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desruisseaux pushed a commit to branch geoapi-4.0
in repository https://gitbox.apache.org/repos/asf/sis.git
commit b677477aec0b6aba473ec838709ad4092b276312
Author: Martin Desruisseaux <martin.desruisse...@geomatys.com>
AuthorDate: Sat Jan 29 16:02:27 2022 +0100
Add tests for north pole rotation.
---
.../referencing/provider/RotatedNorthPole.java | 5 +
.../referencing/provider/RotatedSouthPole.java | 4 +
.../operation/transform/RotatedPole.java | 9 +-
.../operation/transform/RotatedPoleTest.java | 115 ++++++++++++++++++++-
4 files changed, 126 insertions(+), 7 deletions(-)
diff --git
a/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/RotatedNorthPole.java
b/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/RotatedNorthPole.java
index e338bea..ba921ad 100644
---
a/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/RotatedNorthPole.java
+++
b/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/RotatedNorthPole.java
@@ -37,6 +37,11 @@ import org.apache.sis.measure.Units;
* This is similar to the WMO Rotated Latitude/Longitude but rotating north
pole instead of
* south pole.
*
+ * <h2>Comparison with UCAR library</h2>
+ * {@link ucar.unidata.geoloc.projection.RotatedPole} in UCAR netCDF library
version 5.5.2
+ * gives results with an offset of 180° in longitude values compared to our
implementation.
+ * See {@code RotatedPoleTest.testRotateNorthPoleOnGreenwich()} for more
details.
+ *
* @author Martin Desruisseaux (Geomatys)
* @version 1.2
*
diff --git
a/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/RotatedSouthPole.java
b/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/RotatedSouthPole.java
index b485905..2f18264 100644
---
a/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/RotatedSouthPole.java
+++
b/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/RotatedSouthPole.java
@@ -36,6 +36,10 @@ import org.apache.sis.measure.Units;
* The provider for the WMO <cite>Rotated Latitude/Longitude</cite> coordinate
operation.
* This is defined by the World Meteorological Organization (WMO) in GRIB2
template 3.1.
*
+ * <h2>Comparison with UCAR library</h2>
+ * This is consistent with {@link ucar.unidata.geoloc.projection.RotatedLatLon}
+ * in UCAR netCDF library version 5.5.2.
+ *
* @author Martin Desruisseaux (Geomatys)
* @version 1.2
* @since 1.2
diff --git
a/core/sis-referencing/src/main/java/org/apache/sis/referencing/operation/transform/RotatedPole.java
b/core/sis-referencing/src/main/java/org/apache/sis/referencing/operation/transform/RotatedPole.java
index 6e613fd..513d4cd 100644
---
a/core/sis-referencing/src/main/java/org/apache/sis/referencing/operation/transform/RotatedPole.java
+++
b/core/sis-referencing/src/main/java/org/apache/sis/referencing/operation/transform/RotatedPole.java
@@ -153,7 +153,9 @@ public class RotatedPole extends AbstractMathTransform2D
implements Serializable
i = 3 - i;
}
double value = -((Number) ((ParameterValue<?>)
values.get(i)).getValue()).doubleValue();
- if (i == 0) value = IEEEremainder(value + 180, 360);
+ if (i == 0 &&
RotatedSouthPole.PARAMETERS.equals(forward.getDescriptor())) {
+ value = IEEEremainder(value + 180, 360);
+ }
target.setValue(value);
return true;
}
@@ -340,8 +342,9 @@ public class RotatedPole extends AbstractMathTransform2D
implements Serializable
public boolean isIdentity() {
return sinφp == -1;
/*
- * We do not test `cosφp` because that value may be small but
non-zero, especially since there is no exact
- * representation of `cos(π/2)`. Testing `sinφp == -1` is a way to
allow for a small tolerance around π/2.
+ * We do not test `cosφp` because that value can be small but not
zero, because
+ * there is no way to compute exactly `cos(π/2)` with `Math.PI`
approximation.
+ * Testing `sinφp == -1` is a way to allow for a small tolerance
around π/2.
* This policy is also needed for consistency with
`RotatedPole(RotatedPole)` implementation.
*/
}
diff --git
a/core/sis-referencing/src/test/java/org/apache/sis/referencing/operation/transform/RotatedPoleTest.java
b/core/sis-referencing/src/test/java/org/apache/sis/referencing/operation/transform/RotatedPoleTest.java
index 6764670..7072333 100644
---
a/core/sis-referencing/src/test/java/org/apache/sis/referencing/operation/transform/RotatedPoleTest.java
+++
b/core/sis-referencing/src/test/java/org/apache/sis/referencing/operation/transform/RotatedPoleTest.java
@@ -59,9 +59,22 @@ public final strictfp class RotatedPoleTest extends
MathTransformTestCase {
}
/**
+ * Creates a new transform which should be the inverse of current
transform according
+ * the parameters declared in {@link RotatedPole#context}. This is the
same work than
+ * {@link #inverseSouthPoleTransform()} but for the other transform.
+ */
+ private void inverseNorthPoleTransform() throws FactoryException,
TransformException {
+ final ParameterValueGroup pg = ((Parameterized)
transform.inverse()).getParameterValues();
+ transform = RotatedPole.rotateSouthPole(factory(),
+ pg.parameter("grid_north_pole_latitude") .doubleValue(),
+ pg.parameter("grid_north_pole_longitude").doubleValue(),
+ pg.parameter("north_pole_grid_longitude").doubleValue());
+ }
+
+ /**
* Tests a rotation of south pole with the new pole on Greenwich.
