001/*
002 * Copyright (c) 2003 Objectix Pty Ltd  All rights reserved.
003 *
004 * This library is free software; you can redistribute it and/or
005 * modify it under the terms of the GNU Lesser General Public
006 * License as published by the Free Software Foundation.
007 *
008 * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESSED OR IMPLIED
009 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
010 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
011 * DISCLAIMED.  IN NO EVENT SHALL OBJECTIX PTY LTD BE LIABLE FOR ANY
012 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
013 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
014 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
015 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
016 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
017 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
018 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
019 */
020package org.openstreetmap.josm.data.projection.datum;
021
022import java.io.IOException;
023import java.io.InputStream;
024import java.io.Serializable;
025import java.nio.charset.StandardCharsets;
026import java.util.ArrayList;
027import java.util.HashMap;
028import java.util.List;
029import java.util.Map;
030
031import org.openstreetmap.josm.tools.Logging;
032
033/**
034 * Models the NTv2 format Grid Shift File and exposes methods to shift
035 * coordinate values using the Sub Grids contained in the file.
036 * <p>The principal reference for the algorithms used is the
037 * 'GDAit Software Architecture Manual' produced by the <a
038 * href='http://www.sli.unimelb.edu.au/gda94'>Geomatics
039 * Department of the University of Melbourne</a>
040 * <p>This library reads binary NTv2 Grid Shift files in Big Endian
041 * (Canadian standard) or Little Endian (Australian Standard) format.
042 * The older 'Australian' binary format is not supported, only the
043 * official Canadian format, which is now also used for the national
044 * Australian Grid.
045 * <p>Grid Shift files can be read as InputStreams or RandomAccessFiles.
046 * Loading an InputStream places all the required node information
047 * (accuracy data is optional) into heap based Java arrays. This is the
048 * highest performance option, and is useful for large volume transformations.
049 * Non-file data sources (eg using an SQL Blob) are also supported through
050 * InputStream. The RandomAccessFile option has a much smaller memory
051 * footprint as only the Sub Grid headers are stored in memory, but
052 * transformation is slower because the file must be read a number of
053 * times for each transformation.
054 * <p>Coordinates may be shifted Forward (ie from and to the Datums specified
055 * in the Grid Shift File header) or Reverse. The reverse transformation
056 * uses an iterative approach to approximate the Grid Shift, as the
057 * precise transformation is based on 'from' datum coordinates.
058 * <p>Coordinates may be specified
059 * either in Seconds using Positive West Longitude (the original NTv2
060 * arrangement) or in decimal Degrees using Positive East Longitude.
061 *
062 * @author Peter Yuill
063 * Modified for JOSM :
064 * - removed the RandomAccessFile mode (Pieren)
065 * @since 2507
066 */
067public class NTV2GridShiftFile implements Serializable {
068
069    private static final long serialVersionUID = 1L;
070
071    private int overviewHeaderCount;
072    private int subGridHeaderCount;
073    private int subGridCount;
074    private String shiftType;
075    private String version;
076    private String fromEllipsoid = "";
077    private String toEllipsoid = "";
078    private double fromSemiMajorAxis;
079    private double fromSemiMinorAxis;
080    private double toSemiMajorAxis;
081    private double toSemiMinorAxis;
082
083    private NTV2SubGrid[] topLevelSubGrid;
084    private NTV2SubGrid lastSubGrid;
085
086    private static void readBytes(InputStream in, byte[] b) throws IOException {
087        if (in.read(b) < b.length) {
088            Logging.error("Failed to read expected amount of bytes ("+ b.length +") from stream");
089        }
090    }
091
092    /**
093     * Load a Grid Shift File from an InputStream. The Grid Shift node
094     * data is stored in Java arrays, which will occupy about the same memory
095     * as the original file with accuracy data included, and about half that
096     * with accuracy data excluded. The size of the Australian national file
097     * is 4.5MB, and the Canadian national file is 13.5MB
098     * <p>The InputStream is closed by this method.
099     *
100     * @param in Grid Shift File InputStream
101     * @param loadAccuracy is Accuracy data to be loaded as well as shift data?
