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Feature branch for tiles xy-to-quadkey conversion #1

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Feature branch for tiles xy-to-quadkey conversion #1

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1a3ca83
adding features for converting between tile number, x-/y-coordinate a…
beauof Feb 27, 2020
e82a2b5
edits w.r.t. review on PR #1
beauof Feb 28, 2020
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5 changes: 5 additions & 0 deletions pom.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,11 @@
<artifactId>junit</artifactId>
<version>4.1</version>
</dependency>
<dependency>
<groupId>com.vividsolutions</groupId>
<artifactId>jts</artifactId>
<version>1.13</version>
</dependency>
</dependencies>
<build>
<plugins>
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18 changes: 18 additions & 0 deletions src/main/java/de/rondiplomatico/nds/NDSCoordinate.java
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Expand Up @@ -96,6 +96,24 @@ public NDSCoordinate(long ndsMortonCoordinates) {
latitude = lat;
longitude = lon;
}

/*
* Computes a point along the distance of this and given NDSCoordinate
*
* @param p
* the given coordinate
* @param fraction
* the fraction
*/
public NDSCoordinate fractionBetween(NDSCoordinate p, double fraction) {
assert (0.0 <= fraction) && (fraction <= 1.0);
double lat = p.toWGS84().getLatitude();
double lon = p.toWGS84().getLongitude();
WGS84Coordinate lonlat = toWGS84();
double longitude = lonlat.getLongitude();
double latitude = lonlat.getLatitude();
return new NDSCoordinate(longitude + fraction * (lon - longitude), latitude + fraction * (lat - latitude));
}

private void verify(int lon, int lat) {
if (lat < MIN_LATITUDE || MAX_LATITUDE < lat) {
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138 changes: 138 additions & 0 deletions src/main/java/de/rondiplomatico/nds/NDSEnvelope.java
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@@ -0,0 +1,138 @@
package de.rondiplomatico.nds;

import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.OctagonalEnvelope;

/**
* NDSEnvelope allows to compute an envelope for a set of NDSCoordinates.
*
* No warranties for correctness, use at own risk.
*
* @author Andreas Hessenthaler
* @since 13.02.2020
*/
public class NDSEnvelope {

private static OctagonalEnvelope vividEnvelope = new OctagonalEnvelope();

/**
* NDSEnvelope of a given set of polygon points
*
* @param polygonCoordinates
* the polygonCoordinates
*/
public NDSEnvelope(double[][] polygonCoordinates) {
for(int i = 0; i < polygonCoordinates.length; i++) {
Coordinate vividCoord = new Coordinate(polygonCoordinates[i][0], polygonCoordinates[i][1]);
vividEnvelope.expandToInclude(vividCoord);
}
}

/**
* NDSEnvelope constructor for OctagonalEnvelope
*
* @param e
* the OctagonalEnvelope e
*/
public NDSEnvelope(OctagonalEnvelope e) {
vividEnvelope = e;
}

/**
* Get the NDSEnvelope
*
* @return
*/
public OctagonalEnvelope getEnvelope() {
return vividEnvelope;
}

/**
* Get the SouthWest corner of the envelope
*
* @return
*/
public NDSCoordinate getSouthWest() {
return new NDSCoordinate(vividEnvelope.getMinX(), vividEnvelope.getMinY());
}

/**
* Get the SouthEast corner of the envelope
*
* @return
*/
public NDSCoordinate getSouthEast() {
return new NDSCoordinate(vividEnvelope.getMaxX(), vividEnvelope.getMinY());
}

/**
* Get the NorthEast corner of the envelope
*
* @return
*/
public NDSCoordinate getNorthEast() {
return new NDSCoordinate(vividEnvelope.getMinX(), vividEnvelope.getMaxY());
}

/**
* Get the NorthWest corner of the envelope
*
* @return
*/
public NDSCoordinate getNorthWest() {
return new NDSCoordinate(vividEnvelope.getMaxX(), vividEnvelope.getMaxY());
}

