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desruisseaux pushed a commit to branch geoapi-4.0
in repository https://gitbox.apache.org/repos/asf/sis.git
The following commit(s) were added to refs/heads/geoapi-4.0 by this push:
new c50df4d Provides a default accuracy value when no accuracy is
explicitly given in a NTv2 file. https://issues.apache.org/jira/browse/SIS-432
c50df4d is described below
commit c50df4d283ff23c7f9ad907b7452ecfeba7da8be
Author: Martin Desruisseaux <[email protected]>
AuthorDate: Sat Oct 13 23:15:37 2018 +0200
Provides a default accuracy value when no accuracy is explicitly given in a
NTv2 file.
https://issues.apache.org/jira/browse/SIS-432
---
.../referencing/provider/DatumShiftGridFile.java | 6 ++--
.../provider/FranceGeocentricInterpolation.java | 2 +-
.../sis/internal/referencing/provider/NTv2.java | 39 +++++++++++++++++-----
.../operation/builder/LocalizationGridBuilder.java | 14 +++++---
.../operation/builder/ResidualGrid.java | 4 ++-
5 files changed, 48 insertions(+), 17 deletions(-)
diff --git
a/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/DatumShiftGridFile.java
b/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/DatumShiftGridFile.java
index 7cc2603..cf1439d 100644
---
a/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/DatumShiftGridFile.java
+++
b/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/DatumShiftGridFile.java
@@ -104,6 +104,7 @@ public abstract class DatumShiftGridFile<C extends
Quantity<C>, T extends Quanti
/**
* The best translation accuracy that we can expect from this file.
+ * The unit of measurement depends on {@link #isCellValueRatio()}.
*
* <p>This field is initialized to {@link Double#NaN}. It is loader
responsibility
* to assign a value to this field after {@code DatumShiftGridFile}
construction.</p>
@@ -235,13 +236,14 @@ public abstract class DatumShiftGridFile<C extends
Quantity<C>, T extends Quanti
/**
* Suggests a precision for the translation values in this grid.
- * The default implementation returns a value smaller than the accuracy.
+ * This information is used for deciding when to stop iterations in
inverse transformations.
+ * The default implementation returns the {@linkplain #accuracy} divided
by an arbitrary value.
*
* @return a precision for the translation values in this grid.
*/
@Override
public double getCellPrecision() {
- return accuracy / 10; // Division by 10 is arbitrary.
+ return accuracy / 10; // Division by 10 is arbitrary.
}
/**
diff --git
a/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/FranceGeocentricInterpolation.java
b/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/FranceGeocentricInterpolation.java
index 7f7d8f3..347c78e 100644
---
a/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/FranceGeocentricInterpolation.java
+++
b/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/FranceGeocentricInterpolation.java
@@ -475,7 +475,7 @@ public class FranceGeocentricInterpolation extends
GeodeticOperation {
tX[p] = -parseFloat(t.nextToken()); // See javadoc for the
reason why we reverse the sign.
tY[p] = -parseFloat(t.nextToken());
tZ[p] = -parseFloat(t.nextToken());
- final double accuracy = ACCURACY[Math.min(ACCURACY.length-1,
+ final double accuracy = ACCURACY[Math.min(ACCURACY.length - 1,
Math.max(0, Integer.parseInt(t.nextToken()) - 1))];
if (!(accuracy >= grid.accuracy)) { // Use '!' for replacing
the initial NaN.
grid.accuracy = accuracy;
diff --git
a/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/NTv2.java
b/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/NTv2.java
index e87f2fc..baf0c4c 100644
---
a/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/NTv2.java
+++
b/core/sis-referencing/src/main/java/org/apache/sis/internal/referencing/provider/NTv2.java
@@ -60,7 +60,7 @@ import org.apache.sis.measure.Units;
*
* @author Simon Reynard (Geomatys)
* @author Martin Desruisseaux (Geomatys)
- * @version 0.8
+ * @version 1.0
* @since 0.7
* @module
*/
@@ -277,7 +277,8 @@ public final class NTv2 extends AbstractProvider {
* Current SIS implementation does not yet handle the above-cited
hierarchy of grids.
