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之前在写影像融合算法的时候，免不了要实现将多光谱影像重采样到全色大小。当时为了不影响融合算法整体开发进度，其中重采样功能用的是GDAL开源库中的Warp接口实现的。
后来发现GDAL Warp接口实现的多光谱到全色影像的重采样主要存在两个问题：1 与原有平台的已有功能不兼容，产生冲突；2 效率较低。因此，决定重新设计和开发一个这样的功能，方便后期软件系统的维护等。
图像处理从形式上来说主要包括两个方面：1 单像素或者邻域像素的处理，比如影像的相加或者滤波运算等；2 图像几何空间变换，如图像的重采样，配准等。
影像重采样的几何空间变换公式如下：
其中 为变换系数，常用的重采样算法主要包括以下三种：1 最近邻；2 双线性；3 三次卷积。
最近邻采样的原理概况起来就是用采样点位置最近的一个像素值替代采样点位置的像素值。在这里插入一点：
通常图像空间变换有两种方法，直接法或者间接法。以图像重采样为例说明如下：直接法：从原始的图像行列初始值开始，根据变换公式，计算采样后的像素位置，并对位置赋值，但是这种方法会出现，原始图像的多个像素点对应到同一采样后的像素点，从而还要增加额外方法进行处理；间接法：是从重采样后图像的行列初始值开始，计算得到其在原始影像中的位置，并根据一定的算法进行计算，得到采样后的值。这种方法简单直接，本文就是采用这样的方法。
最近邻采样的实现算法如下：
首先遍历采样点，根据公式计算采样点在原始图像中的位置，假设位置为 。然后计算与 最近的点，并将其像素值赋为采样点的像素值。其公式如下：
双线性采样和最近邻赋值不同，是找到 最近的四个像素点，然后将距离作为权重分别插值 和 方向，从而插值到采样点位置。具体公式见代码部分。
三次卷积是利用 最近的16个像素点进行插值计算得到。同样也是分别插值 和 方向。具体公式见代码部分。
主要实现了两个版本的差值结果：1 CPU版本；2 GPU版本（初学）。考虑到多光谱和全色影像范围大小不一致的事实，算法首先计算全色和多光谱的重叠区域。话不多说，先看看详细的代码实现过程。
CPU版本：
1 #ifndef RESAMPLECPU_H 2 #define RESAMPLECPU_H 3 4 #include <gdal_alg_priv.h> 5 #include <gdal_priv.h> 6 #include <assert.h> 7 8 9 template<typename T> 10 void ReSampleCPUKernel(const float *mssData, 11 T *resampleData, 12 int mssWidth, 13 int mssHeight, 14 int mssBandCount, 15 int mssOffsetX, 16 int mssOffsetY, 17 int panWidth, 18 int panHeight, 19 float radioX, 20 float radioY, 21 double dfDstNoDataValue, 22 int MethodType) 23 { 24 assert(mssData != NULL); 25 float eps = 0.00001f; 26 for(int idx = 0;idx < panHeight;idx++){ 27 for(int idy = 0;idy<panWidth;idy++){ 28 // 找到对应的MSS像素位置 29 float curX = (float)idx * radioX; 30 float curY = (float)idy * radioY; 31 if(mssData[int(curX)*mssWidth*mssBandCount + int(curY)] == dfDstNoDataValue) 32 { 33 int i = 0; 34 while(i < mssBandCount){ 35 resampleData[idx*panWidth*mssBandCount+i*panWidth + idy] = T(dfDstNoDataValue); 36 i++; 37 } 38 continue; 39 } 40 if(MethodType == 0){ // 最近邻 41 int nearX = (int)(curX + 0.5)>(int)curX?(int)(curX + 1):(int)curX; 42 int nearY = (int)(curY + 0.5)>(int)curY?(int)(curY + 1):(int)curY; 43 if(nearX >= mssHeight - 1){ 44 nearX = mssHeight - 1; 45 } 46 if(nearY >= mssWidth - 1){ 47 nearY = mssWidth - 1; 48 } 49 if(nearX < mssHeight && nearY < mssWidth){ 50 int i = 0; 51 while(i < mssBandCount){ 52 float tmp = mssData[nearX*mssWidth*mssBandCount + i*mssWidth + nearY]; 53 resampleData[idx*panWidth*mssBandCount+i*panWidth + idy] = T(tmp); 54 i++; 55 } 56 } 57 } 58 59 if(MethodType == 1){ // 双线性 60 float dataX = curX - (int)curX; 61 float dataY = curY - (int)curY; 62 int preX = (int)curX; 63 int preY = (int)curY; 64 int postX = (int)curX + 1; 65 int postY = (int)curY + 1; 66 if(postX >= mssHeight - 1){ 67 postX = mssHeight - 1; 68 } 69 if(postY >= mssWidth - 1){ 70 postY = mssWidth - 1; 71 } 72 73 float Wx1 = 1 - dataX; 74 float Wx2 = dataX; 75 float Wy1 = 1 - dataY; 76 float Wy2 = dataY; 77 // 双线性差值核心代码 78 int i = 0; 79 while(i < mssBandCount){ 80 float pMssValue[4] = {0,0,0,0}; 81 pMssValue[0] = mssData[preX*mssWidth*mssBandCount + i*mssWidth + preY]; 82 pMssValue[1] = mssData[preX*mssWidth*mssBandCount + i*mssWidth + postY]; 83 pMssValue[2] = mssData[postX*mssWidth*mssBandCount + i*mssWidth + preY]; 84 pMssValue[3] = mssData[postX*mssWidth*mssBandCount + i*mssWidth + postY]; 85 float tmp = Wy1*(Wx1*pMssValue[0] + Wx2*pMssValue[2]) + Wy2*(Wx1*pMssValue[1] + Wx2*pMssValue[3]); 86 resampleData[idx*panWidth*mssBandCount+i*panWidth + idy] = T(tmp); 87 i++; 88 } 89 } 90 91 92 if(MethodType == 2){ // 双三次卷积 93 float dataX = curX - (int)curX; 94 float dataY = curY - (int)curY; 95 int preX1 = (int)curX - 1; 96 int preX2 = (int)curX; 97 int postX1 = (int)curX + 1; 98 int postX2 = (int)curX + 2; 99 int preY1 = (int)curY - 1; 100 int preY2 = (int)curY; 101 int postY1 = (int)curY + 1; 102 int postY2 = (int)curY + 2; 103 if(preX1 < 0) preX1 = 0; 104 if(preY1 < 0) preY1 = 0; 105 if(postX1 > mssHeight - 1) postX1 = mssHeight - 1; 106 if(postX2 > mssHeight - 1) postX2 = mssHeight - 1; 107 if(postY1 > mssWidth - 1) postY1 = mssWidth - 1; 108 if(postY2 > mssWidth - 1) postY2 = mssWidth - 1; 109 110 float Wx1 = -1.0f*dataX + 2*dataX*dataX - dataX*dataX*dataX; 111 float Wx2 = 1 - 2*dataX*dataX + dataX*dataX*dataX; 112 float Wx3 = dataX + dataX*dataX - dataX*dataX*dataX; 113 float Wx4 = -1.0f*dataX*dataX + dataX*dataX*dataX; 114 float Wy1 = -1.0f*dataY + 2*dataY*dataY - dataY*dataY*dataY; 115 float Wy2 = 1 - 2*dataY*dataY + dataY*dataY*dataY; 116 float Wy3 = dataY + dataY*dataY - dataY*dataY*dataY; 117 float Wy4 = -1.0f*dataY*dataY + dataY*dataY*dataY; 118 119 int i = 0; 120 while(i < mssBandCount){ 121 float *pMssValue = new float[16]; 122 memset(pMssValue,0,sizeof(float)*16); 123 pMssValue[0] = mssData[preX1*mssWidth*mssBandCount + i*mssWidth + preY1]; 124 pMssValue[1] = mssData[preX1*mssWidth*mssBandCount + i*mssWidth + preY2]; 125 pMssValue[2] = mssData[preX1*mssWidth*mssBandCount + i*mssWidth + postY1]; 126 pMssValue[3] = mssData[preX1*mssWidth*mssBandCount + i*mssWidth + postY2]; 127 128 pMssValue[4] = mssData[preX2*mssWidth*mssBandCount + i*mssWidth + preY1]; 129 pMssValue[5] = mssData[preX2*mssWidth*mssBandCount + i*mssWidth + preY2]; 130 pMssValue[6] = mssData[preX2*mssWidth*mssBandCount + i*mssWidth + postY1]; 131 pMssValue[7] = mssData[preX2*mssWidth*mssBandCount + i*mssWidth + postY2]; 132 133 pMssValue[8] = mssData[postX1*mssWidth*mssBandCount + i*mssWidth + preY1]; 134 pMssValue[9] = mssData[postX1*mssWidth*mssBandCount + i*mssWidth + preY2]; 135 pMssValue[10] = mssData[postX1*mssWidth*mssBandCount + i*mssWidth + postY1]; 136 pMssValue[11] = mssData[postX1*mssWidth*mssBandCount + i*mssWidth + postY2]; 137 138 pMssValue[12] = mssData[postX2*mssWidth*mssBandCount + i*mssWidth + preY1]; 139 pMssValue[13] = mssData[postX2*mssWidth*mssBandCount + i*mssWidth + preY2]; 140 pMssValue[14] = mssData[postX2*mssWidth*mssBandCount + i*mssWidth + postY1]; 141 pMssValue[15] = mssData[postX2*mssWidth*mssBandCount + i*mssWidth + postY2]; 142 143 float tmp = Wy1*(Wx1*pMssValue[0] + Wx2*pMssValue[4] + Wx3*pMssValue[8] + Wx4*pMssValue[12])+ 144 Wy2*(Wx1*pMssValue[1] + Wx2*pMssValue[5] + Wx3*pMssValue[9] + Wx4*pMssValue[13])+ 145 Wy3*(Wx1*pMssValue[2] + Wx2*pMssValue[6] + Wx3*pMssValue[10] + Wx4*pMssValue[14])+ 146 Wy4*(Wx1*pMssValue[3] + Wx2*pMssValue[7] + Wx3*pMssValue[11] + Wx4*pMssValue[15]); 147 resampleData[idx*panWidth*mssBandCount+i*panWidth + idy] = T(tmp); 148 delete []pMssValue;pMssValue = NULL; 149 i++; 150 } 151 } 152 } 153 } 154 } 155 156 int ReSampleCPUApp(const char *mssfileName, 157 const char *panfileName, 158 const char *resamplefileName, 159 int MethodType = 1) 160 { 161 GDALAllRegister(); 162 GDALDataset *poPANDS = (GDALDataset*)GDALOpen(panfileName,GA_ReadOnly); 163 GDALDataset *poMSSDS = (GDALDataset*)GDALOpen(mssfileName,GA_ReadOnly); 164 if(!poPANDS || !poMSSDS) 165 return -1; 166 167 //MSS info 168 int mssBandCount = poMSSDS->GetRasterCount(); 169 int mssWidth = poMSSDS->GetRasterXSize(); 170 int mssHeight = poMSSDS->GetRasterYSize(); 171 double adfMssGeoTransform[6] = {0}; 172 poMSSDS->GetGeoTransform(adfMssGeoTransform); 173 GDALDataType mssDT = poMSSDS->GetRasterBand(1)->GetRasterDataType(); 174 175 int bSrcHasNoData; 176 double dfSrcNoDataValue = 0; 177 dfSrcNoDataValue = GDALGetRasterNoDataValue(poMSSDS->GetRasterBand(1),&bSrcHasNoData); 178 if(!bSrcHasNoData) dfSrcNoDataValue = 0.0; 179 //DT = mssDT; 180 181 int *pBandMap= new int[mssBandCount]; 182 for(int i = 0;i<mssBandCount;i++){ 183 pBandMap[i] = i+1; 184 } 185 186 // PAN Info 187 int panBandCount = poPANDS->GetRasterCount(); 188 int panWidth = poPANDS->GetRasterXSize(); 189 int panHeidht = poPANDS->GetRasterYSize(); 190 double adfPanGeoTransform[6] = {0}; 191 poPANDS->GetGeoTransform(adfPanGeoTransform); 192 GDALDataType panDT = poPANDS->GetRasterBand(1)->GetRasterDataType(); 193 194 // 创建新数据集=======投影信息 195 double adfResampleGeoTransform[6] = {0}; 196 adfResampleGeoTransform[1] = adfPanGeoTransform[1]; 197 adfResampleGeoTransform[5] = adfPanGeoTransform[5]; 198 adfResampleGeoTransform[2] = adfPanGeoTransform[2]; 199 adfResampleGeoTransform[4] = adfPanGeoTransform[4]; 200 if(adfMssGeoTransform[0] >= adfPanGeoTransform[0]){ 201 adfResampleGeoTransform[0] = adfMssGeoTransform[0]; 202 }else{ 203 adfResampleGeoTransform[0] = adfPanGeoTransform[0]; 204 } 205 if(adfMssGeoTransform[3] > adfPanGeoTransform[3]){ 206 adfResampleGeoTransform[3] = adfPanGeoTransform[3]; 207 }else{ 208 adfResampleGeoTransform[3] = adfMssGeoTransform[3]; 209 } 210 211 // 创建新数据集=======影像大小 212 double panEndX = adfPanGeoTransform[0] + panWidth*adfPanGeoTransform[1] + 213 panHeidht*adfPanGeoTransform[2]; 214 double panEndY = adfPanGeoTransform[3] + panHeidht*adfPanGeoTransform[4] + 215 panHeidht*adfPanGeoTransform[5]; 216 217 double mssEndX = adfMssGeoTransform[0] +mssWidth*adfMssGeoTransform[1] + 218 mssHeight*adfMssGeoTransform[2]; 219 double mssEndY = adfMssGeoTransform[3] + mssWidth*adfMssGeoTransform[4] + 220 mssHeight*adfMssGeoTransform[5]; 221 double resampleEndXY[2] = {0}; 222 if(panEndX > mssEndX) 223 resampleEndXY[0] = mssEndX; 224 else 225 resampleEndXY[0] = panEndX; 226 if(panEndY >= mssEndY) 227 resampleEndXY[1] = panEndY; 228 else 229 resampleEndXY[1] = mssEndY; 230 231 // 创建新数据集=======MSS AND PAN 有效长宽 232 int resampleWidth = static_cast<int>((resampleEndXY[0] - adfResampleGeoTransform[0])/adfResampleGeoTransform[1] + 0.5); 233 int resampleHeight = static_cast<int>((resampleEndXY[1] - adfResampleGeoTransform[3])/adfResampleGeoTransform[5] + 0.5); 234 int mssEffectiveWidth = static_cast<int>((resampleEndXY[0] - adfResampleGeoTransform[0])/adfMssGeoTransform[1] + 0.5); 235 int mssEffectiveHeight = static_cast<int>((resampleEndXY[1] - adfResampleGeoTransform[3])/adfMssGeoTransform[5] + 0.5); 236 int panEffectiveWidth = resampleWidth; 237 int panEffectiveHeight = resampleHeight; 238 239 // 创建新数据集=======位置增益大小 240 int mssGainX = static_cast<int>((adfResampleGeoTransform[0] - adfMssGeoTransform[0])/adfMssGeoTransform[1] + 0.5); 241 int mssGainY = static_cast<int>((adfResampleGeoTransform[3] - adfMssGeoTransform[3])/adfMssGeoTransform[5] + 0.5); 242 int panGainX = static_cast<int>((adfResampleGeoTransform[0] - adfPanGeoTransform[0])/adfPanGeoTransform[1] + 0.5); 243 int panGainY = static_cast<int>((adfResampleGeoTransform[3] - adfPanGeoTransform[3])/adfPanGeoTransform[5] + 0.5); 244 245 246 // 创建新数据集=======创建文件 247 GDALDriver *poOutDriver = (GDALDriver*)GDALGetDriverByName("GTIFF"); 248 if(!poOutDriver){ 249 return -1; 250 } 251 GDALDataset *poOutDS = poOutDriver->Create(resamplefileName,resampleWidth, 252 resampleHeight,mssBandCount,mssDT,NULL); 253 poOutDS->SetGeoTransform(adfResampleGeoTransform); 254 poOutDS->SetProjection(poPANDS->GetProjectionRef()); 255 256 257 // 重采样核心代码============图像分块 258 int iNumRow = 256; 259 if(iNumRow > resampleHeight){ 260 iNumRow = 1; 261 } 262 int loopNum = (resampleHeight + iNumRow - 1)/iNumRow; //分块数 263 int nLineSpace,nPixSpace,nBandSpace; 264 nLineSpace = sizeof(float)*mssEffectiveWidth*mssBandCount; 265 nPixSpace = 0; 266 nBandSpace = sizeof(float)*mssEffectiveWidth; 267 268 // 重采样采样比例 269 float radioX = float(adfPanGeoTransform[1]/adfMssGeoTransform[1]); 270 float radioY = float(adfPanGeoTransform[5]/adfMssGeoTransform[5]); 271 272 int mssCurPosX = mssGainX; 273 int mssCurPosY = mssGainY; 274 int mssCurWidth = 0; 275 int mssCurHeight = 0; 276 277 // 重采样核心代码============ 278 for(int i = 0;i<loopNum;i++){ 279 int tmpRowNum = iNumRow; 280 int startR = i*iNumRow; 281 int endR = startR + iNumRow - 1; 282 if(endR>resampleHeight -1){ 283 tmpRowNum = resampleHeight - startR; 284 //endR = startR + tmpRowNum - 1; 285 } 286 //计算读取的MSS影像区域大小 287 int mssCurWidth = mssEffectiveWidth; 288 int mssCurHeight = 0; 289 if(MethodType == 0) 290 mssCurHeight = int(tmpRowNum*radioY); 291 else if(MethodType == 1) 292 mssCurHeight = int(tmpRowNum*radioY)+1; 293 else if(MethodType == 2) 294 mssCurHeight = int(tmpRowNum*radioY)+2; 295 296 if(mssCurHeight + mssCurPosY > mssHeight - 1){ 297 mssCurHeight = mssHeight - mssCurPosY; 298 } 299 300 //创建数据 301 /*float *resampleBuf = (float *)malloc(sizeof(cl_float)*tmpRowNum*resampleWidth*trueBandCount);*/ 302 float *mssBuf = (float *)malloc(sizeof(cl_float)*mssCurHeight*mssCurWidth*mssBandCount); 303 //memset(resampleBuf,0,sizeof(float)*tmpRowNum*resampleWidth*trueBandCount); 304 memset(mssBuf,0,sizeof(float)*mssCurHeight*mssCurWidth*mssBandCount); 305 306 // 读取数据 307 poMSSDS->RasterIO(GF_Read,mssCurPosX,mssCurPosY,mssCurWidth,mssCurHeight, 308 mssBuf,mssCurWidth,mssCurHeight,GDT_Float32,mssBandCount,NULL,nPixSpace, 309 nLineSpace,nBandSpace); 310 311 if(MethodType == 0) 312 mssCurPosY += mssCurHeight; 313 else if(MethodType == 1) 314 mssCurPosY += mssCurHeight - 1; 315 else if(MethodType == 2) 316 mssCurPosY += mssCurHeight - 2; 317 318 // 数据格式转换 319 long sz = tmpRowNum*resampleWidth*mssBandCount; 320 void *resampleBuf = NULL; 321 switch(mssDT){ 322 case GDT_Byte: 323 resampleBuf = new unsigned char[sz]; 324 ReSampleCPUKernel<unsigned char>(mssBuf,(unsigned char*)resampleBuf,mssCurWidth,mssCurHeight,mssBandCount,mssGainX,mssGainY, 325 resampleWidth,tmpRowNum,radioX,radioY,dfSrcNoDataValue,MethodType); 326 poOutDS->RasterIO(GF_Write,0,startR,resampleWidth,tmpRowNum,resampleBuf, 327 resampleWidth,tmpRowNum,mssDT,mssBandCount,NULL,nPixSpace,resampleWidth*mssBandCount*sizeof(unsigned char), 328 resampleWidth*sizeof(unsigned char)); 329 break; 330 case GDT_UInt16: 331 resampleBuf = new unsigned short int[sz]; 332 ReSampleCPUKernel<unsigned short int>(mssBuf,(unsigned short int*)resampleBuf,mssCurWidth,mssCurHeight,mssBandCount,mssGainX,mssGainY, 333 resampleWidth,tmpRowNum,radioX,radioY,dfSrcNoDataValue,MethodType); 334 poOutDS->RasterIO(GF_Write,0,startR,resampleWidth,tmpRowNum,resampleBuf, 335 resampleWidth,tmpRowNum,mssDT,mssBandCount,NULL,nPixSpace,resampleWidth*mssBandCount*sizeof(unsigned short int), 336 resampleWidth*sizeof(unsigned short int)); 337 break; 338 case GDT_Int16: 339 resampleBuf = new short int[sz]; 340 ReSampleCPUKernel<short int>(mssBuf,(short int*)resampleBuf,mssCurWidth,mssCurHeight,mssBandCount,mssGainX,mssGainY, 341 resampleWidth,tmpRowNum,radioX,radioY,dfSrcNoDataValue,MethodType); 342 poOutDS->RasterIO(GF_Write,0,startR,resampleWidth,tmpRowNum,resampleBuf, 343 resampleWidth,tmpRowNum,mssDT,mssBandCount,NULL,nPixSpace,resampleWidth*mssBandCount*sizeof(short int), 344 resampleWidth*sizeof(short int)); 345 break; 346 case GDT_UInt32: 347 resampleBuf = new unsigned int[sz]; 348 ReSampleCPUKernel<unsigned int>(mssBuf,(unsigned int*)resampleBuf,mssCurWidth,mssCurHeight,mssBandCount,mssGainX,mssGainY, 349 resampleWidth,tmpRowNum,radioX,radioY,dfSrcNoDataValue,MethodType); 350 poOutDS->RasterIO(GF_Write,0,startR,resampleWidth,tmpRowNum,resampleBuf, 351 resampleWidth,tmpRowNum,mssDT,mssBandCount,NULL,nPixSpace,resampleWidth*mssBandCount*sizeof(unsigned int), 352 resampleWidth*sizeof(unsigned int)); 353 break; 354 case GDT_Int32: 355 resampleBuf = new int[sz]; 356 