From 0b2aea7144b45d4fc3c7a26c8b107b93ac670fbd Mon Sep 17 00:00:00 2001
From: Luc Maisonobe <luc@orekit.org>
Date: Wed, 10 Sep 2014 17:09:34 +0200
Subject: [PATCH] Fixed errors in basic scan algorithm.
Near tile boundaries, the algorithm sometime failed to find intersection
points.
---
.../intersection/BasicScanAlgorithm.java | 20 +++---
.../org/orekit/rugged/api/RuggedTest.java | 68 ++++++++++++++++++-
2 files changed, 76 insertions(+), 12 deletions(-)
diff --git a/core/src/main/java/org/orekit/rugged/intersection/BasicScanAlgorithm.java b/core/src/main/java/org/orekit/rugged/intersection/BasicScanAlgorithm.java
index 99e2cc4c..fca8fa28 100644
--- a/core/src/main/java/org/orekit/rugged/intersection/BasicScanAlgorithm.java
+++ b/core/src/main/java/org/orekit/rugged/intersection/BasicScanAlgorithm.java
@@ -87,7 +87,7 @@ public class BasicScanAlgorithm implements IntersectionAlgorithm {
exitPoint = ellipsoid.transform(ellipsoid.pointAtAltitude(position, los, Double.isInfinite(hMin) ? 0.0 : hMin),
ellipsoid.getBodyFrame(), null);
final SimpleTile exitTile = cache.getTile(exitPoint.getLatitude(), exitPoint.getLongitude());
- addIfNotPresent(scannedTiles, entryTile);
+ addIfNotPresent(scannedTiles, exitTile);
minLatitude = FastMath.min(entryPoint.getLatitude(), exitPoint.getLatitude());
maxLatitude = FastMath.max(entryPoint.getLatitude(), exitPoint.getLatitude());
@@ -116,7 +116,7 @@ public class BasicScanAlgorithm implements IntersectionAlgorithm {
for (final SimpleTile tile : scannedTiles) {
for (int i = latitudeIndex(tile, minLatitude); i <= latitudeIndex(tile, maxLatitude); ++i) {
for (int j = longitudeIndex(tile, minLongitude); j <= longitudeIndex(tile, maxLongitude); ++j) {
- GeodeticPoint gp = tile.pixelIntersection(entryPoint, ellipsoid.convertLos(entryPoint, los), i, j);
+ final GeodeticPoint gp = tile.pixelIntersection(entryPoint, ellipsoid.convertLos(entryPoint, los), i, j);
if (gp != null) {
// improve the point, by projecting it back on the 3D line, fixing the small body curvature at pixel level
@@ -124,13 +124,15 @@ public class BasicScanAlgorithm implements IntersectionAlgorithm {
final double s = Vector3D.dotProduct(delta, los) / los.getNormSq();
final GeodeticPoint projected = ellipsoid.transform(new Vector3D(1, position, s, los),
ellipsoid.getBodyFrame(), null);
- gp = tile.pixelIntersection(projected, ellipsoid.convertLos(projected, los), i, j);
-
- final Vector3D point = ellipsoid.transform(gp);
- final double dot = Vector3D.dotProduct(point.subtract(position), los);
- if (dot < intersectionDot) {
- intersectionGP = gp;
- intersectionDot = dot;
+ final GeodeticPoint gpImproved = tile.pixelIntersection(projected, ellipsoid.convertLos(projected, los), i, j);
+
+ if (gpImproved != null) {
+ final Vector3D point = ellipsoid.transform(gpImproved);
+ final double dot = Vector3D.dotProduct(point.subtract(position), los);
+ if (dot < intersectionDot) {
+ intersectionGP = gpImproved;
+ intersectionDot = dot;
+ }
}
}
diff --git a/core/src/test/java/org/orekit/rugged/api/RuggedTest.java b/core/src/test/java/org/orekit/rugged/api/RuggedTest.java
index 63bc4b18..8697873b 100644
--- a/core/src/test/java/org/orekit/rugged/api/RuggedTest.java
+++ b/core/src/test/java/org/orekit/rugged/api/RuggedTest.java
@@ -148,7 +148,7 @@ public class RuggedTest {
FastMath.toRadians(1.0), 1201);
Rugged rugged = new Rugged(updater, 8, AlgorithmId.DUVENHAGE,
- EllipsoidId.WGS84, InertialFrameId.EME2000, BodyRotatingFrameId.ITRF,
+ EllipsoidId.GRS80, InertialFrameId.EME2000, BodyRotatingFrameId.ITRF,
pv.get(0).getDate(), pv.get(pv.size() - 1).getDate(), 5.0,
pv, 8, CartesianDerivativesFilter.USE_PV, q, 8, AngularDerivativesFilter.USE_R, 0.001);
@@ -178,7 +178,7 @@ public class RuggedTest {
FastMath.toRadians(1.0), 1201);
Rugged rugged = new Rugged(updater, 8, AlgorithmId.DUVENHAGE,