* For now we just take the first one.
*
- * <p>NTv2 grids contain also information about shifts accuracy. This
is not yet handled by SIS.</p>
+ * <p>NTv2 grids contain also information about shifts accuracy. This
is not yet handled by SIS,
+ * except for determining an approximate grid cell resolution.</p>
*/
final DatumShiftGridFile<Angle,Angle> readGrid() throws IOException,
FactoryException, NoninvertibleTransformException {
if (--remainingGrids < 0) {
@@ -321,12 +322,12 @@ public final class NTv2 extends AbstractProvider {
throw new
FactoryException(Errors.format(Errors.Keys.UnexpectedValueInElement_2,
"GS_COUNT", declared));
}
/*
- * Construct the grid with the sign of longitude values reversed,
in order to have longitude values
- * increasing toward East. We set isCellValueRatio = true (by the
arguments given to the constructor)
- * because this is required by our InterpolatedTransform
implementation. This setting implies that we
- * divide translation values by dx or dy at reading time. Note
that this free us from reversing the
- * sign of longitude translations; instead, this reversal will be
handled by grid.coordinateToGrid
- * MathTransform and its inverse.
+ * Construct the grid. The sign of longitude translations will
need to be reversed in order to have
+ * longitudes increasing toward East. We set isCellValueRatio =
true (by the arguments given to the
+ * DatumShiftGridFile constructor) because this is required by
InterpolatedTransform implementation.
+ * This setting implies that we divide translation values by dx or
dy at reading time. Note that this
+ * free us from reversing the sign of longitude translations in
the code below; instead, this reversal
+ * will be handled by grid.coordinateToGrid MathTransform and its
inverse.
*/
final DatumShiftGridFile.Float<Angle,Angle> grid = new
DatumShiftGridFile.Float<>(2,
unit, unit, true, -xmin, ymin, -dx, dy, width, height,
PARAMETERS, file);
@@ -338,9 +339,29 @@ public final class NTv2 extends AbstractProvider {
tx[i] = (float) (buffer.getFloat() / dx);
final double accuracy = Math.min(buffer.getFloat() / dy,
buffer.getFloat() / dx);
if (accuracy > 0 && !(accuracy >= grid.accuracy)) { // Use
'!' for replacing the initial NaN.
- grid.accuracy = accuracy;
+ grid.accuracy = accuracy; //
Smallest non-zero accuracy.
}
}
+ /*
+ * We need an estimation of translation accuracy, in order to
decide when to stop iterations
+ * during inverse transformations. If we did not found that
information in the file, compute
+ * an arbitrary default accuracy derived from the variations found
in actual values.
+ */
+ if (Double.isNaN(grid.accuracy)) {
+ double txmin = Double.POSITIVE_INFINITY;
+ double txmax = Double.NEGATIVE_INFINITY;
+ double tymin = Double.POSITIVE_INFINITY;
+ double tymax = Double.NEGATIVE_INFINITY;
+ for (int i=Math.min(tx.length, ty.length); --i >= 0;) {
+ double x = tx[i];
+ double y = ty[i];
+ if (x < txmin) txmin = x;
+ if (x > txmax) txmax = x;
+ if (y < tymin) tymin = y;
+ if (y > tymax) tymax = y;
+ }
+ grid.accuracy = Math.min(txmax - txmin, tymax - tymin) / 1000;
+ }
header.keySet().retainAll(Arrays.asList(overviewKeys)); // Keep
only overview records.
return DatumShiftGridCompressed.compress(grid, null, precision /
Math.max(dx, dy));
}
diff --git
a/core/sis-referencing/src/main/java/org/apache/sis/referencing/operation/builder/LocalizationGridBuilder.java
b/core/sis-referencing/src/main/java/org/apache/sis/referencing/operation/builder/LocalizationGridBuilder.java
index 7fc6e80..6b15576 100644
---
a/core/sis-referencing/src/main/java/org/apache/sis/referencing/operation/builder/LocalizationGridBuilder.java
+++
b/core/sis-referencing/src/main/java/org/apache/sis/referencing/operation/builder/LocalizationGridBuilder.java
@@ -96,12 +96,17 @@ public class LocalizationGridBuilder extends
TransformBuilder {
/**
* The desired precision of inverse transformations in unit of source
coordinates, or 0 in unspecified.