- * The {@link ucar.unidata.geoloc.LatLonPoint} class has been used
- * as a reference implementation for computing the expected values.
+ * The {@link ucar.unidata.geoloc.projection.RotatedLatLon} class
+ * has been used as a reference implementation for expected values.
*
* @throws FactoryException if the transform can not be created.
* @throws TransformException if an error occurred while transforming a
point.
@@ -88,8 +101,8 @@ public final strictfp class RotatedPoleTest extends
MathTransformTestCase {
/**
* Tests a rotation of south pole with the pole on arbitrary meridian.
- * The {@link ucar.unidata.geoloc.LatLonPoint} class has been used as
- * a reference implementation for computing the expected values.
+ * The {@link ucar.unidata.geoloc.projection.RotatedLatLon} class has
+ * been used as a reference implementation for expected values.
*
* @throws FactoryException if the transform can not be created.
* @throws TransformException if an error occurred while transforming a
point.
@@ -114,4 +127,98 @@ public final strictfp class RotatedPoleTest extends
MathTransformTestCase {
inverseSouthPoleTransform();
verifyTransform(expected, coordinates);
}
+
+ /**
+ * Tries rotating a pole to opposite hemisphere.
+ *
+ * @throws FactoryException if the transform can not be created.
+ * @throws TransformException if an error occurred while transforming a
point.
+ */
+ @Test
+ public void testRotateToOppositeHemisphere() throws FactoryException,
TransformException {
+ transform = RotatedPole.rotateSouthPole(factory(), 50, 20, 10);
+ tolerance = Formulas.ANGULAR_TOLERANCE;
+ isDerivativeSupported = false;
+ final double[] coordinates = { // (λ,φ) coordinates to convert.
+ 20, 51,
+ 80, 44,
+ -30, 89
+ };
+ final double[] expected = { // (λ,φ) coordinates after
conversion.
+ -10.000000000, -89.000000000,
+ 64.651211252, -49.758697265,
+ -11.207848626, -50.636582758
+ };
+ verifyTransform(coordinates, expected);
+ inverseSouthPoleTransform();
+ verifyTransform(expected, coordinates);
+ }
+
+ /**
+ * Tests a rotation of north pole with the new pole on Greenwich.
+ *
+ * <h4>Comparison with UCAR library</h4>
+ * {@link ucar.unidata.geoloc.projection.RotatedPole} in UCAR netCDF
library version 5.5.2
+ * gives results with an offset of 180° in longitude values compared to
our implementation.
+ * But geometrical reasoning suggests that our implementation is correct:
if we rotate the
+ * pole to 60°N, then latitude of 54°N on Greenwich meridian become only
6° below new pole,
+ * i.e. 84°N but still on the same meridian (Greenwich) because we did not
cross the pole.
+ *
+ * @throws FactoryException if the transform can not be created.
+ * @throws TransformException if an error occurred while transforming a
point.
+ */
+ @Test
+ public void testRotateNorthPoleOnGreenwich() throws FactoryException,
TransformException {
+ transform = RotatedPole.rotateNorthPole(factory(), 60, 0, 0);
+ tolerance = Formulas.ANGULAR_TOLERANCE;
+ isDerivativeSupported = false;
+ final double[] coordinates = { // (λ,φ) coordinates to convert.
+ 0, 54,
+ 20, 62,
+ -30, 89
+ };
+ final double[] expected = { // (λ,φ) coordinates after
conversion.
+ 0.000000000, 84.000000000,
+ 110.307140436, 80.141810970,
+ -178.973119126, 60.862133738
+ };
+ verifyTransform(coordinates, expected);
+ inverseNorthPoleTransform();
+ verifyTransform(expected, coordinates);
+ }
+
+ /**
+ * Tests a rotation of north pole with the pole on arbitrary meridian.
+ * Result can be compared with PROJ using the following command, where
+ * {@code coords.txt} is a file containing input coordinates in (λ,φ)
+ * order and the output is in (φ,λ) order.
+ *
+ * {@preformat shell
+ * cs2cs -I -E -f %g "EPSG:4326" +to +type=crs +proj=ob_tran
+o_proj=longlat +datum=WGS84 +no_defs \
+ * +o_lat_p=70 +o_lon_p=40 +lon_0=0 coords.txt
+ * }
+ *
+ * @throws FactoryException if the transform can not be created.
+ * @throws TransformException if an error occurred while transforming a
point.
+ */
+ @Test
+ @DependsOnMethod("testRotateNorthPoleOnGreenwich")
+ public void testRotateNorthPole() throws FactoryException,
TransformException {
+ transform = RotatedPole.rotateNorthPole(factory(), 70, 40, 0);
+ tolerance = Formulas.ANGULAR_TOLERANCE;
+ isDerivativeSupported = false;
+ final double[] coordinates = { // (λ,φ) coordinates to convert.
+ 0, 54,
+ 20, 62,
+ -30, 89
+ };
+ final double[] expected = { // (λ,φ) coordinates after
conversion.
+ -68.817428350, 66.096411904,
+ -54.967324181, 78.691210976,
+ -177.208632734, 70.320491507
+ };
+ verifyTransform(coordinates, expected);
+ inverseNorthPoleTransform();
+ verifyTransform(expected, coordinates);
+ }
}