ReSampleCPUKernel<int>(mssBuf,(int*)resampleBuf,mssCurWidth,mssCurHeight,mssBandCount,mssGainX,mssGainY, 357 resampleWidth,tmpRowNum,radioX,radioY,dfSrcNoDataValue,MethodType); 358 poOutDS->RasterIO(GF_Write,0,startR,resampleWidth,tmpRowNum,resampleBuf, 359 resampleWidth,tmpRowNum,mssDT,mssBandCount,NULL,nPixSpace,resampleWidth*mssBandCount*sizeof(int), 360 resampleWidth*sizeof(int)); 361 break; 362 case GDT_Float32: 363 resampleBuf = new float[sz]; 364 ReSampleCPUKernel<float>(mssBuf,(float*)resampleBuf,mssCurWidth,mssCurHeight,mssBandCount,mssGainX,mssGainY, 365 resampleWidth,tmpRowNum,radioX,radioY,dfSrcNoDataValue,MethodType); 366 poOutDS->RasterIO(GF_Write,0,startR,resampleWidth,tmpRowNum,resampleBuf, 367 resampleWidth,tmpRowNum,mssDT,mssBandCount,NULL,nPixSpace,resampleWidth*mssBandCount*sizeof(float), 368 resampleWidth*sizeof(float)); 369 break; 370 case GDT_Float64: 371 resampleBuf = new double[sz]; 372 ReSampleCPUKernel<double>(mssBuf,(double*)resampleBuf,mssCurWidth,mssCurHeight,mssBandCount,mssGainX,mssGainY, 373 resampleWidth,tmpRowNum,radioX,radioY,dfSrcNoDataValue,MethodType); 374 poOutDS->RasterIO(GF_Write,0,startR,resampleWidth,tmpRowNum,resampleBuf, 375 resampleWidth,tmpRowNum,mssDT,mssBandCount,NULL,nPixSpace,resampleWidth*mssBandCount*sizeof(double), 376 resampleWidth*sizeof(double)); 377 break; 378 } 379 delete []mssBuf; 380 delete []resampleBuf; 381 std::cout<<i<<std::endl; 382 } 383 delete []pBandMap;pBandMap = NULL; 384 GDALClose((GDALDatasetH)poPANDS); 385 GDALClose((GDALDatasetH)poMSSDS); 386 GDALClose((GDALDatasetH)poOutDS); 387 return 0; 388 } 389 390 #endif
GPU版本：
1 #ifndef RESAMPLEOPENCL_H 2 #define RESAMPLEOPENCL_H 3 4 #include <CL/cl.h> 5 #include <gdal_alg_priv.h> 6 #include <gdal_priv.h> 7 8 #pragma comment(lib,"OpenCL.lib") 9 10 /* 11 @ 功能描述 12 读取源程序，将文本源程序读到内核中 13 */ 14 char* LoadProgSource(const char* cFilename, const char* cPreamble, size_t* szFinalLength) 15 { 16 FILE* pFileStream = NULL; 17 size_t szSourceLength; 18 19 // open the OpenCL source code file 20 pFileStream = fopen(cFilename, "rb"); 21 if(pFileStream == 0) 22 { 23 return NULL; 24 } 25 26 size_t szPreambleLength = strlen(cPreamble); 27 28 // get the length of the source code 29 fseek(pFileStream, 0, SEEK_END); 30 szSourceLength = ftell(pFileStream); 31 fseek(pFileStream, 0, SEEK_SET); 32 33 // allocate a buffer for the source code string and read it in 34 char* cSourceString = (char *)malloc(szSourceLength + szPreambleLength + 1); 35 memcpy(cSourceString, cPreamble, szPreambleLength); 36 if (fread((cSourceString) + szPreambleLength, szSourceLength, 1, pFileStream) != 1) 37 { 38 fclose(pFileStream); 39 free(cSourceString); 40 return 0; 41 } 42 43 // close the file and return the total length of the combined (preamble + source) string 44 fclose(pFileStream); 45 if(szFinalLength != 0) 46 { 47 *szFinalLength = szSourceLength + szPreambleLength; 48 } 49 cSourceString[szSourceLength + szPreambleLength] = ‘\0‘; 50 51 return cSourceString; 52 } 53 54 template<typename T> 55 bool DataTypeTrans(const float *pSrcBuf,T *pDesBuf,long size) 56 { 57 if(pSrcBuf == NULL){ 58 return false; 59 } 60 while(size--){ 61 pDesBuf[size] = T(pSrcBuf[size]); 62 } 63 return true; 64 } 65 66 int ReSampleOpenCLApp(const char *mssfileName, 67 const char *panfileName, 68 const char *resamplefileName, 69 int MethodType = 1) 70 { 71 GDALAllRegister(); 72 GDALDataset *poPANDS = (GDALDataset*)GDALOpen(panfileName,GA_ReadOnly); 73 GDALDataset *poMSSDS = (GDALDataset*)GDALOpen(mssfileName,GA_ReadOnly); 74 if(!poPANDS || !poMSSDS) 75 return -1; 76 77 //MSS info 78 int mssBandCount = poMSSDS->GetRasterCount(); 79 int mssWidth = poMSSDS->GetRasterXSize(); 80 int mssHeight = poMSSDS->GetRasterYSize(); 81 double adfMssGeoTransform[6] = {0}; 82 poMSSDS->GetGeoTransform(adfMssGeoTransform); 83 GDALDataType mssDT = poMSSDS->GetRasterBand(1)->GetRasterDataType(); 84 85 int bSrcHasNoData; 86 float dfSrcNoDataValue = 0; 87 dfSrcNoDataValue = (float)GDALGetRasterNoDataValue(poMSSDS->GetRasterBand(1),&bSrcHasNoData); 88 if(!bSrcHasNoData) dfSrcNoDataValue = 0.0; 89 90 91 // PAN Info 92 int panBandCount = poPANDS->GetRasterCount(); 93 int panWidth = poPANDS->GetRasterXSize(); 94 int panHeidht = poPANDS->GetRasterYSize(); 95 double adfPanGeoTransform[6] = {0}; 96 poPANDS->GetGeoTransform(adfPanGeoTransform); 97 GDALDataType panDT = poPANDS->GetRasterBand(1)->GetRasterDataType(); 98 99 // 创建新数据集=======投影信息 100 double adfResampleGeoTransform[6] = {0}; 101 adfResampleGeoTransform[1] = adfPanGeoTransform[1]; 102 adfResampleGeoTransform[5] = adfPanGeoTransform[5]; 103 adfResampleGeoTransform[2] = adfPanGeoTransform[2]; 104 adfResampleGeoTransform[4] = adfPanGeoTransform[4]; 105 if(adfMssGeoTransform[0] >= adfPanGeoTransform[0]){ 106 adfResampleGeoTransform[0] = adfMssGeoTransform[0]; 107 }else{ 108 adfResampleGeoTransform[0] = adfPanGeoTransform[0]; 109 } 110 if(adfMssGeoTransform[3] > adfPanGeoTransform[3]){ 111 adfResampleGeoTransform[3] = adfPanGeoTransform[3]; 112 }else{ 