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comparison gnv-artifacts/src/main/java/de/intevation/gnv/math/Interpolation2D.java @ 528:44415ae01ddb

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Fixed issue gnv/issue159 gnv-artifacts/trunk@624 c6561f87-3c4e-4783-a992-168aeb5c3f6f
author Sascha L. Teichmann <sascha.teichmann@intevation.de>
date Mon, 25 Jan 2010 18:25:19 +0000
parents 4e347624ee7c
children 9a828e5a2390
comparison
equal deleted inserted replaced
527:f598702b2a10 528:44415ae01ddb
26 } // interface Consumer 26 } // interface Consumer
27 27
28 private Interpolation2D() { 28 private Interpolation2D() {
29 } 29 }
30 30
31 public static Envelope pathBoundingBox( 31 public static final Envelope relevantArea(
32 List<? extends Coordinate> path, 32 List<? extends Coordinate> path,
33 double extra 33 List<? extends Coordinate> points
34 ) {
35 return relevantArea(path, points, CULL_POINT_THRESHOLD);
36 }
37
38 public static final Envelope relevantArea(
39 Envelope pathBBox,
40 List<? extends Coordinate> points
41 ) {
42 return relevantArea(pathBBox, points, CULL_POINT_THRESHOLD);
43 }
44
45 public static final Envelope relevantArea(
46 Envelope pathBBox,
47 List<? extends Coordinate> points,
48 int threshold
49 ) {
50 return points.size() < threshold
51 ? null
52 : relevantArea(
53 pathBBox,
54 pointsBoundingBox(points));
55 }
56
57 public static final Envelope relevantArea(
58 List<? extends Coordinate> path,
59 List<? extends Coordinate> points,
60 int threshold
61 ) {
62 return points.size() < threshold || path.isEmpty()
63 ? null
64 : relevantArea(
65 pointsBoundingBox(path),
66 pointsBoundingBox(points));
67 }
68
69 public static final Envelope relevantArea(
70 Envelope pathBBox,
71 Envelope pointsBBox
72 ) {
73 double pathArea = pathBBox.getWidth()*pathBBox.getHeight();
74 double pointsArea = pointsBBox.getWidth()*pointsBBox.getHeight();
75
76 if (pathArea > 0.8d*pointsArea) { return null; }
77
78 double nArea = 1.44d * pathArea;
79 if (nArea < 0.1d*pointsArea) nArea = 0.1d*pointsArea;
80 double w = pathBBox.getWidth();
81 double h = pathBBox.getHeight();
82 double [] d = solveQuadratic(1d, w+h, pathArea - nArea);
83
84 if (d == null) { return null; }
85
86 double extra = pos(d);
87
88 pathBBox.expandBy(extra);
89
90 return pathBBox;
91 }
92
93 public static final double [] solveQuadratic(
94 double a, double b, double c
95 ) {
96 double d = b*b - 4d*a*c;
97 if (d < 0d) { return null; }
98
99 d = Math.sqrt(d);
100 a = 1d/(2d*a);
101 b = -b;
102
103 return new double [] { a*(b + d), a*(b - d) };
104 }
105
106 public static final double pos(double [] x) {
107 return x[0] >= 0 ? x[0] : x[1];
108 }
109
110
111 public static Envelope pointsBoundingBox(
112 List<? extends Coordinate> path
34 ) { 113 ) {
35 int N = path.size(); 114 int N = path.size();
36 Envelope area = new Envelope(path.get(N-1)); 115 Envelope area = new Envelope(path.get(N-1));
37 116
38 for (int i = N-2; i >= 0; --i) { 117 for (int i = N-2; i >= 0; --i) {
39 area.expandToInclude(path.get(i)); 118 area.expandToInclude(path.get(i));
40 } 119 }
41
42 area.expandBy(
43 extra*area.getWidth(),
44 extra*area.getHeight());
45 120
46 return area; 121 return area;
47 } 122 }
48 123
49 public static void interpolate( 124 public static void interpolate(
67 142
68 if (M < 1 || N < 2) { // nothing to do 143 if (M < 1 || N < 2) { // nothing to do
69 return; 144 return;
70 } 145 }
71 146
72 Envelope relevantArea = M > CULL_POINT_THRESHOLD
73 ? pathBoundingBox(path, 0.05d)
74 : null;
75
76 List<GridCell> cells = GridCell.pointsToGridCells( 147 List<GridCell> cells = GridCell.pointsToGridCells(
77 points, relevantArea); 148 points, relevantArea(path, points));
78 149
79 if (cells.isEmpty()) { 150 if (cells.isEmpty()) {
80 log.warn("no cells found"); 151 log.warn("no cells found");
81 return; 152 return;
82 } 153 }
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