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<DIV>Hi, </DIV>
<DIV> </DIV>
<DIV>I used GDAL to reproject the TM images, and the original projection of the
TM images was longitude/latitude WGS84, the final projection was UTM 51. The
codes I used is as following:</DIV>
<DIV> </DIV>
<DIV>void doCore()<BR>{</DIV>
<DIV> </DIV>
<DIV> GDALDataType eDT;<BR> GDALDataset *hDstDS;<BR> GDALDataset
*hSrcDS;</DIV>
<DIV> </DIV>
<DIV> GDALAllRegister();</DIV>
<DIV> </DIV>
<DIV> // cache Max<BR> GDALSetCacheMax(1024*1024*1024);</DIV>
<DIV> </DIV>
<DIV> // open file<BR> hSrcDS = (GDALDataset *)GDALOpen(
"G:\\Data\\TM\\0_Water_Vapor_Near_Infrared.tif", GA_ReadOnly
);<BR> CPLAssert( hSrcDS != NULL );</DIV>
<DIV> </DIV>
<DIV> GDALRasterBand *iBand1 = hSrcDS->GetRasterBand(1); </DIV>
<DIV> </DIV>
<DIV> const char *pszSrcWKT;<BR> char *pszDstWKT =
NULL;<BR> pszSrcWKT = GDALGetProjectionRef( hSrcDS );<BR> CPLAssert(
pszSrcWKT != NULL && strlen(pszSrcWKT) > 0 );</DIV>
<DIV> </DIV>
<DIV><BR> // set UTM<BR> OGRSpatialReference
oSRS;<BR> oSRS.SetUTM(51,
TRUE);<BR> oSRS.SetWellKnownGeogCS("WGS84");<BR> oSRS.exportToWkt(
&pszDstWKT );</DIV>
<DIV> </DIV>
<DIV> void *hTransformArg;<BR> hTransformArg =
GDALCreateGenImgProjTransformer( hSrcDS, pszSrcWKT, NULL, pszDstWKT, FALSE, 0, 1
);<BR> CPLAssert( hTransformArg != NULL );</DIV>
<DIV> </DIV>
<DIV> // calculate 6 parameters <BR> double
adfDstGeoTransform[6];<BR> int nPixels=0, nLines=0;<BR> CPLErr
eErr;<BR> eErr = GDALSuggestedWarpOutput( hSrcDS, GDALGenImgProjTransform,
hTransformArg, adfDstGeoTransform, &nPixels, &nLines
);<BR> CPLAssert( eErr == CE_None
);<BR> GDALDestroyGenImgProjTransformer(hTransformArg);</DIV>
<DIV> </DIV>
<DIV><BR> // create out file<BR> eDT =
GDALDataType(iBand1->GetRasterDataType());<BR> GDALDriver *hDriver =
(GDALDriver *)GDALGetDriverByName( "GTiff" );<BR> CPLAssert( hDriver !=
NULL );<BR> hDstDS = (GDALDataset *)GDALCreate( hDriver,
"G:\\data\\TM\\out.tif", nPixels, nLines, GDALGetRasterCount(hSrcDS), eDT, NULL
);<BR> CPLAssert( hDstDS != NULL );</DIV>
<DIV> </DIV>
<DIV> // write projection
info<BR> hDstDS->SetProjection(pszDstWKT);<BR> hDstDS->SetGeoTransform(adfDstGeoTransform);</DIV>
<DIV> </DIV>
<DIV> // create warp info <BR> GDALWarpOptions *psWarpOptions =
GDALCreateWarpOptions();</DIV>
<DIV> </DIV>
<DIV> psWarpOptions->dfWarpMemoryLimit =
1024*1024*1024;<BR> psWarpOptions->hSrcDS =
hSrcDS;<BR> psWarpOptions->hDstDS = hDstDS;</DIV>
<DIV> </DIV>
<DIV> psWarpOptions->nBandCount =
1;<BR> psWarpOptions->panSrcBands = (int *) CPLMalloc(sizeof(int)
);<BR> psWarpOptions->panSrcBands[0] =
1;<BR> psWarpOptions->panDstBands = (int *) CPLMalloc(sizeof(int)
);<BR> psWarpOptions->panDstBands[0] = 1;</DIV>
<DIV> </DIV>
<DIV> psWarpOptions->pfnProgress = GDALTermProgress;</DIV>
<DIV> </DIV>
<DIV> psWarpOptions->pTransformerArg = GDALCreateGenImgProjTransformer(
hSrcDS, pszSrcWKT, hDstDS, pszDstWKT, FALSE, 0, 1
);<BR> psWarpOptions->pfnTransformer = GDALGenImgProjTransform;</DIV>
<DIV> </DIV>
<DIV> // do it <BR> GDALWarpOperation
oOPeration;<BR> oOPeration.Initialize(psWarpOptions);<BR> oOPeration.ChunkAndWarpMulti(0,
0, nPixels, nLines);</DIV>
<DIV> </DIV>
<DIV> GDALDestroyGenImgProjTransformer(psWarpOptions->pTransformerArg);<BR> GDALDestroyWarpOptions(
psWarpOptions );<BR> CPLFree(pszDstWKT);</DIV>
<DIV> </DIV>
<DIV> GDALClose(hDstDS);<BR> GDALClose(hSrcDS);<BR>}</DIV>
<DIV> </DIV>
<DIV>However, the time which the codes spent to process one image is about 70
seconds in VS 2010 x64 release, and in ENVI/IDL, it was only spend 45
seconds. So, I am wonder whether something wrong in my codes? Thanks!</DIV>
<DIV> </DIV>
<DIV>Yours,</DIV>
<DIV>Xia Lang</DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV style="FONT-SIZE: 10pt; FONT-FAMILY: Verdana; COLOR: #c0c0c0">
<DIV align=left>2015-05-18</DIV>
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<SPAN id=_FlashSignName>xialang2012</SPAN> </DIV></STATIONERY></BODY></HTML>