102     * @throws IOException if any I/O error occurs
103     */
104    public void loadGridShiftFile(InputStream in, boolean loadAccuracy) throws IOException {
105        byte[] b8 = new byte[8];
106        fromEllipsoid = "";
107        toEllipsoid = "";
108        topLevelSubGrid = null;
109        readBytes(in, b8);
110        String overviewHeaderCountId = new String(b8, StandardCharsets.UTF_8);
111        if (!"NUM_OREC".equals(overviewHeaderCountId))
112            throw new IllegalArgumentException("Input file is not an NTv2 grid shift file");
113        boolean bigEndian;
114        readBytes(in, b8);
115        overviewHeaderCount = NTV2Util.getIntBE(b8, 0);
116        if (overviewHeaderCount == 11) {
117            bigEndian = true;
118        } else {
119            overviewHeaderCount = NTV2Util.getIntLE(b8, 0);
120            if (overviewHeaderCount == 11) {
121                bigEndian = false;
122            } else
123                throw new IllegalArgumentException("Input file is not an NTv2 grid shift file");
124        }
125        readBytes(in, b8);
126        readBytes(in, b8);
127        subGridHeaderCount = NTV2Util.getInt(b8, bigEndian);
128        readBytes(in, b8);
129        readBytes(in, b8);
130        subGridCount = NTV2Util.getInt(b8, bigEndian);
131        NTV2SubGrid[] subGrid = new NTV2SubGrid[subGridCount];
132        readBytes(in, b8);
133        readBytes(in, b8);
134        shiftType = new String(b8, StandardCharsets.UTF_8);
135        readBytes(in, b8);
136        readBytes(in, b8);
137        version = new String(b8, StandardCharsets.UTF_8);
138        readBytes(in, b8);
139        readBytes(in, b8);
140        fromEllipsoid = new String(b8, StandardCharsets.UTF_8);
141        readBytes(in, b8);
142        readBytes(in, b8);
143        toEllipsoid = new String(b8, StandardCharsets.UTF_8);
144        readBytes(in, b8);
145        readBytes(in, b8);
146        fromSemiMajorAxis = NTV2Util.getDouble(b8, bigEndian);
147        readBytes(in, b8);
148        readBytes(in, b8);
149        fromSemiMinorAxis = NTV2Util.getDouble(b8, bigEndian);
150        readBytes(in, b8);
151        readBytes(in, b8);
152        toSemiMajorAxis = NTV2Util.getDouble(b8, bigEndian);
153        readBytes(in, b8);
154        readBytes(in, b8);
155        toSemiMinorAxis = NTV2Util.getDouble(b8, bigEndian);
156
157        for (int i = 0; i < subGridCount; i++) {
158            subGrid[i] = new NTV2SubGrid(in, bigEndian, loadAccuracy);
159        }
160        topLevelSubGrid = createSubGridTree(subGrid);
161        lastSubGrid = topLevelSubGrid[0];
162    }
163
164    /**
165     * Create a tree of Sub Grids by adding each Sub Grid to its parent (where
166     * it has one), and returning an array of the top level Sub Grids
167     * @param subGrid an array of all Sub Grids
168     * @return an array of top level Sub Grids with lower level Sub Grids set.
169     */
170    private static NTV2SubGrid[] createSubGridTree(NTV2SubGrid... subGrid) {
171        int topLevelCount = 0;
172        Map<String, List<NTV2SubGrid>> subGridMap = new HashMap<>();
173        for (int i = 0; i < subGrid.length; i++) {
174            if ("NONE".equalsIgnoreCase(subGrid[i].getParentSubGridName())) {
175                topLevelCount++;
176            }
177            subGridMap.put(subGrid[i].getSubGridName(), new ArrayList<NTV2SubGrid>());
178        }
179        NTV2SubGrid[] topLevelSubGrid = new NTV2SubGrid[topLevelCount];
180        topLevelCount = 0;
181        for (int i = 0; i < subGrid.length; i++) {
182            if ("NONE".equalsIgnoreCase(subGrid[i].getParentSubGridName())) {
183                topLevelSubGrid[topLevelCount++] = subGrid[i];
184            } else {
185                List<NTV2SubGrid> parent = subGridMap.get(subGrid[i].getParentSubGridName());
186                parent.add(subGrid[i]);
187            }
188        }
189        NTV2SubGrid[] nullArray = new NTV2SubGrid[0];
190        for (int i = 0; i < subGrid.length; i++) {
191            List<NTV2SubGrid> subSubGrids = subGridMap.get(subGrid[i].getSubGridName());
192            if (!subSubGrids.isEmpty()) {
193                NTV2SubGrid[] subGridArray = subSubGrids.toArray(nullArray);
194                subGrid[i].setSubGridArray(subGridArray);
195            }
196        }
197        return topLevelSubGrid;
198    }
199
200    /**
201     * Shift a coordinate in the Forward direction of the Grid Shift File.