113 adfResampleGeoTransform[3] = adfMssGeoTransform[3]; 114 } 115 116 // 创建新数据集=======影像大小 117 double panEndX = adfPanGeoTransform[0] + panWidth*adfPanGeoTransform[1] + 118 panHeidht*adfPanGeoTransform[2]; 119 double panEndY = adfPanGeoTransform[3] + panHeidht*adfPanGeoTransform[4] + 120 panHeidht*adfPanGeoTransform[5]; 121 122 double mssEndX = adfMssGeoTransform[0] +mssWidth*adfMssGeoTransform[1] + 123 mssHeight*adfMssGeoTransform[2]; 124 double mssEndY = adfMssGeoTransform[3] + mssWidth*adfMssGeoTransform[4] + 125 mssHeight*adfMssGeoTransform[5]; 126 double resampleEndXY[2] = {0}; 127 if(panEndX > mssEndX) 128 resampleEndXY[0] = mssEndX; 129 else 130 resampleEndXY[0] = panEndX; 131 if(panEndY >= mssEndY) 132 resampleEndXY[1] = panEndY; 133 else 134 resampleEndXY[1] = mssEndY; 135 136 // 创建新数据集=======MSS AND PAN 有效长宽 137 int resampleWidth = static_cast<int>((resampleEndXY[0] - adfResampleGeoTransform[0])/adfResampleGeoTransform[1] + 0.5); 138 int resampleHeight = static_cast<int>((resampleEndXY[1] - adfResampleGeoTransform[3])/adfResampleGeoTransform[5] + 0.5); 139 int mssEffectiveWidth = static_cast<int>((resampleEndXY[0] - adfResampleGeoTransform[0])/adfMssGeoTransform[1] + 0.5); 140 int mssEffectiveHeight = static_cast<int>((resampleEndXY[1] - adfResampleGeoTransform[3])/adfMssGeoTransform[5] + 0.5); 141 int panEffectiveWidth = resampleWidth; 142 int panEffectiveHeight = resampleHeight; 143 144 // 创建新数据集=======位置增益大小 145 int mssGainX = static_cast<int>((adfResampleGeoTransform[0] - adfMssGeoTransform[0])/adfMssGeoTransform[1] + 0.5); 146 int mssGainY = static_cast<int>((adfResampleGeoTransform[3] - adfMssGeoTransform[3])/adfMssGeoTransform[5] + 0.5); 147 int panGainX = static_cast<int>((adfResampleGeoTransform[0] - adfPanGeoTransform[0])/adfPanGeoTransform[1] + 0.5); 148 int panGainY = static_cast<int>((adfResampleGeoTransform[3] - adfPanGeoTransform[3])/adfPanGeoTransform[5] + 0.5); 149 150 151 // 创建新数据集=======创建文件 152 GDALDriver *poOutDriver = (GDALDriver*)GDALGetDriverByName("GTIFF"); 153 if(!poOutDriver){ 154 return -1; 155 } 156 GDALDataset *poOutDS = poOutDriver->Create(resamplefileName,resampleWidth, 157 resampleHeight,mssBandCount,mssDT,NULL); 158 //GDALDataset *poOutDS = poOutDriver->Create(resamplefileName,resampleWidth, 159 // resampleHeight,mssBandCount,GDT_Float32,NULL); 160 poOutDS->SetGeoTransform(adfResampleGeoTransform); 161 poOutDS->SetProjection(poPANDS->GetProjectionRef()); 162 163 int pBandMap[4] = {1,2,3,4}; 164 // 重采样核心代码============图像分块 165 int iNumRow = 256; 166 if(iNumRow > resampleHeight){ 167 iNumRow = 1; 168 } 169 int loopNum = (resampleHeight + iNumRow - 1)/iNumRow; //分块数 170 int nLineSpace,nPixSpace,nBandSpace; 171 nLineSpace = sizeof(float)*mssEffectiveWidth*mssBandCount; 172 nPixSpace = 0; 173 nBandSpace = sizeof(float)*mssEffectiveWidth; 174 175 // 重采样采样比例 176 float radioX = adfPanGeoTransform[1]/adfMssGeoTransform[1]; 177 float radioY = adfPanGeoTransform[5]/adfMssGeoTransform[5]; 178 179 int mssCurPosX = mssGainX; 180 int mssCurPosY = mssGainY; 181 int mssCurWidth = 0; 182 int mssCurHeight = 0; 183 184 // 重采样核心代码============ 185 // OpenCL部分 =============== 1 创建平台 186 cl_uint num_platforms; 187 cl_int ret = clGetPlatformIDs(0,NULL,&num_platforms); 188 if(ret != CL_SUCCESS || num_platforms < 1){ 189 printf("clGetPlatformIDs Error\n"); 190 return -1; 191 } 192 cl_platform_id platform_id = NULL; 193 ret = clGetPlatformIDs(1,&platform_id,NULL); 194 if(ret != CL_SUCCESS){ 195 printf("clGetPlatformIDs Error2\n"); 196 return -1; 197 } 198 199 // OpenCL部分 =============== 2 获得设备 200 cl_uint num_devices; 201 ret = clGetDeviceIDs(platform_id,CL_DEVICE_TYPE_GPU,0,NULL, 202 &num_devices); 203 if(ret != CL_SUCCESS || num_devices < 1){ 204 printf("clGetDeviceIDs Error\n"); 205 return -1; 206 } 207 cl_device_id device_id; 208 ret = clGetDeviceIDs(platform_id,CL_DEVICE_TYPE_GPU,1,&device_id,NULL); 209 if(ret != CL_SUCCESS){ 210 printf("clGetDeviceIDs Error2\n"); 211 return -1; 212 } 213 214 // OpenCL部分 =============== 3 创建Context 215 cl_context_properties props[] = {CL_CONTEXT_PLATFORM, 216 (cl_context_properties)platform_id,0}; 217 cl_context context = NULL; 218 context = clCreateContext(props,1,&device_id,NULL,NULL,&ret); 219 if(ret != CL_SUCCESS || context == NULL){ 220 printf("clCreateContext Error\n"); 221 return -1; 222 } 223 224 // OpenCL部分 =============== 4 创建Command Queue 225 cl_command_queue command_queue = NULL; 226 command_queue = clCreateCommandQueue(context,device_id,0,&ret); 227 if(ret != CL_SUCCESS || command_queue == NULL){ 228 printf("clCreateCommandQueue Error\n"); 229 return -1; 230 } 231 232 // OpenCL部分 =============== 6 创建编译Program 233 const char *strfile = "D:\\PIE3\\src\\Test\\TextOpecCLResample\\TextOpecCLResample\\ReSampleKernel.txt"; 234 size_t lenSource = 0; 235 char *kernelSource = LoadProgSource(strfile,"",&lenSource); 236 cl_program *programs = (cl_program *)malloc(loopNum*sizeof(cl_program)); 237 memset(programs,0,sizeof(cl_program)*loopNum); 