From 7285fb6fc0ae106b13bbce51f7368352f47494cf Mon Sep 17 00:00:00 2001
From: Luc Maisonobe <luc@orekit.org>
Date: Fri, 2 May 2014 21:39:43 +0200
Subject: [PATCH] Added a flat-body implementation of refineIntersection.
The former implementation ignored the flat-body flag and in fact
corrected the flat-body ...
---
.../core/duvenhage/DuvenhageAlgorithm.java | 32 +++++++++++++------
1 file changed, 22 insertions(+), 10 deletions(-)
diff --git a/src/main/java/org/orekit/rugged/core/duvenhage/DuvenhageAlgorithm.java b/src/main/java/org/orekit/rugged/core/duvenhage/DuvenhageAlgorithm.java
index 04d19d55..e128456f 100644
--- a/src/main/java/org/orekit/rugged/core/duvenhage/DuvenhageAlgorithm.java
+++ b/src/main/java/org/orekit/rugged/core/duvenhage/DuvenhageAlgorithm.java
@@ -54,8 +54,8 @@ public class DuvenhageAlgorithm implements IntersectionAlgorithm {
* from entry/exit points in the DEM are considered to be straight lines also
* in geodetic coordinates. The sagitta resulting from real ellipsoid curvature
* is therefore <em>not</em> corrected in this case. As this computation is not
- * costly (a few percents overhead), it is not recommended to set this parameter
- * to {@code true}. This flag is mainly intended for comparison purposes with other systems.
+ * costly (a few percents overhead), it is highly recommended to set this parameter
+ * to {@code false}. This flag is mainly intended for comparison purposes with other systems.
*/
public DuvenhageAlgorithm(final TileUpdater updater, final int maxCachedTiles,
final boolean flatBody) {
@@ -152,14 +152,26 @@ public class DuvenhageAlgorithm implements IntersectionAlgorithm {
final GeodeticPoint closeGuess)
throws RuggedException {
try {
- final Vector3D delta = ellipsoid.transform(closeGuess).subtract(position);
- final double s = Vector3D.dotProduct(delta, los) / los.getNormSq();
- final GeodeticPoint projected = ellipsoid.transform(new Vector3D(1, position, s, los),
- ellipsoid.getBodyFrame(), null);
- final Tile tile = cache.getTile(projected.getLatitude(), projected.getLongitude());
- return tile.pixelIntersection(projected, ellipsoid.convertLos(projected, los),
- tile.getLatitudeIndex(projected.getLatitude()),
- tile.getLongitudeIndex(projected.getLongitude()));
+ if (flatBody) {
+ // under the (bad) flat-body assumption, the reference point must remain
+ // at DEM entry, even if we already have a much better close guess :-(
+ // this is in order to remain consistent with other systems
+ final Tile tile = cache.getTile(closeGuess.getLatitude(), closeGuess.getLongitude());
+ final Vector3D entryP = ellipsoid.pointAtAltitude(position, los, tile.getMaxElevation());
+ final GeodeticPoint entry = ellipsoid.transform(entryP, ellipsoid.getBodyFrame(), null);
+ return tile.pixelIntersection(entry, ellipsoid.convertLos(entry, los),
+ tile.getLatitudeIndex(closeGuess.getLatitude()),
+ tile.getLongitudeIndex(closeGuess.getLongitude()));
+ } else {
+ final Vector3D delta = ellipsoid.transform(closeGuess).subtract(position);
+ final double s = Vector3D.dotProduct(delta, los) / los.getNormSq();
+ final GeodeticPoint projected = ellipsoid.transform(new Vector3D(1, position, s, los),
+ ellipsoid.getBodyFrame(), null);
+ final Tile tile = cache.getTile(projected.getLatitude(), projected.getLongitude());
+ return tile.pixelIntersection(projected, ellipsoid.convertLos(projected, los),
+ tile.getLatitudeIndex(projected.getLatitude()),
+ tile.getLongitudeIndex(projected.getLongitude()));
+ }
} catch (OrekitException oe) {
throw new RuggedException(oe, oe.getSpecifier(), oe.getParts());
}
--
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