/**
* Get the master tile for the SouthWest, SouthEast, NorthEast, NorthWest corners for a given number of levels
*
* @param maxLevels
* the maxLevels
* @return masterTileInfo
* the masterTileInfo consisting of the {masterTileLevel, masterTileNumber}
*/
public int[] getMasterTileInfo(int maxLevels) {
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NDSCoordinate point0 = getSouthWest();
NDSCoordinate point1 = getSouthEast();
NDSCoordinate point2 = getNorthEast();
NDSCoordinate point3 = getNorthWest();
return getMasterTileInfo(point0, point1, point2, point3, maxLevels);
}

/**
* Get the master tile for a set of four NDSCoordinates for a given number of levels
*
* @param maxLevels
* the maxLevels
* @return masterTileInfo
* the masterTileInfo consisting of the {masterTileLevel, masterTileNumber}
*/
public int[] getMasterTileInfo(NDSCoordinate point0, NDSCoordinate point1, NDSCoordinate point2, NDSCoordinate point3, int maxLevels) {
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what does the master tile info consist of? what does it give me if i invoke this method?

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It returns the {masterTileLevel, masterTileNumber}, i.e. the tile level and number of the tile fully enclosing these points.

int masterTileLevel = -1;
int masterTileNumber = -1;
for (int li = 0; li < maxLevels; li++) {
NDSTile currTile0 = new NDSTile(li, point0);
NDSTile currTile1 = new NDSTile(li, point1);
NDSTile currTile2 = new NDSTile(li, point2);
NDSTile currTile3 = new NDSTile(li, point3);
int currTileNumber0 = currTile0.getTileNumber();
int currTileNumber1 = currTile1.getTileNumber();
int currTileNumber2 = currTile2.getTileNumber();
int currTileNumber3 = currTile3.getTileNumber();
boolean singleTileNumber = (currTileNumber0 == currTileNumber1) && (currTileNumber0 == currTileNumber2) && (currTileNumber0 == currTileNumber3);
// if at least one tile ID is different, we discard the tile IDs and keep our previously detected tile ID (i.e. on the previous level)
if(!singleTileNumber) {
break;
}
// store tile info
masterTileLevel = li;
masterTileNumber = currTileNumber0;
}
// check if valid result
if (masterTileNumber == -1) {
System.out.println(">>>ERROR: Invalid master tile ID.");
System.exit(1);
}
return new int[] {masterTileLevel, masterTileNumber};
}
}
214 changes: 214 additions & 0 deletions src/main/java/de/rondiplomatico/nds/NDSFloodFill.java
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package de.rondiplomatico.nds;

import java.awt.Point;
import java.util.LinkedList;
import java.util.Queue;

/**
* Utility class for flood fill algorithm applied to marked NDSTiles deduced from polygon points.
*
* @author Andreas Hessenthaler
* @since 13.02.2020
*/
public class NDSFloodFill {
int[][] ff = null;
int minX = Integer.MAX_VALUE;
int maxX = Integer.MIN_VALUE;
int minY = Integer.MAX_VALUE;
int maxY = Integer.MIN_VALUE;
int dimX = -1;
int dimY = -1;
int bg = 0;
int bound = 1;
int fill = bound;
int startAtX = 0;
int startAtY = 0;

/**
* Constructor
*
* @param f
* the image input to perform flood fill on
* assumes:
* - non-empty array
* - closed polygon without intersections with boundary color 1 and background color 0
* @param a
* the minimum x-index
* @param b
* the maximum x-index
* @param c
* the minimum y-index
* @param d
* the maximum y-index
*/
public NDSFloodFill(int[][] f, int a, int b, int c, int d) {
ff = f;
minX = a;
maxX = b;
minY = c;
maxY = d;
dimX = maxX - minX + 1;
dimY = maxY - minY + 1;
setStartingPoint();
}

/*
* Iterative four-way flood fill algorithm
*
*/
public void iterativeFloodFill() {
Queue<Point> q = new LinkedList<Point>();
q.add(new Point(startAtX, startAtY));
while (!q.isEmpty()) {
Point p = q.remove();
if ((p.x < 0) || (p.y < 0) || (p.x > dimX-1 || (p.y > dimY-1))) {
continue;
}
if (ff[p.x][p.y] == bg) {
ff[p.x][p.y] = fill;
q.add(new Point(p.x+1, p.y )); // right
q.add(new Point(p.x, p.y+1)); // top
q.add(new Point(p.x-1, p.y )); // left
q.add(new Point(p.x, p.y-1)); // bottom
}
}
}

