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MVT simplification (#956)

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Emux 2022-08-24 15:39:01 +03:00 committed by GitHub
parent 7b0a5249b7
commit 575c2c2b34
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3 changed files with 26 additions and 8 deletions
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2
docs/Changelog.md
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@ -2,6 +2,8 @@
## New since 0.18.0
- MVT simplification [#956](https://github.com/mapsforge/vtm/pull/956)
- `Parameters.SIMPLIFICATION_TOLERANCE`, `Parameters.SIMPLIFICATION_EXCEPTIONS`
- Minor improvements and bug fixes
- [Solved issues](https://github.com/mapsforge/vtm/issues?q=is%3Aclosed+milestone%3A0.19.0)

30
vtm-mvt/src/org/oscim/tiling/source/mvt/TileDecoder.java
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@ -1,6 +1,6 @@
/*
* Copyright 2014 Hannes Janetzek
* Copyright 2017 devemux86
* Copyright 2017-2022 devemux86
* Copyright 2018 boldtrn
*
* This file is part of the OpenScienceMap project (http://www.opensciencemap.org).
@ -23,17 +23,26 @@ import com.wdtinc.mapbox_vector_tile.adapt.jts.TagKeyValueMapConverter;
import com.wdtinc.mapbox_vector_tile.adapt.jts.model.JtsLayer;
import com.wdtinc.mapbox_vector_tile.adapt.jts.model.JtsMvt;
import org.locationtech.jts.geom.*;
import org.locationtech.jts.simplify.TopologyPreservingSimplifier;
import org.oscim.core.MapElement;
import org.oscim.core.Tag;
import org.oscim.core.Tile;
import org.oscim.tiling.ITileDataSink;
import org.oscim.tiling.source.ITileDecoder;
import org.oscim.utils.Parameters;
import java.io.IOException;
import java.io.InputStream;
import java.util.Map;
public class TileDecoder implements ITileDecoder {
/**
* Reduce points on-the-fly while reading from vector maps.
*/
public static int SIMPLIFICATION_MIN_ZOOM = 8;
public static int SIMPLIFICATION_MAX_ZOOM = 11;
private final String mLocale;
private static final float REF_TILE_SIZE = 4096.0f;
@ -71,14 +80,14 @@ public class TileDecoder implements ITileDecoder {
for (JtsLayer layer : jtsMvt.getLayers()) {
for (Geometry geometry : layer.getGeometries()) {
parseGeometry(layer.getName(), geometry, (Map<String, Object>) geometry.getUserData());
parseGeometry(layer.getName(), geometry, (Map<String, Object>) geometry.getUserData(), tile.zoomLevel);
}
}
return true;
}
private void parseGeometry(String layerName, Geometry geometry, Map<String, Object> tags) {
private void parseGeometry(String layerName, Geometry geometry, Map<String, Object> tags, int zoomLevel) {
mMapElement.clear();
mMapElement.tags.clear();
@ -105,12 +114,11 @@ public class TileDecoder implements ITileDecoder {
processLineString((LineString) multiLineString.getGeometryN(i));
}
} else if (geometry instanceof Polygon) {
Polygon polygon = (Polygon) geometry;
processPolygon(polygon);
processPolygon((Polygon) simplify(geometry, zoomLevel));
} else if (geometry instanceof MultiPolygon) {
MultiPolygon multiPolygon = (MultiPolygon) geometry;
for (int i = 0; i < multiPolygon.getNumGeometries(); i++) {
processPolygon((Polygon) multiPolygon.getGeometryN(i));
processPolygon((Polygon) simplify(multiPolygon.getGeometryN(i), zoomLevel));
}
} else {
err = true;
@ -169,5 +177,13 @@ public class TileDecoder implements ITileDecoder {
if (!hasName && fallbackName != null)
mMapElement.tags.add(new Tag(Tag.KEY_NAME, fallbackName, false));
}
}
private Geometry simplify(Geometry geometry, int zoomLevel) {
if (Parameters.SIMPLIFICATION_TOLERANCE > 0
&& zoomLevel >= SIMPLIFICATION_MIN_ZOOM && zoomLevel <= SIMPLIFICATION_MAX_ZOOM) {
if (!mMapElement.tags.contains(Parameters.SIMPLIFICATION_EXCEPTIONS))
return TopologyPreservingSimplifier.simplify(geometry, Parameters.SIMPLIFICATION_TOLERANCE * 10);
}
return geometry;
}
}

2
vtm/src/org/oscim/utils/Parameters.java
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@ -85,7 +85,7 @@ public final class Parameters {
public static final Set<Tag> SIMPLIFICATION_EXCEPTIONS = new HashSet<>();
/**
* Reduce points on-the-fly while reading from map files.
* Reduce points on-the-fly while reading from vector maps.
* e.g. 0 (no simplification), 2, 4, ...
*/
public static int SIMPLIFICATION_TOLERANCE = 0;