- EllipsoidId.WGS84, InertialFrameId.EME2000, BodyRotatingFrameId.ITRF,
+ EllipsoidId.IERS96, InertialFrameId.EME2000, BodyRotatingFrameId.ITRF,
orbit.getDate().shiftedBy(-10.0), orbit.getDate().shiftedBy(+10.0), 5.0,
1.0, 8, CartesianDerivativesFilter.USE_PV, AngularDerivativesFilter.USE_R, 0.001, propagator);
@@ -392,7 +392,7 @@ public class RuggedTest {
AbsoluteDate maxDate = lineSensor.getDate(lastLine);
Rugged rugged = new Rugged(null, -1, AlgorithmId.IGNORE_DEM_USE_ELLIPSOID,
- EllipsoidId.WGS84, InertialFrameId.EME2000, BodyRotatingFrameId.ITRF,
+ EllipsoidId.IERS2003, InertialFrameId.EME2000, BodyRotatingFrameId.ITRF,
minDate, maxDate, 5.0,
orbitToPV(orbit, earth, minDate.shiftedBy(-1.0), maxDate.shiftedBy(+1.0), 0.25), 8,
CartesianDerivativesFilter.USE_PV,
@@ -538,6 +538,68 @@ public class RuggedTest {
}
+ @Test
+ public void testBasicScan()
+ throws RuggedException, OrekitException, URISyntaxException {
+
+ int dimension = 200;
+
+ String path = getClass().getClassLoader().getResource("orekit-data").toURI().getPath();
+ DataProvidersManager.getInstance().addProvider(new DirectoryCrawler(new File(path)));
+ final BodyShape earth = createEarth();
+ final Orbit orbit = createOrbit(Constants.EIGEN5C_EARTH_MU);
+
+ AbsoluteDate crossing = new AbsoluteDate("2012-01-01T12:30:00.000", TimeScalesFactory.getUTC());
+
+ // one line sensor
+ // position: 1.5m in front (+X) and 20 cm above (-Z) of the S/C center of mass
+ // los: swath in the (YZ) plane, looking at 50° roll, ±1° aperture
+ Vector3D position = new Vector3D(1.5, 0, -0.2);
+ List<Vector3D> los = createLOS(new Rotation(Vector3D.PLUS_I, FastMath.toRadians(50.0)).applyTo(Vector3D.PLUS_K),
+ Vector3D.PLUS_I,
+ FastMath.toRadians(1.0), dimension);
+
+ // linear datation model: at reference time we get line 100, and the rate is one line every 1.5ms
+ LineDatation lineDatation = new LinearLineDatation(crossing, dimension / 2, 1.0 / 1.5e-3);
+ int firstLine = 0;
+ int lastLine = dimension;
+ LineSensor lineSensor = new LineSensor("line", lineDatation, position, los);
+ AbsoluteDate minDate = lineSensor.getDate(firstLine);
+ AbsoluteDate maxDate = lineSensor.getDate(lastLine);
+
+ TileUpdater updater =
+ new RandomLandscapeUpdater(0.0, 9000.0, 0.5, 0xe12ef744f224cf43l,
+ FastMath.toRadians(1.0), 257);
+
+ Rugged ruggedDuvenhage = new Rugged(updater, 8, AlgorithmId.DUVENHAGE,
+ EllipsoidId.WGS84, InertialFrameId.EME2000, BodyRotatingFrameId.ITRF,
+ minDate, maxDate, 5.0,
+ orbitToPV(orbit, earth, minDate.shiftedBy(-1.0), maxDate.shiftedBy(+1.0), 0.25), 8,
+ CartesianDerivativesFilter.USE_PV,
+ orbitToQ(orbit, earth, minDate.shiftedBy(-1.0), maxDate.shiftedBy(+1.0), 0.25), 2,
+ AngularDerivativesFilter.USE_R, 0.001);
+ ruggedDuvenhage.addLineSensor(lineSensor);
+ GeodeticPoint[] gpDuvenhage = ruggedDuvenhage.directLocalization("line", 100);
+
+ Rugged ruggedBasicScan = new Rugged(updater, 8, AlgorithmId.BASIC_SLOW_EXHAUSTIVE_SCAN_FOR_TESTS_ONLY,
+ EllipsoidId.WGS84, InertialFrameId.EME2000, BodyRotatingFrameId.ITRF,
+ minDate, maxDate, 5.0,
+ orbitToPV(orbit, earth, minDate.shiftedBy(-1.0), maxDate.shiftedBy(+1.0), 0.25), 8,
+ CartesianDerivativesFilter.USE_PV,
+ orbitToQ(orbit, earth, minDate.shiftedBy(-1.0), maxDate.shiftedBy(+1.0), 0.25), 2,
+ AngularDerivativesFilter.USE_R, 0.001);
+ ruggedBasicScan.addLineSensor(lineSensor);
+ GeodeticPoint[] gpBasicScan = ruggedBasicScan.directLocalization("line", 100);
+
+
+ for (int i = 0; i < gpDuvenhage.length; ++i) {
+ Vector3D pDuvenhage = earth.transform(gpDuvenhage[i]);
+ Vector3D pBasicScan = earth.transform(gpBasicScan[i]);
+ Assert.assertEquals(0.0, Vector3D.distance(pDuvenhage, pBasicScan), 4.0e-5);
+ }
+
+ }
+
@Test
public void testInterpolatorDump()
throws RuggedException, OrekitException, URISyntaxException {
--
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