importScripts('zlib.js');
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importScripts('png.js');
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importScripts('ElevDecompress.js');
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importScripts('jpglib2.js');
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self.addEventListener('message', function (e) {
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var data = e.data;
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data.rejected = false;
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//data.zeroLevel = false; //for rejected data (when using MPT) - There are 6 mpt requests at the begining that should not be parsed for elevation. Nevertheless, we MUST NOT mark them as unavailiable tiles.
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if (isPNG(data)) {
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var png = new PNG(new Uint8Array(data.buffer));
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//postMessage(JSON.stringify({ type: 'debug', msg: data.deferedId + " 1" }));
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var pixels = png.decodePixels();
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var out = new Int16Array(pixels.length / 2);
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for (var i = 0; i < pixels.length / 2; i++) {
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out[i] = (pixels[i * 2] << 8 | pixels[i * 2 + 1]);
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// -1 is null value, do not change
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if (out[i] != 65535) // -1 sint16
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out[i] = out[i] * 0.3048;
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}
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data.buffer = out;
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postMessage(data/*, [data.buffer.buffer]*/);
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}
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else if (isMPT(data)) {
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var bBoxSize = 96;
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var dv = new DataView(data.buffer);
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var dataBeginOffset = dv.getUint32(64, true);
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var dataSize = dv.getUint32(68, true);
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var extend = dv.getUint32(72, true);
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var parts = dv.getUint32(76, true);
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var sizeColor = (dv.getUint32(bBoxSize + 4, true) & 0xffffff) - (dv.getUint32(bBoxSize + 0, true) & 0xffffff);
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var sizeElevation = (dv.getUint32(bBoxSize + 8, true) & 0xffffff) - (dv.getUint32(bBoxSize + 4, true) & 0xffffff);
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var dataStreamBegin = bBoxSize + sizeColor + dataBeginOffset;
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var channelOffset = (dv.getUint32(dataStreamBegin + 0, true) & 0x00FFFFFF); //16
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var channelType = dv.getUint32(dataStreamBegin + 4, true);
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var channelData = String.fromCharCode((channelType) >> 24);
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var dataStartPoint = dataStreamBegin + channelOffset;
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var dataEndPoint = dataStartPoint + sizeElevation;
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if (channelData == 'N') { // PNG16.8
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var result = PNG16_8Decompress(data.buffer.slice(dataStartPoint, dataEndPoint));
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data.buffer = result;
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postMessage(data);
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}
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else if (channelData == 'B') { //JPEG
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var result = JPEGDecompress(data.buffer.slice(dataStartPoint, dataEndPoint));
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var out = new Uint16Array(result.byteLength);
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for (var i = 0; i < 256 * 256; i++) {
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var value = Math.fmod(result[i], Math.pow(2, 32));
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if (value != 65535) {
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out[i] = value;
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}
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}
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data.buffer = out;
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postMessage(data);
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}
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else if (channelData == 'A') { //PNG16
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var out = PNGDecompress(data.buffer.slice(dataStartPoint, dataEndPoint));
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data.buffer = out;
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postMessage(data);
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} else { // debugging and other formats currently not supported
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//var len = this.heightMapWidth * this.heightMapHeight;
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//var buf = new Int16Array(len);
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//var val = 0;
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//for (var i = 0; i < len; i++)
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// buf[i] = val;
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//data.buffer = buf;
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//postMessage(data/*, [data.buffer.buffer]*/);
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}
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}
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else {
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// I dont know. reject.
