From 3aae8e8675f476a9c10a6ba4126c0923ffba9b8b Mon Sep 17 00:00:00 2001
From: Luc Maisonobe <luc@orekit.org>
Date: Mon, 5 May 2014 15:36:47 +0200
Subject: [PATCH] Ensure sensor mean plane normal has a deterministic
orientation.
---
.../java/org/orekit/rugged/core/Sensor.java | 20 +++++++++++++++----
.../org/orekit/rugged/core/SensorTest.java | 8 ++++----
2 files changed, 20 insertions(+), 8 deletions(-)
diff --git a/src/main/java/org/orekit/rugged/core/Sensor.java b/src/main/java/org/orekit/rugged/core/Sensor.java
index 05c75779..56062e2c 100644
--- a/src/main/java/org/orekit/rugged/core/Sensor.java
+++ b/src/main/java/org/orekit/rugged/core/Sensor.java
@@ -114,7 +114,14 @@ public class Sensor {
// extract the left singular vector corresponding to least singular value
// (i.e. last vector since Apache Commons Math returns the values
// in non-increasing order)
- normal = new Vector3D(svd.getU().getColumn(2)).normalize();
+ final Vector3D singularVector = new Vector3D(svd.getU().getColumn(2)).normalize();
+
+ // check rotation order
+ if (Vector3D.dotProduct(singularVector, Vector3D.crossProduct(los.get(0), los.get(los.size() - 1))) >= 0) {
+ normal = singularVector;
+ } else {
+ normal = singularVector.negate();
+ }
}
@@ -165,16 +172,21 @@ public class Sensor {
}
/** Get the mean plane normal.
+ * <p>
+ * The normal is oriented such traversing pixels in increasing indices
+ * order corresponds is consistent with trigonometric order (i.e.
+ * counterclockwise).
+ * </p>
* @return mean plane normal
*/
public Vector3D getMeanPlaneNormal() {
return normal;
}
- /** Get the mean plane reference point.
- * @return mean plane reference point
+ /** Get the sensor reference point.
+ * @return reference point
*/
- public Vector3D getMeanPlaneReferencePoint() {
+ public Vector3D getReferencePoint() {
return referencePoint;
}
diff --git a/src/test/java/org/orekit/rugged/core/SensorTest.java b/src/test/java/org/orekit/rugged/core/SensorTest.java
index 748aedbb..2d22421a 100644
--- a/src/test/java/org/orekit/rugged/core/SensorTest.java
+++ b/src/test/java/org/orekit/rugged/core/SensorTest.java
@@ -52,8 +52,8 @@ public class SensorTest {
Assert.assertEquals("perfect line", sensor.getName());
Assert.assertEquals(AbsoluteDate.J2000_EPOCH, sensor.getDate(0.0));
- Assert.assertEquals(0.0, Vector3D.dotProduct(normal, center.subtract(sensor.getMeanPlaneReferencePoint())), 1.0e-15);
- Assert.assertEquals(0.0, FastMath.sin(Vector3D.angle(normal, sensor.getMeanPlaneNormal())), 1.0e-15);
+ Assert.assertEquals(0.0, Vector3D.dotProduct(normal, center.subtract(sensor.getReferencePoint())), 1.0e-15);
+ Assert.assertEquals(0.0, Vector3D.angle(normal, sensor.getMeanPlaneNormal()), 1.0e-15);
}
@@ -85,8 +85,8 @@ public class SensorTest {
Assert.assertEquals("noisy line", sensor.getName());
Assert.assertEquals(AbsoluteDate.J2000_EPOCH, sensor.getDate(0.0));
- Assert.assertEquals(0.0, Vector3D.dotProduct(normal, center.subtract(sensor.getMeanPlaneReferencePoint())), 1.0e-5);
- Assert.assertEquals(0.0, FastMath.sin(Vector3D.angle(normal, sensor.getMeanPlaneNormal())), 3.0e-7);
+ Assert.assertEquals(0.0, Vector3D.dotProduct(normal, center.subtract(sensor.getReferencePoint())), 1.0e-5);
+ Assert.assertEquals(0.0, Vector3D.angle(normal, sensor.getMeanPlaneNormal()), 3.0e-7);
}
--
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