238 239 cl_kernel *kernels = (cl_kernel*)malloc(loopNum*sizeof(cl_kernel)); 240 memset(kernels,0,sizeof(cl_kernel)*loopNum); 241 242 243 for(int i = 0;i<loopNum;i++){ 244 int tmpRowNum = iNumRow; 245 int startR = i*iNumRow; 246 int endR = startR + iNumRow - 1; 247 if(endR>resampleHeight -1){ 248 tmpRowNum = resampleHeight - startR; 249 //endR = startR + tmpRowNum - 1; 250 } 251 //计算读取的MSS影像区域大小 252 int mssCurWidth = mssEffectiveWidth; 253 int mssCurHeight = 0; 254 if(MethodType == 0) 255 mssCurHeight = int(tmpRowNum*radioY); 256 else if(MethodType == 1) 257 mssCurHeight = int(tmpRowNum*radioY)+1; 258 else if(MethodType == 2) 259 mssCurHeight = int(tmpRowNum*radioY)+2; 260 261 if(mssCurHeight + mssCurPosY > mssHeight - 1){ 262 mssCurHeight = mssHeight - mssCurPosY; 263 } 264 265 //创建数据 266 float *resampleBuf = (float *)malloc(sizeof(cl_float)*tmpRowNum*resampleWidth*mssBandCount); 267 float *mssBuf = (float *)malloc(sizeof(cl_float)*mssCurHeight*mssCurWidth*mssBandCount); 268 memset(resampleBuf,0,sizeof(cl_float)*tmpRowNum*resampleWidth*mssBandCount); 269 memset(mssBuf,0,sizeof(cl_float)*mssCurHeight*mssCurWidth*mssBandCount); 270 271 // 读取数据 272 poMSSDS->RasterIO(GF_Read,mssCurPosX,mssCurPosY,mssCurWidth,mssCurHeight, 273 mssBuf,mssCurWidth,mssCurHeight,GDT_Float32,mssBandCount,pBandMap,nPixSpace, 274 nLineSpace,nBandSpace); 275 276 if(MethodType == 0) 277 mssCurPosY += mssCurHeight; 278 else if(MethodType == 1) 279 mssCurPosY += mssCurHeight - 1; 280 else if(MethodType == 2) 281 mssCurPosY += mssCurHeight - 2; 282 283 // OpenCL部分 =============== 5 创建Memory Object 284 cl_mem mem_mss = NULL; 285 mem_mss = clCreateBuffer(context,CL_MEM_READ_WRITE | CL_MEM_USE_HOST_PTR, 286 sizeof(cl_float)*mssCurHeight*mssCurWidth*mssBandCount,mssBuf,&ret); 287 if(ret != CL_SUCCESS || NULL == mem_mss){ 288 printf("clCreateBuffer Error\n"); 289 return -1; 290 } 291 292 cl_mem mem_resample = NULL; 293 mem_resample = clCreateBuffer(context,CL_MEM_READ_WRITE | CL_MEM_USE_HOST_PTR, 294 sizeof(cl_float)*resampleWidth*tmpRowNum*mssBandCount,resampleBuf,&ret); 295 if(ret != CL_SUCCESS || NULL == mem_resample){ 296 printf("clCreateBuffer Error\n"); 297 return -1; 298 } 299 300 // OpenCL部分 =============== 6 创建编译Program 301 //const char *strfile = "D:\\PIE3\\src\\Test\\TextOpecCLResample\\TextOpecCLResample\\ReSampleKernel.txt"; 302 //size_t lenSource = 0; 303 //char *kernelSource = LoadProgSource(strfile,"",&lenSource); 304 //cl_program program = NULL; 305 programs[i] = clCreateProgramWithSource(context,1,(const char**)&kernelSource, 306 NULL,&ret); 307 if(ret != CL_SUCCESS || NULL == programs[i]){ 308 printf("clCreateProgramWithSource Error\n"); 309 return -1; 310 } 311 ret = clBuildProgram(programs[i],1,&device_id,NULL,NULL,NULL); 312 if(ret != CL_SUCCESS){ 313 char* build_log; 314 size_t log_size; 315 //查询日志的大小 316 clGetProgramBuildInfo(programs[i], device_id, CL_PROGRAM_BUILD_LOG, 0, NULL, &log_size); 317 build_log = new char[log_size+1]; 318 //获得编译日志信息 319 ret = clGetProgramBuildInfo(programs[i], device_id, CL_PROGRAM_BUILD_LOG, log_size, build_log, NULL); 320 build_log[log_size] = ‘\0‘; 321 printf("%s\n",build_log); 322 printf("编译失败!"); 323 delete []build_log; 324 return -1; 325 } 326 327 // OpenCL部分 =============== 7 创建Kernel 328 //cl_kernel kernel = NULL; 329 kernels[i] = clCreateKernel(programs[i],"ReSampleKernel",&ret); 330 if(ret != CL_SUCCESS || NULL == kernels[i]){ 331 printf("clCreateProgramWithSource Error\n"); 332 return -1; 333 } 334 335 // OpenCL部分 =============== 8 设置Kernel参数 336 ret = clSetKernelArg(kernels[i],0,sizeof(cl_mem),&mem_mss); 337 ret |= clSetKernelArg(kernels[i],1,sizeof(cl_mem),&mem_resample); 338 ret |= clSetKernelArg(kernels[i],2,sizeof(cl_int),&mssCurWidth); 339 ret |= clSetKernelArg(kernels[i],3,sizeof(cl_int),&mssCurHeight); 340 ret |= clSetKernelArg(kernels[i],4,sizeof(cl_int),&mssBandCount); 341 ret |= clSetKernelArg(kernels[i],5,sizeof(cl_int),&mssGainX); 342 ret |= clSetKernelArg(kernels[i],6,sizeof(cl_int),&mssGainY); 343 ret |= clSetKernelArg(kernels[i],7,sizeof(cl_int),&resampleWidth); 344 ret |= clSetKernelArg(kernels[i],8,sizeof(cl_int),&tmpRowNum); 345 ret |= clSetKernelArg(kernels[i],9,sizeof(cl_float),&radioX); 346 ret |= clSetKernelArg(kernels[i],10,sizeof(cl_float),&radioY); 347 ret |= clSetKernelArg(kernels[i],11,sizeof(cl_float),&dfSrcNoDataValue); 348 ret |= clSetKernelArg(kernels[i],12,sizeof(cl_int),&MethodType); 349 if(ret != CL_SUCCESS){ 350 printf("clSetKernelArg Error\n"); 351 return -1; 352 } 353 354 // OpenCL部分 =============== 9 设置Group Size 355 cl_uint work_dim = 2; 356 size_t global_work_size[] = {resampleWidth,tmpRowNum}; 357 size_t *local_work_size = NULL; 358 359 // OpenCL部分 =============== 10 执行内核 360 ret = clEnqueueNDRangeKernel(command_queue,kernels[i],work_dim,NULL,global_work_size, 361 local_work_size,0,NULL,NULL); 362 ret |= clFinish(command_queue); 363 if(ret != CL_SUCCESS){ 364 printf("clEnqueueNDRangeKernel Error\n"); 365 return -1; 366 } 367 