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data.rejected = true;
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postMessage(data);
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}
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});
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function isPNG(data) {
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if (data.buffer.byteLength > 2) {
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var PNGArray = new Uint8Array(data.buffer.byteLength > 0 ? data.buffer.slice(1, 4) : 0);
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var _isPNG = ((PNGArray.length == 0) || (PNGArray[0] == 'P'.charCodeAt() && PNGArray[1] == 'N'.charCodeAt() && PNGArray[2] == 'G'.charCodeAt()));
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return _isPNG;
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}
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return false;
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}
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function isMPT(data) {
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if (data.buffer.byteLength > 80) {
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var bBoxSize = 96;
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var dv = new DataView(data.buffer);
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var dataBeginOffset = dv.getUint32(64, true);
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var dataSize = dv.getUint32(68, true);
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var extend = dv.getUint32(72, true);
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var parts = dv.getUint32(76, true);
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if (parts == 1) // There should be only one part
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return true;
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else
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return false;
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}
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return false;
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}
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//fmod
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Math.fmod = function (a, b) { return Number((a - (Math.floor(a / b) * b)).toPrecision(8)); };
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//random buffer should not be used... only for debugging
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function getRandomIntInclusive(min, max) {
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return Math.floor(Math.random() * (max - min + 1)) + min;
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}
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//decompress JPEG - use jpglib2.js
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function JPEGDecompress(array) {
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var minval = 0;
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var maxval = 0;
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var m_prelist;
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var byteArray = new Uint8Array(array);
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var dvJPEG = new DataView(byteArray.buffer);
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minval = dvJPEG.getFloat32(0,true);
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maxval = dvJPEG.getFloat32(4, true);
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m_prelist = byteArray.slice(8, 8 + 256); // 2* sizeof(float) + PRE_LISTSIZE
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var buffer8 = byteArray.slice(256 + 8, byteArray.byteLength);
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var jpegDecompressed = decode(buffer8, true, 1);
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if (!isNaN(jpegDecompressed.data[0])) {
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var jpegElev = new JPEGElevDecompress();
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var result = jpegElev.ElevDecompress(jpegDecompressed, m_prelist, minval, maxval);
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return result;
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} else {
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console.error("Error while JPEG Decompressing");
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}
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}
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//decompress png - use png.js library
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function PNGDecompress(array) {
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var byteArray = new Uint8Array(array);
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var dvPNG = new DataView(array);
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var min = dvPNG.getFloat32(0, true);
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var max = dvPNG.getFloat32(4, true);
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var delta = max - min;
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var slicedArray = byteArray.slice(8, byteArray.buffer.byteLength);
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var png = new PNG(new Uint8Array(slicedArray));
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var pixels = png.decodePixels();
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var out = new Float32Array(pixels.length / 2);
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var dvwords = new DataView(pixels.buffer);
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for (var i = 0; i < pixels.length / 2; i++) {
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out[i] = dvwords.getUint16(i * 2);
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//out[i] = ( pixels[i*2]<<8 | pixels[i*2+1] );
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if (out[i] != 65535) // -1 sint
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out[i] = out[i] * delta/65535.0 + min;
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}
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return out;
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}
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// decompress PNG16.8
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function PNG16_8Decompress(array) {
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var sizeOne = 0;
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var sizeTwo = 0;
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var byteArray = new Uint8Array(array);
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var dv168 = new DataView(byteArray.buffer);
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sizeOne = dv168.getUint32(0,true);
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sizeTwo = dv168.getUint32(4,true);
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var channelSizeN = 8 + sizeOne + sizeTwo;
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//first buffer (words)
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var firstBuffer = byteArray.slice(8, 8 + sizeOne);
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var firstPNG = new PNG(new Uint8Array(firstBuffer));
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var pixels = firstPNG.decodePixels();
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var pixels1View = new DataView(pixels.buffer);
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//second buffer (bytes)
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var secondBuffer = byteArray.slice(8 + sizeOne,channelSizeN);
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var secondPNG = new PNG(new Uint8Array(secondBuffer));
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var pixels2 = secondPNG.decodePixels();
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var pixels2View = new DataView(pixels.buffer);
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var floatArray = new Float32Array(256*256);
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var feet2meter = 0.3048;
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for (var iii = 0; iii < 256; iii++)
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for (var jjj = 0; jjj < 256 ; jjj++) {
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floatArray[jjj + iii * 256] = (pixels1View.getInt16((jjj + iii * 256)*2) + pixels2[jjj + iii * 256] / 256) * feet2meter;
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}
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return floatArray;
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}
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