Tile.java
/* Copyright 2013-2020 CS GROUP
* Licensed to CS GROUP (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.orekit.rugged.raster;
import org.hipparchus.geometry.euclidean.threed.Vector3D;
import org.orekit.bodies.GeodeticPoint;
import org.orekit.rugged.utils.NormalizedGeodeticPoint;
/** Interface representing a raster tile.
* <p>
* The elevations are considered to be at the <em>center</em> of each cells.
* The minimum latitude and longitude hence correspond to the <em>center</em>
* of the most South-West cell, and the maximum latitude and longitude
* correspond to the <em>center</em> of the most North-East cell.
* </p>
* @author Luc Maisonobe
* @author Guylaine Prat
*/
public interface Tile extends UpdatableTile {
/** Enumerate for point location with respect to the interpolation grid of a tile.
* <p>
* Elevations in a tile are interpolated using the four neighboring points
* in a grid: (i, j), (i+1, j), (i, j+1), (i+1), (j+1). This implies that a point
* can be interpolated only if the elevation for these four points is available
* in the tile. A consequence is that a point in the northernmost row (resp.
* easternmost column) miss neighboring points at row j+1 (resp. neighboring points
* at column i+1) and therefore cannot be interpolated.
* </p>
* <p>
* This enumerate represent the position of a point taking this off-by-one property
* into account, the value {@link #HAS_INTERPOLATION_NEIGHBORS} correspond to points that
* do have the necessary four neightbors, whereas the other values correspond to points
* that are either completely outside of the tile or within the tile but in either the
* northernmost row or easternmost column.
* </p>
*/
enum Location {
/** Location for points out of tile interpolation grid, in the South-West corner direction. */
SOUTH_WEST,
/** Location for points out of tile interpolation grid, in the West edge direction. */
WEST,
/** Location for points out of tile interpolation grid, in the North-West corner direction.
* <p>
* The point may still be in the tile, but in the northernmost row thus missing required
* interpolation points.
* </p>
*/
NORTH_WEST,
/** Location for points out of tile interpolation grid, in the North edge direction.
* <p>
* The point may still be in the tile, but in the northernmost row thus missing required
* interpolation points.
* </p>
*/
NORTH,
/** Location for points out of tile interpolation grid, in the North-East corner direction.
* <p>
* The point may still be in the tile, but either in the northernmost row or in the
* easternmost column thus missing required interpolation points.
* </p>
*/
NORTH_EAST,
/** Location for points out of tile interpolation grid, in the East edge direction.
* <p>
* The point may still be in the tile, but in the easternmost column thus missing required
* interpolation points.
* </p>
*/
EAST,
/** Location for points out of tile interpolation grid, in the South-East corner direction.
* <p>
* The point may still be in the tile, but in the easternmost column thus missing required
* interpolation points.
* </p>
*/
SOUTH_EAST,
/** Location for points out of tile interpolation grid, in the South edge direction. */
SOUTH,
/** Location for points that do have interpolation neighbors.
* <p>
* The value corresponds to points that can be interpolated using their four
* neighboring points in the grid at indices (i, j), (i+1, j), (i, j+1), (i+1),
* (j+1). This implies that these points are neither in the northernmost latitude
* row nor in the easternmost longitude column.
* </p>
*/
HAS_INTERPOLATION_NEIGHBORS
}
/** Hook called at the end of tile update completion.
*/
void tileUpdateCompleted();
/** Get minimum latitude of grid interpolation points.
* @return minimum latitude of grid interpolation points (rad)
* (latitude of the center of the cells of South row)
*/
double getMinimumLatitude();
/** Get the latitude at some index.
* @param latitudeIndex latitude index
* @return latitude at the specified index (rad)
* (latitude of the center of the cells of specified row)
*/
double getLatitudeAtIndex(int latitudeIndex);
/** Get maximum latitude.
* <p>
* Beware that as a point at maximum latitude is the northernmost
* one of the grid, it doesn't have a northwards neighbor and
* therefore calling {@link #getLocation(double, double) getLocation}
* on such a latitude will return either {@link Location#NORTH_WEST},
* {@link Location#NORTH} or {@link Location#NORTH_EAST}, but can
* <em>never</em> return {@link Location#HAS_INTERPOLATION_NEIGHBORS}!
* </p>
* @return maximum latitude (rad)
* (latitude of the center of the cells of North row)
*/
double getMaximumLatitude();
/** Get minimum longitude.