202     *
203     * @param gs A GridShift object containing the coordinate to shift
204     * @return True if the coordinate is within a Sub Grid, false if not
205     */
206    public boolean gridShiftForward(NTV2GridShift gs) {
207        NTV2SubGrid subGrid = null;
208        if (lastSubGrid != null) {
209            // Try the last sub grid first, big chance the coord is still within it
210            subGrid = lastSubGrid.getSubGridForCoord(gs.getLonPositiveWestSeconds(), gs.getLatSeconds());
211        }
212        if (subGrid == null) {
213            subGrid = getSubGrid(topLevelSubGrid, gs.getLonPositiveWestSeconds(), gs.getLatSeconds());
214        }
215        if (subGrid == null) {
216            return false;
217        } else {
218            subGrid.interpolateGridShift(gs);
219            gs.setSubGridName(subGrid.getSubGridName());
220            lastSubGrid = subGrid;
221            return true;
222        }
223    }
224
225    /**
226     * Shift a coordinate in the Reverse direction of the Grid Shift File.
227     *
228     * @param gs A GridShift object containing the coordinate to shift
229     * @return True if the coordinate is within a Sub Grid, false if not
230     */
231    public boolean gridShiftReverse(NTV2GridShift gs) {
232        // set up the first estimate
233        NTV2GridShift forwardGs = new NTV2GridShift();
234        forwardGs.setLonPositiveWestSeconds(gs.getLonPositiveWestSeconds());
235        forwardGs.setLatSeconds(gs.getLatSeconds());
236        for (int i = 0; i < 4; i++) {
237            if (!gridShiftForward(forwardGs))
238                return false;
239            forwardGs.setLonPositiveWestSeconds(
240                    gs.getLonPositiveWestSeconds() - forwardGs.getLonShiftPositiveWestSeconds());
241            forwardGs.setLatSeconds(gs.getLatSeconds() - forwardGs.getLatShiftSeconds());
242        }
243        gs.setLonShiftPositiveWestSeconds(-forwardGs.getLonShiftPositiveWestSeconds());
244        gs.setLatShiftSeconds(-forwardGs.getLatShiftSeconds());
245        gs.setLonAccuracyAvailable(forwardGs.isLonAccuracyAvailable());
246        if (forwardGs.isLonAccuracyAvailable()) {
247            gs.setLonAccuracySeconds(forwardGs.getLonAccuracySeconds());
248        }
249        gs.setLatAccuracyAvailable(forwardGs.isLatAccuracyAvailable());
250        if (forwardGs.isLatAccuracyAvailable()) {
251            gs.setLatAccuracySeconds(forwardGs.getLatAccuracySeconds());
252        }
253        return true;
254    }
255
256    /**
257     * Find the finest SubGrid containing the coordinate, specified in Positive West Seconds
258     * @param topLevelSubGrid top level subgrid
259     * @param lon Longitude in Positive West Seconds
260     * @param lat Latitude in Seconds
261     * @return The SubGrid found or null
262     */
263    private static NTV2SubGrid getSubGrid(NTV2SubGrid[] topLevelSubGrid, double lon, double lat) {
264        NTV2SubGrid sub = null;
265        for (NTV2SubGrid topLevel : topLevelSubGrid) {
266            sub = topLevel.getSubGridForCoord(lon, lat);
267            if (sub != null) {
268                break;
269            }
270        }
271        return sub;
272    }
273
274    @Override
275    public String toString() {
276        char endl = '\n';
277        return "Headers  : " + overviewHeaderCount + endl +
278                "Sub Hdrs : " + subGridHeaderCount + endl +
279                "Sub Grids: " + subGridCount + endl +
280                "Type     : " + shiftType + endl +
281                "Version  : " + version + endl +
282                "Fr Ellpsd: " + fromEllipsoid + endl +
283                "To Ellpsd: " + toEllipsoid + endl +
284                "Fr Maj Ax: " + fromSemiMajorAxis + endl +
285                "Fr Min Ax: " + fromSemiMinorAxis + endl +
286                "To Maj Ax: " + toSemiMajorAxis + endl +
287                "To Min Ax: " + toSemiMinorAxis;
288    }
289
290    /**
291     * Returns "from" ellipsoid identifier.
292     * @return "from" ellipsoid identifier
293     */
294    public String getFromEllipsoid() {
295        return fromEllipsoid;
296    }
297
298    /**
299     * Returns "to" ellipsoid identifier.
300     * @return "to" ellipsoid identifier
301     */
302    public String getToEllipsoid() {
303        return toEllipsoid;
304    }
305}