- * If no {@link #sourceToGrid} transform has been specified, than this is
in unit of grid cell.
+ * If no {@link #sourceToGrid} transform has been specified, then this is
in unit of grid cells
+ * (i.e. a value of 1 is the size of one grid cell).
+ *
+ * @see #setDesiredPrecision(double)
*/
private double precision;
/**
- * Arbitrary default {@link #precision} value. May change in any future
SIS version.
+ * Arbitrary default {@link #precision} value, in unit of grid cells. Used
if no explicit inverse transform
+ * precision has been specified. The {@code sourceToGrid} transform shall
not be applied on this value.
+ * This default precision may change in any future SIS version.
*/
static final double DEFAULT_PRECISION = 1E-7;
@@ -246,7 +251,8 @@ public class LocalizationGridBuilder extends
TransformBuilder {
/**
* Sets the desired precision of <em>inverse</em> transformations, in
units of source coordinates.
* If a conversion from "real world" to grid coordinates {@linkplain
#setSourceToGrid has been specified},
- * then the given precision is in "real world" units. Otherwise the
precision is in units of grid cells.
+ * then the given precision is in "real world" units. Otherwise the
precision is in units of grid cells
+ * (i.e. a value of 1 is the size of one grid cell).
*
* <div class="note"><b>Note:</b>
* there is no method for setting the desired target precision because
forward transformations <em>precision</em>
@@ -433,7 +439,7 @@ public class LocalizationGridBuilder extends
TransformBuilder {
boolean isLinear = true;
for (final double c : linear.correlation()) {
isExact &= (c == 1);
- if (c < 0.9999) { // Empirical
threshold (may need to be revisited).
+ if (!(c >= 0.9999)) { // Empirical
threshold (may need to be revisited).
isLinear = false;
break;
}
diff --git
a/core/sis-referencing/src/main/java/org/apache/sis/referencing/operation/builder/ResidualGrid.java
b/core/sis-referencing/src/main/java/org/apache/sis/referencing/operation/builder/ResidualGrid.java
index f9e222b..7d99315 100644
---
a/core/sis-referencing/src/main/java/org/apache/sis/referencing/operation/builder/ResidualGrid.java
+++
b/core/sis-referencing/src/main/java/org/apache/sis/referencing/operation/builder/ResidualGrid.java
@@ -73,6 +73,7 @@ final class ResidualGrid extends
DatumShiftGridFile<Dimensionless,Dimensionless>
* @param gridToTarget conversion from grid coordinates to the final
"real world" coordinates.
* @param numDim number of dimension of target coordinates.
* @param residuals the residual data, as translations to apply on the
result of affine transform.
+ * @param precision desired precision of inverse transformations in
unit of grid cells.
*/
ResidualGrid(final LinearTransform sourceToGrid, final LinearTransform
gridToTarget,
final int nx, final int ny, final int numDim, final double[]
residuals, final double precision)
@@ -131,7 +132,8 @@ final class ResidualGrid extends
DatumShiftGridFile<Dimensionless,Dimensionless>
/**
* Returns the desired precision in iterative calculation performed by
inverse transform.
- * The returned value is in unit of grid cell.
+ * The returned value is in unit of grid cell, i.e. a value of 1 is the
size of one cell.
+ * This unit of measurement is fixed by {@link #isCellValueRatio()} =
{@code true}.
*/
@Override
public double getCellPrecision() {
