Mercator: Article example implementation of mercator projections.

core-java/src/main/java/com/baeldung/mercator/EllipticalMercator.java

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+package com.baeldung.mercator;
+
+class EllipticalMercator extends Mercator {
+    @Override
+    double yAxisProjection(double input) {
+        if (input > 89.5) {
+            input = 89.5;
+        }
+        if (input < -89.5) {
+            input = -89.5;
+        }
+        double temp = RADIUS_MINOR / RADIUS_MAJOR;
+        double es = 1.0 - (temp * temp);
+        double eccent = Math.sqrt(es);
+        double phi = Math.toRadians(input);
+        double sinphi = Math.sin(phi);
+        double con = eccent * sinphi;
+        double com = 0.5 * eccent;
+        con = Math.pow(((1.0 - con)/(1.0+con)), com);
+        double ts = Math.tan(0.5 * ((Math.PI*0.5) - phi))/con;
+        double y = 0 - RADIUS_MAJOR * Math.log(ts);
+        return y;
+    }
+
+    @Override
+    double xAxisProjection(double input) {
+        return RADIUS_MAJOR * Math.toRadians(input);
+    }
+}

core-java/src/main/java/com/baeldung/mercator/Mercator.java

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+package com.baeldung.mercator;
+
+abstract class Mercator {
+    final static double RADIUS_MAJOR = 6378137.0;
+    final static double RADIUS_MINOR = 6356752.3142;
+
+    abstract double yAxisProjection(double input);
+
+    abstract double xAxisProjection(double input);
+}

core-java/src/main/java/com/baeldung/mercator/SphericalMercator.java

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+package com.baeldung.mercator;
+
+public class SphericalMercator extends  Mercator {
+
+    @Override
+    double yAxisProjection(double input) {
+        return Math.toRadians(input) * RADIUS_MAJOR;
+    }
+
+    @Override
+    double xAxisProjection(double input) {
+        return Math.log(Math.tan(Math.PI / 4 + Math.toRadians(input) / 2)) * RADIUS_MAJOR;
+    }
+}

core-java/src/test/java/com/baeldung/mercator/EllipticalMercatorUnitTest.java

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+package com.baeldung.mercator;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.junit.MockitoJUnitRunner;
+
+import static junit.framework.TestCase.assertEquals;
+
+@RunWith(MockitoJUnitRunner.class)
+public class EllipticalMercatorUnitTest {
+
+    @Test
+    public void giventThatTheInputIs22_whenXAxisProjectionIsCalled_thenTheResultIsTheCorrectOne() {
+        Mercator mercator = new EllipticalMercator();
+        double result = mercator.xAxisProjection(22);
+        assertEquals(result, 2449028.7974520186);
+    }
+
+    @Test
+    public void giventThatTheInputIs44_whenYAxisProjectionIsCalled_thenTheResultIsTheCorrectOne() {
+        Mercator mercator = new EllipticalMercator();
+        double result = mercator.yAxisProjection(44);
+        assertEquals(result, 5435749.887511954);
+    }
+}

core-java/src/test/java/com/baeldung/mercator/SphericalMercatorUnitTest.java

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+package com.baeldung.mercator;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.junit.MockitoJUnitRunner;
+
+import static junit.framework.TestCase.assertEquals;
+
+@RunWith(MockitoJUnitRunner.class)
+public class SphericalMercatorUnitTest {
+
+    @Test
+    public void giventThatTheInputIs22_whenXAxisProjectionIsCalled_thenTheResultIsTheCorrectOne() {
+        Mercator mercator = new SphericalMercator();
+        double result = mercator.xAxisProjection(22);
+        assertEquals(result, 2511525.234845713);
+    }
+
+    @Test
+    public void giventThatTheInputIs44_whenYAxisProjectionIsCalled_thenTheResultIsTheCorrectOne() {
+        Mercator mercator = new SphericalMercator();
+        double result = mercator.yAxisProjection(44);
+        assertEquals(result, 4898057.594904037);
+    }
+}