From dd7086c5abea8e97c31172fc892317a076ecf0ba Mon Sep 17 00:00:00 2001
From: Luc Maisonobe <luc@orekit.org>
Date: Sat, 15 Mar 2014 18:44:44 +0100
Subject: [PATCH] Work In Progress on duvenhage algorithm.
---
.../core/duvenhage/DuvenhageAlgorithm.java | 48 +++++++++++++------
1 file changed, 34 insertions(+), 14 deletions(-)
diff --git a/rugged-core/src/main/java/org/orekit/rugged/core/duvenhage/DuvenhageAlgorithm.java b/rugged-core/src/main/java/org/orekit/rugged/core/duvenhage/DuvenhageAlgorithm.java
index 8a8076e1..73e70f49 100644
--- a/rugged-core/src/main/java/org/orekit/rugged/core/duvenhage/DuvenhageAlgorithm.java
+++ b/rugged-core/src/main/java/org/orekit/rugged/core/duvenhage/DuvenhageAlgorithm.java
@@ -100,27 +100,47 @@ public class DuvenhageAlgorithm implements IntersectionAlgorithm {
// find where line-of-sight exit tile
final LimitPoint exit = findExit(tile, ellipsoid, position, los);
final Deque<GeodeticPoint> splitPointsQueue = new ArrayDeque<GeodeticPoint>();
- splitPointsQueue.push(exit.getPoint());
+ splitPointsQueue.addFirst(exit.getPoint());
while (!splitPointsQueue.isEmpty()) {
- final GeodeticPoint next = splitPointsQueue.pop();
+ final GeodeticPoint next = splitPointsQueue.removeFirst();
final int nextLatIndex = tile.getLatitudeIndex(next.getLatitude());
final int nextLonIndex = tile.getLontitudeIndex(next.getLongitude());
+ if (currentLatIndex == nextLatIndex && currentLonIndex == nextLonIndex) {
+
+ // we have narrowed the search down to a single Digital Elevation Model pixel
+ if (next.getAltitude() <= tile.getElevationAtIndices(nextLatIndex, nextLonIndex) ||
+ next.getAltitude() <= tile.getElevationAtIndices(nextLatIndex, nextLonIndex + 1) ||
+ next.getAltitude() <= tile.getElevationAtIndices(nextLatIndex + 1, nextLonIndex) ||
+ next.getAltitude() <= tile.getElevationAtIndices(nextLatIndex + 1, nextLonIndex + 1)) {
+ // TODO: compute intersection
+ throw RuggedException.createInternalError(null);
+ } else {
+ // no intersection on this pixel, we can proceed to next part of the line-of-sight
+ current = next;
+ }
- // find the largest level in the min/max kd-tree were entry and exit share a sub-tile
- int level = tile.getMergeLevel(currentLatIndex, currentLonIndex, nextLatIndex, nextLonIndex);
- if (level < 0) {
- // TODO: push intermediate points at sub-tiles boundaries on the queue
- throw RuggedException.createInternalError(null);
- }
-
- if (next.getAltitude() >= tile.getMaxElevation(nextLatIndex, nextLonIndex, level)) {
- // the line segment is fully above Digital Elevation Model
- // we can safely reject it and proceed to next part of the line-of-sight
- current = next;
} else {
- // TODO: split line-of-sight
+
+ // find the largest level in the min/max kd-tree at which entry and exit share a sub-tile
+ int level = tile.getMergeLevel(currentLatIndex, currentLonIndex, nextLatIndex, nextLonIndex);
+ if (level < 0) {
+ // TODO: push intermediate points at sub-tiles boundaries on the queue
+ throw RuggedException.createInternalError(null);
+ } else {
+ if (next.getAltitude() >= tile.getMaxElevation(nextLatIndex, nextLonIndex, level)) {
+ // the line-of-sight segment is fully above Digital Elevation Model
+ // we can safely reject it and proceed to next part of the line-of-sight
+ current = next;
+ } else {
+ // the line-of-sight segment has at least some undecided parts which may
+ // intersect the Digital Elevation Model, we need to refine the
+ // search by using a finer-grained level in the min/max kd-tree
+ // TODO: split line-of-sight
+ }
+ }
+
}
}
--
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