368 // OpenCL部分 =============== 11 读取结果 369 370 resampleBuf = (float*)clEnqueueMapBuffer(command_queue,mem_resample,CL_TRUE,CL_MAP_READ | CL_MAP_WRITE, 371 0,sizeof(cl_float)*tmpRowNum*resampleWidth*mssBandCount,0,NULL,NULL,&ret); 372 //ret = clEnqueueReadBuffer(command_queue,mem_resample,CL_TRUE,0, 373 // sizeof(cl_float)*tmpRowNum*resampleWidth*mssBandCount,(void*)resampleBuf,0,NULL,NULL); 374 if(ret != CL_SUCCESS){ 375 printf("clEnqueueMapBuffer Error\n"); 376 return -1; 377 } 378 379 380 // 数据格式转换 381 long sz = tmpRowNum*resampleWidth*mssBandCount; 382 void *pBuf = NULL; 383 CPLErr err; 384 switch(mssDT){ 385 case GDT_Byte: 386 pBuf = new unsigned char[sz]; 387 if(!DataTypeTrans<unsigned char>(resampleBuf,(unsigned char*)pBuf,sz)) 388 { 389 printf("DataTypeTrans Error\n"); 390 return -1; 391 } 392 poOutDS->RasterIO(GF_Write,0,startR,resampleWidth,tmpRowNum,pBuf, 393 resampleWidth,tmpRowNum,mssDT,mssBandCount,NULL,nPixSpace,resampleWidth*mssBandCount*sizeof(unsigned char), 394 resampleWidth*sizeof(unsigned char)); 395 break; 396 case GDT_UInt16: 397 pBuf = new unsigned short int[sz]; 398 if(!DataTypeTrans<unsigned short int>(resampleBuf,(unsigned short int*)pBuf,sz)) 399 { 400 printf("DataTypeTrans Error\n"); 401 return -1; 402 } 403 err = poOutDS->RasterIO(GF_Write,0,startR,resampleWidth,tmpRowNum,pBuf, 404 resampleWidth,tmpRowNum,mssDT,mssBandCount,NULL,nPixSpace,resampleWidth*mssBandCount*sizeof(unsigned short int), 405 resampleWidth*sizeof(unsigned short int)); 406 break; 407 case GDT_Int16: 408 pBuf = new short int[sz]; 409 if(!DataTypeTrans<short int>(resampleBuf,(short int*)pBuf,sz)) 410 { 411 printf("DataTypeTrans Error\n"); 412 return -1; 413 } 414 poOutDS->RasterIO(GF_Write,0,startR,resampleWidth,tmpRowNum,pBuf, 415 resampleWidth,tmpRowNum,mssDT,mssBandCount,NULL,nPixSpace,resampleWidth*mssBandCount*sizeof(short int), 416 resampleWidth*sizeof(short int)); 417 break; 418 case GDT_UInt32: 419 pBuf = new unsigned int[sz]; 420 if(!DataTypeTrans<unsigned int>(resampleBuf,(unsigned int*)pBuf,sz)) 421 { 422 printf("DataTypeTrans Error\n"); 423 return -1; 424 } 425 poOutDS->RasterIO(GF_Write,0,startR,resampleWidth,tmpRowNum,pBuf, 426 resampleWidth,tmpRowNum,mssDT,mssBandCount,NULL,nPixSpace,resampleWidth*mssBandCount*sizeof(unsigned int), 427 resampleWidth*sizeof(unsigned int)); 428 break; 429 case GDT_Int32: 430 pBuf = new int[sz]; 431 if(!DataTypeTrans<int>(resampleBuf,(int*)pBuf,sz)) 432 { 433 printf("DataTypeTrans Error\n"); 434 return -1; 435 } 436 poOutDS->RasterIO(GF_Write,0,startR,resampleWidth,tmpRowNum,pBuf, 437 resampleWidth,tmpRowNum,mssDT,mssBandCount,NULL,nPixSpace,resampleWidth*mssBandCount*sizeof(int), 438 resampleWidth*sizeof(int)); 439 break; 440 case GDT_Float32: 441 pBuf = new float[sz]; 442 if(!DataTypeTrans<float>(resampleBuf,(float *)pBuf,sz)) 443 { 444 printf("DataTypeTrans Error\n"); 445 return -1; 446 } 447 poOutDS->RasterIO(GF_Write,0,startR,resampleWidth,tmpRowNum,pBuf, 448 resampleWidth,tmpRowNum,mssDT,mssBandCount,NULL,nPixSpace,resampleWidth*mssBandCount*sizeof(float), 449 resampleWidth*sizeof(float)); 450 break; 451 case GDT_Float64: 452 pBuf = new double[sz]; 453 if(!DataTypeTrans<double>(resampleBuf,(double *)pBuf,sz)) 454 { 455 printf("DataTypeTrans Error\n"); 456 return -1; 457 } 458 poOutDS->RasterIO(GF_Write,0,startR,resampleWidth,tmpRowNum,pBuf, 459 resampleWidth,tmpRowNum,mssDT,mssBandCount,NULL,nPixSpace,resampleWidth*mssBandCount*sizeof(double), 460 resampleWidth*sizeof(double)); 461 break; 462 } 463 delete []pBuf;pBuf = NULL; 464 free(mssBuf); 465 free(resampleBuf); 466 467 // OpenCL部分 =============== 12 释放资源 468 if(NULL != mem_mss) clReleaseMemObject(mem_mss); 469 if(NULL != mem_resample) clReleaseMemObject(mem_resample); 470 std::cout<<i<<std::endl; 471 } 472 // OpenCL部分 =============== 12 释放资源 473 int i = 0; 474 while(i < loopNum){ 475 if(NULL != kernels[i]) clReleaseKernel(kernels[i]); 476 if(NULL != programs[i]) clReleaseProgram(programs[i]); 477 i++; 478 } 479 480 if(NULL != command_queue) clReleaseCommandQueue(command_queue); 481 if(NULL != context) clReleaseContext(context); 482 GDALClose((GDALDatasetH)poPANDS); 483 GDALClose((GDALDatasetH)poMSSDS); 484 GDALClose((GDALDatasetH)poOutDS); 485 return 0; 486 } 487 488 489 490 491 492 #endif
GPU核函数代码如下：
