From de07271160be32034434abda022f24e58aa19ce6 Mon Sep 17 00:00:00 2001
From: Luc Maisonobe <luc@orekit.org>
Date: Thu, 21 Feb 2019 11:01:04 +0100
Subject: [PATCH] Fixed safety check.
---
.../duvenhage/DuvenhageAlgorithm.java | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/src/main/java/org/orekit/rugged/intersection/duvenhage/DuvenhageAlgorithm.java b/src/main/java/org/orekit/rugged/intersection/duvenhage/DuvenhageAlgorithm.java
index ba6e1b8e..78f709bf 100644
--- a/src/main/java/org/orekit/rugged/intersection/duvenhage/DuvenhageAlgorithm.java
+++ b/src/main/java/org/orekit/rugged/intersection/duvenhage/DuvenhageAlgorithm.java
@@ -242,13 +242,6 @@ public class DuvenhageAlgorithm implements IntersectionAlgorithm {
} else {
// extremely rare case: we have lost the intersection
- // safety check, which should never be triggered...
- if (currentGuess.getAltitude() <
- tile.interpolateElevation(currentGuess.getLatitude(), currentGuess.getLongitude())) {
- // this should never happen, we are below the DEM
- throw RuggedException.createInternalError(null);
- }
-
// find a start point for new search, leaving the current cell behind
final double cellBoundaryLatitude = tile.getLatitudeAtIndex(topoLOS.getY() <= 0 ? iLat : iLat + 1);
final double cellBoundaryLongitude = tile.getLongitudeAtIndex(topoLOS.getX() <= 0 ? iLon : iLon + 1);
@@ -256,6 +249,18 @@ public class DuvenhageAlgorithm implements IntersectionAlgorithm {
longitudeCrossing(ellipsoid, projectedP, los, cellBoundaryLongitude, projectedP),
projectedP),
STEP, los);
+ final GeodeticPoint egp = ellipsoid.transform(cellExit, ellipsoid.getBodyFrame(), null);
+ final NormalizedGeodeticPoint cellExitGP = new NormalizedGeodeticPoint(egp.getLatitude(),
+ egp.getLongitude(),
+ egp.getAltitude(),
+ currentGuess.getLongitude());
+ if (tile.interpolateElevation(cellExitGP.getLatitude(), cellExitGP.getLongitude()) >= cellExitGP.getAltitude()) {
+ // extremely rare case! The line-of-sight traversed the Digital Elevation Model
+ // during the very short forward step we used to move to next cell
+ // we consider this point to be OK
+ return cellExitGP;
+ }
+
// We recompute fully a new guess, starting from the point after current cell
final GeodeticPoint currentGuessGP = intersection(ellipsoid, cellExit, los);
--
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