From fee054d150f409c6283c6b863053a45fce287329 Mon Sep 17 00:00:00 2001
From: Luc Maisonobe <luc@orekit.org>
Date: Mon, 17 Mar 2014 20:26:47 +0100
Subject: [PATCH] Work In Progress on duvenhage algorithm.
---
.../core/duvenhage/DuvenhageAlgorithm.java | 40 ++++++++++++++++---
1 file changed, 34 insertions(+), 6 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 1cc381b4..b786117b 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
@@ -99,12 +99,12 @@ 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.addFirst(exit.getPoint());
+ final Deque<GeodeticPoint> lineOfSightQueue = new ArrayDeque<GeodeticPoint>();
+ lineOfSightQueue.addFirst(exit.getPoint());
- while (!splitPointsQueue.isEmpty()) {
+ while (!lineOfSightQueue.isEmpty()) {
- final GeodeticPoint next = splitPointsQueue.removeFirst();
+ final GeodeticPoint next = lineOfSightQueue.removeFirst();
final int nextLatIndex = tile.getLatitudeIndex(next.getLatitude());
final int nextLonIndex = tile.getLontitudeIndex(next.getLongitude());
if (currentLatIndex == nextLatIndex && currentLonIndex == nextLonIndex) {
@@ -124,7 +124,7 @@ public class DuvenhageAlgorithm implements IntersectionAlgorithm {
} else {
// 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);
+ final 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);
@@ -137,7 +137,35 @@ public class DuvenhageAlgorithm implements IntersectionAlgorithm {
// 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
+
+ // push the point back into the queue
+ lineOfSightQueue.addFirst(next);
+
+ // increase level to have a more fine-grained min/max raster
+ // (we go closer to individual pixels, or un-merge the merged min/max)
+ // this un-merging implies finding the boundary between sub-tiles that
+ // are merged at level l and not merged at level l+1. This boundary is
+ // an iso-latitude if the merge is a row merging and is an iso-longitude
+ // if the merge is a column merging. We therefore first identify the
+ // row/column corresponding to the merging, then find the intersection of
+ // the line-of-sight with the iso-surface, then insert this new intermediate
+ // point in the queue
+ final Vector3D mergePoint;
+ if (tile.isColumnMerging(level + 1)) {
+ final double longitudeMerge =
+ tile.getLongitudeAtIndex(tile.getMergingColumn(currentLonIndex, level + 1));
+ mergePoint = ellipsoid.pointAtLongitude(position, los, longitudeMerge);
+ } else {
+ final double latitudeSplit =
+ tile.getLatitudeAtIndex(tile.getMergingRow(currentLatIndex, level + 1));
+ mergePoint = ellipsoid.pointAtLatitude(position, los, latitudeSplit);
+ }
+
+ // push the intermediate point at sub-tile split into the queue
+ lineOfSightQueue.addFirst(ellipsoid.transform(mergePoint, ellipsoid.getBodyFrame(), null));
+
+ // the current point remains the same
+
}
}
--
GitLab