This is an automated email from the ASF dual-hosted git repository.
desruisseaux pushed a commit to branch geoapi-4.0
in repository https://gitbox.apache.org/repos/asf/sis.git
commit 73b14d275fcaa9489f112214d96f45617af5cb64
Author: Martin Desruisseaux <martin.desruisse...@geomatys.com>
AuthorDate: Fri May 3 12:32:03 2024 +0200
Add explanation about the differences compared to published article.
Fix two wrong `@since` tags: put a placeholder for not-yet-determined
release.
---
.../iso/identification/AbstractIdentification.java | 4 ++--
.../referencing/operation/projection/Robinson.java | 20 ++++++++++++++++++--
2 files changed, 20 insertions(+), 4 deletions(-)
diff --git
a/endorsed/src/org.apache.sis.metadata/main/org/apache/sis/metadata/iso/identification/AbstractIdentification.java
b/endorsed/src/org.apache.sis.metadata/main/org/apache/sis/metadata/iso/identification/AbstractIdentification.java
index a301d3d51e..8fde87b8ed 100644
---
a/endorsed/src/org.apache.sis.metadata/main/org/apache/sis/metadata/iso/identification/AbstractIdentification.java
+++
b/endorsed/src/org.apache.sis.metadata/main/org/apache/sis/metadata/iso/identification/AbstractIdentification.java
@@ -520,7 +520,7 @@ public class AbstractIdentification extends ISOMetadata
implements Identificatio
*
* @return smallest resolvable temporal period in a resource.
*
- * @since 0.5
+ * @since 2.0
*/
@Override
// @XmlElement at the end of this class.
@@ -533,7 +533,7 @@ public class AbstractIdentification extends ISOMetadata
implements Identificatio
*
* @param newValues the new temporal resolutions.
*
- * @since 0.5
+ * @since 2.0
*/
public void setTemporalResolutions(final Collection<? extends Duration>
newValues) {
temporalResolutions = writeCollection(newValues, temporalResolutions,
Duration.class);
diff --git
a/endorsed/src/org.apache.sis.referencing/main/org/apache/sis/referencing/operation/projection/Robinson.java
b/endorsed/src/org.apache.sis.referencing/main/org/apache/sis/referencing/operation/projection/Robinson.java
index 4d51ebd276..5b64f8eb48 100644
---
a/endorsed/src/org.apache.sis.referencing/main/org/apache/sis/referencing/operation/projection/Robinson.java
+++
b/endorsed/src/org.apache.sis.referencing/main/org/apache/sis/referencing/operation/projection/Robinson.java
@@ -38,15 +38,25 @@ import static
org.apache.sis.referencing.operation.provider.Robinson.*;
* by interpolations of tabulated values instead of analytic function.
* The table is indexed by latitude at a constant interval.
*
- * <p>While the current implementation supports only the Robinson projection,
+ * <h2>Note on possible code reuse</h2>
+ * While the current implementation supports only the Robinson projection,
* it could be generalized to any projection using interpolations in a similar
way.
* For example, the "Natural Earth" projection was initially defined by
interpolations.
- * See {@link Variant} for a note about how to generalize.</p>
+ * See {@link Variant} for a note about how to generalize.
*
* <h2>References</h2>
* <p>Snyder, J. P. (1990). <u>The Robinson projection: A computation
algorithm.</u>
* Cartography and Geographic Information Systems, 17 (4), p. 301-305.</p>
*
+ * <h3>Changes compared to the reference</h3>
+ * The Snyder's article gives a program in the ANSI Fortran language. That
program has been translated
+ * to Java in this class and adapted for SIS architecture (constants moved to
normalization matrices).
+ * Robinson did not specify a particular interpolation method, but Snyder's
program uses the Stirling's
+ * central-difference formula, while PROJ uses cubic splices. Some other
software use Aitken interpolation.
+ * The Fortran program translated to Java did not converged well for the
inverse projection of points near
+ * a pole (maybe it is the reason why PROJ uses cubic splines instead). We
modified the algorithm with the
+ * use of derivative (∂y/∂φ) for faster convergence.
+ *
* @author Martin Desruisseaux (Geomatys)
*
* @see <a href="https://en.wikipedia.org/wiki/Robinson_projection";>Robinson
projection on Wikipedia</a>
@@ -167,6 +177,9 @@ public class Robinson extends NormalizedProjection {
* The units of measurement are implementation-specific (see super-class
javadoc).
* The results must be multiplied by the denormalization matrix before to
get linear distances.
*
+ * <p>Robinson did not specify a particular interpolation method. This
class uses the
+ * Stirling's central-difference formula as published in Snyder (1990)
article.</p>
+ *
* @return the matrix of the projection derivative at the given source
position,
* or {@code null} if the {@code derivate} argument is {@code
false}.
* @throws ProjectionException if the coordinates cannot be converted.
@@ -209,6 +222,9 @@ public class Robinson extends NormalizedProjection {
/**
* Converts the specified (<var>x</var>,<var>y</var>) coordinates
* and stores the result in {@code dstPts} (angles in radians).
+ *
+ * <p>Snyder's algorithm has been modified in this method with the use of
derivative (∂y/∂φ)
+ * for faster convergence. It is particularly important for points near
the poles.</p>
*/
@Override
protected void inverseTransform(final double[] srcPts, final int srcOff,