/*
* Safety net for filling left over lines after applying flood fill algorithm
*
*/
public void fillHoles() {
// first, find vertical lines
boolean vline = false;
boolean vlineEnded = false;
int currStartY = -1;
int currStopY = -1;
for (int col = 1; col < dimY-1; col++) {
vline = false;
vlineEnded = false;
for (int row = 1; row < dimX-1; row++) {
// minimum requirement: left and right neighbors are not background
if ((ff[row][col-1] != bg) && (ff[row][col+1] != bg)) {
if ((ff[row][col] == bg)
&& (ff[row-1][col] != bg)) {
// beginning of vertical line
currStartY = row;
vline = true;
} else if (vline && (ff[row][col] == bg)) {
// vertical line continues
} else if (vline && (ff[row][col] != bg)) {
// end of vertical line
currStopY = row;
vlineEnded = true;
}
} else if (vline && ((ff[row][col+1] != bg) || (ff[row][col-1] != bg)) && (ff[row][col] != bg)) {
// end of horizontal line
currStopY = row;
vlineEnded = true;
} else {
vline = false;
vlineEnded = false;
}
if (vline && vlineEnded) {
// fill line and reset booleans
System.out.println(">>>>>>INFO: Filling vertical line.");
for (int idx = currStartY; idx < currStopY; idx++) {
ff[idx][col] = fill;
}
vline = false;
vlineEnded = false;
}
}
}
// second, find horizontal lines
boolean hline = false;
boolean hlineEnded = false;
for (int row = 1; row < dimX-1; row++) {
hline = false;
hlineEnded = false;
for (int col = 1; col < dimY-1; col++) {
// minimum requirement: top and bottom neighbors are not background
if ((ff[row+1][col] != bg) && (ff[row-1][col] != bg)) {
if ((ff[row][col] == bg)
&& (ff[row][col-1] != bg)) {
// beginning of horizontal line
currStartY = col;
hline = true;
} else if (hline && (ff[row][col] == bg)) {
// vertical line continues
} else if (hline && (ff[row][col] != bg)) {
// end of vertical line
currStopY = col;
hlineEnded = true;
}
} else if (hline && ((ff[row+1][col] != bg) || (ff[row-1][col] != bg)) && (ff[row][col] != bg)) {
// end of vertical line
currStopY = col;
hlineEnded = true;
} else {
hline = false;
hlineEnded = false;
}
if (hline && hlineEnded) {
// fill line and reset booleans
System.out.println(">>>>>>INFO: Filling horizontal line.");
for (int idx = currStartY; idx < currStopY; idx++) {
ff[row][idx] = fill;
}
hline = false;
hlineEnded = false;
}
}
}

return;
}

/*
* Set initial point for flood fill algorithm
*
* @todo need to do more extensive checks if we can always find an initial point if we only check the right half of the box
*/
private void setStartingPoint() {
startAtX = (int) (0.5 * dimX);
startAtY = 0;
// we're starting on background, skip that..
while (ff[startAtX][startAtY] == bg) {
startAtY++;
}
// we're continuing on an edge, skip that..
while (ff[startAtX][startAtY] == bound) {
startAtY++;
}
for (int row = startAtY; row < dimY; row++, startAtY++) {
int rowSum = 0;
for (int col = startAtX; col < dimX; col++) {
if (ff[col][row-1] != ff[col][row]) {
rowSum = rowSum + ff[col][row];
}
}
if ((rowSum % 2) == 1) {
// we've found a point that's inside
break;
}
}
return;
}

/*
* Get initial point for flood fill algorithm
*
*/
public int[] getStartingPoint() {
return new int[] {startAtX, startAtY};
}

/*
* Get flood filled image
*
*/
public int[][] getFloodFill(){
return ff;
}
}
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