* @return minimum longitude (rad)
* (longitude of the center of the cells of West column)
*/
double getMinimumLongitude();
/** Get the longitude at some index.
* @param longitudeIndex longitude index
* @return longitude at the specified index (rad)
* (longitude of the center of the cells of specified column)
*/
double getLongitudeAtIndex(int longitudeIndex);
/** Get maximum longitude.
* <p>
* Beware that as a point at maximum longitude is the easternmost
* one of the grid, it doesn't have an eastwards neighbor and
* therefore calling {@link #getLocation(double, double) getLocation}
* on such a longitude will return either {@link Location#SOUTH_EAST},
* {@link Location#EAST} or {@link Location#NORTH_EAST}, but can
* <em>never</em> return {@link Location#HAS_INTERPOLATION_NEIGHBORS}!
* </p>
* @return maximum longitude (rad)
* (longitude of the center of the cells of East column)
*/
double getMaximumLongitude();
/** Get step in latitude (size of one raster element).
* @return step in latitude (rad)
*/
double getLatitudeStep();
/** Get step in longitude (size of one raster element).
* @return step in longitude (rad)
*/
double getLongitudeStep();
/** Get number of latitude rows.
* @return number of latitude rows
*/
int getLatitudeRows();
/** Get number of longitude columns.
* @return number of longitude columns
*/
int getLongitudeColumns();
/** Get the floor latitude index of a point.
* <p>
* The specified latitude is always between index and index+1.
* </p>
* @param latitude geodetic latitude
* @return floor latitude index (it may lie outside of the tile!)
*/
int getFloorLatitudeIndex(double latitude);
/** Get the floor longitude index of a point.
* <p>
* The specified longitude is always between index and index+1.
* </p>
* @param longitude geodetic longitude
* @return floor longitude index (it may lie outside of the tile!)
*/
int getFloorLongitudeIndex(double longitude);
/** Get the minimum elevation in the tile.
* @return minimum elevation in the tile (m)
*/
double getMinElevation();
/** Get the latitude index of min elevation.
* @return latitude index of min elevation*/
int getMinElevationLatitudeIndex();
/** Get the longitude index of min elevation.
* @return longitude index of min elevation*/
int getMinElevationLongitudeIndex();
/** Get the maximum elevation in the tile.
* @return maximum elevation in the tile (m)
*/
double getMaxElevation();
/** Get the latitude index of max elevation.
* @return latitude index of max elevation*/
int getMaxElevationLatitudeIndex();
/** Get the longitude index of max elevation.
* @return longitude index of max elevation*/
int getMaxElevationLongitudeIndex();
/** Get the elevation of an exact grid point.
* @param latitudeIndex grid point index along latitude
* @param longitudeIndex grid point index along longitude
* @return elevation at grid point (m)
*/
double getElevationAtIndices(int latitudeIndex, int longitudeIndex);
/** Interpolate elevation.
* <p>
* In order to cope with numerical accuracy issues when computing
* points at tile boundary, a slight tolerance (typically 1/8 cell)
* around the tile is allowed. Elevation can therefore be interpolated
* (really extrapolated in this case) even for points slightly overshooting
* tile boundaries, using the closest tile cell. Attempting to interpolate
* too far from the tile will trigger an exception.
* </p>
* @param latitude ground point latitude
* @param longitude ground point longitude
* @return interpolated elevation (m)
*/
double interpolateElevation(double latitude, double longitude);
/** Find the intersection of a line-of-sight and a Digital Elevation Model cell.
* @param p point on the line
* @param los line-of-sight, in the topocentric frame (East, North, Zenith) of the point,
* scaled to match radians in the horizontal plane and meters along the vertical axis
* @param latitudeIndex latitude index of the Digital Elevation Model cell
* @param longitudeIndex longitude index of the Digital Elevation Model cell
* @return point corresponding to line-of-sight crossing the Digital Elevation Model surface
* if it lies within the cell, null otherwise
*/
NormalizedGeodeticPoint cellIntersection(GeodeticPoint p, Vector3D los,
int latitudeIndex, int longitudeIndex);
/** Check if a tile covers a ground point.
* @param latitude ground point latitude
* @param longitude ground point longitude
* @return location of the ground point with respect to tile
*/
Location getLocation(double latitude, double longitude);
}