1 #pragma OPENCL EXTENSION cl_amd_printf:enable 2 3 __kernel void ReSampleKernel(__global const float *mssData, 4 __global float *resampleData, 5 int mssWidth, 6 int mssHeight, 7 int mssBandCount, 8 int mssOffsetX, 9 int mssOffsetY, 10 int panWidth, 11 int panHeight, 12 float radioX, 13 float radioY, 14 float dfDstNoDataValue, 15 int MethodType) 16 { 17 int idx = get_global_id(1); // 采样行 18 int idy = get_global_id(0); // 采样列 19 float eps = 0.00001f; 20 if(idx < panHeight && idy < panWidth){ 21 // 找到对应的MSS像素位置 22 float curX = (float)idx * radioX; 23 float curY = (float)idy * radioY; 24 int tmpP = (int)curX*mssWidth*mssBandCount + (int)curY; 25 if(mssData[tmpP] == dfDstNoDataValue) 26 { 27 int i = 0; 28 while(i < mssBandCount){ 29 resampleData[idx*panWidth*mssBandCount+i*panWidth + idy] = dfDstNoDataValue; 30 i++; 31 } 32 return; 33 } 34 if(MethodType == 0){ // 最近邻 35 int nearX = (int)(curX + 0.5)>(int)curX?(int)(curX + 1):(int)curX; 36 int nearY = (int)(curY + 0.5)>(int)curY?(int)(curY + 1):(int)curY; 37 if(nearX >= mssHeight - 1){ 38 nearX = mssHeight - 1; 39 } 40 if(nearY >= mssWidth - 1){ 41 nearY = mssWidth - 1; 42 } 43 if(nearX < mssHeight && nearY < mssWidth){ 44 int i = 0; 45 while(i < mssBandCount){ 46 resampleData[idx*panWidth*mssBandCount+i*panWidth + idy] = 47 mssData[nearX*mssWidth*mssBandCount + i*mssWidth + nearY]; 48 i++; 49 } 50 } 51 } 52 if(MethodType == 1){ // 双线性 53 float dataX = curX - (int)curX; 54 float dataY = curY - (int)curY; 55 if(dataX < eps){ 56 dataX = 0.00001; 57 } 58 if(dataY < eps){ 59 dataY = 0.00001; 60 } 61 int preX = (int)curX; 62 int preY = (int)curY; 63 int postX = (int)curX + 1; 64 int postY = (int)curY + 1; 65 if(postX >= mssHeight - 1){ 66 postX = mssHeight - 1; 67 } 68 if(postY >= mssWidth - 1){ 69 postY = mssWidth - 1; 70 } 71 72 float Wx1 = 1 - dataX; 73 float Wx2 = dataX; 74 float Wy1 = 1 - dataY; 75 float Wy2 = dataY; 76 // 双线性差值核心代码 77 int i = 0; 78 while(i < mssBandCount){ 79 float pMssValue[4] = {0,0,0,0}; 80 pMssValue[0] = mssData[preX*mssWidth*mssBandCount + i*mssWidth + preY]; 81 pMssValue[1] = mssData[preX*mssWidth*mssBandCount + i*mssWidth + postY]; 82 pMssValue[2] = mssData[postX*mssWidth*mssBandCount + i*mssWidth + preY]; 83 pMssValue[3] = mssData[postX*mssWidth*mssBandCount + i*mssWidth + postY]; 84 resampleData[idx*panWidth*mssBandCount+i*panWidth + idy] = 85 Wy1*(Wx1*pMssValue[0] + Wx2*pMssValue[2]) + Wy2*(Wx1*pMssValue[1] + Wx2*pMssValue[3]); 86 i++; 87 } 88 } 89 if(MethodType == 2){ // 双三次卷积 90 float dataX = curX - (int)curX; 91 float dataY = curY - (int)curY; 92 //printf("dataX = %f dataY = %f\n",dataX,dataY); 93 int preX1 = (int)curX - 1; 94 int preX2 = (int)curX; 95 int postX1 = (int)curX + 1; 96 int postX2 = (int)curX + 2; 97 int preY1 = (int)curY - 1; 98 int preY2 = (int)curY; 99 int postY1 = (int)curY + 1; 100 int postY2 = (int)curY + 2; 101 if(preX1 < 0) preX1 = 0; 102 if(preY1 < 0) preY1 = 0; 103 if(postX1 > mssHeight - 1) postX1 = mssHeight - 1; 104 if(postX2 > mssHeight - 1) postX2 = mssHeight - 1; 105 if(postY1 > mssWidth - 1) postY1 = mssWidth - 1; 106 if(postY2 > mssWidth - 1) postY2 = mssWidth - 1; 107 108 float Wx1 = -1.0f*dataX + 2*dataX*dataX - dataX*dataX*dataX; 109 float Wx2 = 1 - 2*dataX*dataX + dataX*dataX*dataX; 110 float Wx3 = dataX + dataX*dataX - dataX*dataX*dataX; 111 float Wx4 = -1.0f*dataX*dataX + dataX*dataX*dataX; 112 float Wy1 = -1.0f*dataY + 2*dataY*dataY - dataY*dataY*dataY; 113 float Wy2 = 1 - 2*dataY*dataY + dataY*dataY*dataY; 114 float Wy3 = dataY + dataY*dataY - dataY*dataY*dataY; 115 float Wy4 = -1.0f*dataY*dataY + dataY*dataY*dataY; 116 117 //printf("preX1 = %d\n",preX1); 118 int i = 0; 119 while(i < mssBandCount){ 120 float pMssValue[16] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}; 121 pMssValue[0] = mssData[preX1*mssWidth*mssBandCount + i*mssWidth + preY1]; 122 pMssValue[1] = mssData[preX1*mssWidth*mssBandCount + i*mssWidth + preY2]; 123 pMssValue[2] = mssData[preX1*mssWidth*mssBandCount + i*mssWidth + postY1]; 124 pMssValue[3] = mssData[preX1*mssWidth*mssBandCount + i*mssWidth + postY2]; 125 126 pMssValue[4] = mssData[preX2*mssWidth*mssBandCount + i*mssWidth + preY1]; 127 pMssValue[5] = mssData[preX2*mssWidth*mssBandCount + i*mssWidth + preY2]; 128 pMssValue[6] = mssData[preX2*mssWidth*mssBandCount + i*mssWidth + postY1]; 129 pMssValue[7] = mssData[preX2*mssWidth*mssBandCount + i*mssWidth + postY2]; 130 131 pMssValue[8] = mssData[postX1*mssWidth*mssBandCount + i*mssWidth + preY1]; 132 pMssValue[9] = mssData[postX1*mssWidth*mssBandCount + i*mssWidth + preY2]; 133 pMssValue[10] = mssData[postX1*mssWidth*mssBandCount + i*mssWidth + postY1]; 134 pMssValue[11] = mssData[postX1*mssWidth*mssBandCount + i*mssWidth + postY2]; 135 136 pMssValue[12] = mssData[postX2*mssWidth*mssBandCount + i*mssWidth + preY1]; 137 pMssValue[13] = mssData[postX2*mssWidth*mssBandCount + i*mssWidth + preY2]; 138 pMssValue[14] = mssData[postX2*mssWidth*mssBandCount + i*mssWidth + postY1]; 139 pMssValue[15] = mssData[postX2*mssWidth*mssBandCount + i*mssWidth + postY2]; 140 141 resampleData[idx*panWidth*mssBandCount+i*panWidth + idy] = 142 Wy1*(Wx1*pMssValue[0] + Wx2*pMssValue[4] + Wx3*pMssValue[8] + Wx4*pMssValue[12])+ 143 Wy2*(Wx1*pMssValue[1] + Wx2*pMssValue[5] + Wx3*pMssValue[9] + Wx4*pMssValue[13])+ 144 Wy3*(Wx1*pMssValue[2] + Wx2*pMssValue[6] + Wx3*pMssValue[10] + Wx4*pMssValue[14])+ 145 Wy4*(Wx1*pMssValue[3] + Wx2*pMssValue[7] + Wx3*pMssValue[11] + Wx4*pMssValue[15]); 146 i++; 147 } 148 } 149 } 150 }
以上代码应该可以直接使用，欢迎大家一起交流探讨。
另外，我对GDAL、CPU和GPU版本的重采样算法效率进行了一下对比，GPU在三次卷积重采样算法上要明显的比CPU版本效率高很多。具体结果如下：
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原文地址：http://www.cnblogs.com/zyore2013/p/5974972.html
