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Fix Antarctica landcover #342

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merged 3 commits into from
Jan 5, 2025
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Fix Antarctica landcover #342

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e7de595
Fix Antarctica landcover
wipfli Jan 4, 2025
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wipfli Jan 4, 2025
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wipfli Jan 4, 2025
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18 changes: 18 additions & 0 deletions tiles/src/main/java/com/protomaps/basemap/layers/Earth.java
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@
import com.protomaps.basemap.feature.FeatureId;
import com.protomaps.basemap.names.OsmNames;
import java.util.List;
import org.locationtech.jts.geom.Point;

public class Earth implements ForwardingProfile.LayerPostProcesser {
@Override
Expand All @@ -29,6 +30,23 @@ public void processNe(SourceFeature sf, FeatureCollector features) {
} else if (sourceLayer.equals("ne_10m_land")) {
features.polygon(this.name()).setZoomRange(5, 5).setBufferPixels(8).setAttr("kind", "earth");
}
// Daylight landcover uses ESA WorldCover which only goes to a latitude of roughly 80 deg S.
// Parts of Antarctica therefore get no landcover = glacier from Daylight.
// To fix this, we add glaciated areas from Natural Earth in Antarctica.
if (sourceLayer.equals("ne_10m_glaciated_areas")) {
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This section deserves a comment explaining the problem and why this particular solution works

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Added one, thanks for the tip!

try {
Point centroid = (Point) sf.centroid();
// Web Mercator Y = 0.7 is roughly 60 deg South, i.e., Antarctica.
if (centroid.getY() > 0.7) {
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This works, but it's confusing this isn't a negative number, and 70 would normally not result in the northern tip of Chilean Antarctica (many international bases there) showing up correctly as ice.

Please add a comment explaining that you're targeting ice features in Antarctica south of -60°.

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Web Mercator Y in Planetiler goes from 0 to 1 from 85 deg N to 85 deg S. The equator is at Web Mercator Y = 0.5

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Added the comment

features.polygon("landcover")
.setAttr("kind", "glacier")
.setZoomRange(0, 7)
.setMinPixelSize(0.0);
}
} catch (GeometryException e) {
System.out.println("Error: " + e);
}
}
}

public void processOsm(SourceFeature sf, FeatureCollector features) {
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