a given resel, in addition to the bordering contour lines, there may exist some closed contour lines or isolated peaks within it. Let denote these as Z i, Z2 and their elevation values as Ei, E2 For each interior point P of this resel, we choose two lines with different E's which are the nearest ones to P in terms of the effective Fig. 4. ' pixel. T] for the (5), (6) scanning i

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