C++ GDALRasterBand::ReadBlock方法代码示例

 virtual CPLErr IReadBlock( int nBlockXOff, int nBlockYOff, void * pData )
 {
     return poUnderlyingBand->ReadBlock(nBlockXOff, nBlockYOff, pData);
 }

//.........这里部分代码省略.........
		{
			Create(iXSize, iYSize, 32);
		}
		else if (iRasterCount == 3 || bColorPalette)
		{
			Create(iXSize, iYSize, 24);
		}
		else if (iRasterCount == 1)
			Create(iXSize, iYSize, 8);

		// Read the data
#if LOG_IMAGE_LOAD
		VTLOG("Reading the image data (%d x %d pixels)\n", iXSize, iYSize);
#endif

		int x, y;
		int ixBlock, iyBlock;
		int nxValid, nyValid;
		int iY, iX;
		RGBi rgb;
		RGBAi rgba;
		if (iRasterCount == 1)
		{
			GDALColorEntry Ent;
			for (iyBlock = 0; iyBlock < nyBlocks; iyBlock++)
			{
				if (progress_callback != NULL)
					progress_callback(iyBlock * 100 / nyBlocks);

				y = iyBlock * yBlockSize;
				for (ixBlock = 0; ixBlock < nxBlocks; ixBlock++)
				{
					x = ixBlock * xBlockSize;
					Err = pBand->ReadBlock(ixBlock, iyBlock, pScanline);
					if (Err != CE_None)
						throw "Problem reading the image data.";

					// Compute the portion of the block that is valid
					// for partial edge blocks.
					if ((ixBlock+1) * xBlockSize > iXSize)
						nxValid = iXSize - ixBlock * xBlockSize;
					else
						nxValid = xBlockSize;

					if( (iyBlock+1) * yBlockSize > iYSize)
						nyValid = iYSize - iyBlock * yBlockSize;
					else
						nyValid = yBlockSize;

					for( iY = 0; iY < nyValid; iY++ )
					{
						for( iX = 0; iX < nxValid; iX++ )
						{
							if (bColorPalette)
							{
								pTable->GetColorEntryAsRGB(pScanline[iY * xBlockSize + iX], &Ent);
								rgb.r = (uchar) Ent.c1;
								rgb.g = (uchar) Ent.c2;
								rgb.b = (uchar) Ent.c3;
								SetPixel24(x + iX, y + iY, rgb);
							}
							else
								SetPixel8(x + iX, y + iY, pScanline[iY * xBlockSize + iX]);
						}
					}
				}

	bool DEM::load(const std::string& filename) {
		GDALAllRegister();

		GDALDataset* poDS;
		poDS = (GDALDataset*)GDALOpenEx(filename.c_str(), GDAL_OF_RASTER, NULL, NULL, NULL);
		if (poDS == NULL) return false;

		double adfGeoTransform[6];
		if (poDS->GetGeoTransform(adfGeoTransform) == CE_None) {
			origin.x = adfGeoTransform[0];
			origin.y = adfGeoTransform[3];

			pixelSize.x = adfGeoTransform[1];
			pixelSize.y = abs(adfGeoTransform[5]);
		}

		width = poDS->GetRasterXSize() * pixelSize.x;
		height = poDS->GetRasterYSize() * pixelSize.y;
		data.resize(width * height);
		min_val = std::numeric_limits<float>::max();
		max_val = -std::numeric_limits<float>::max();

		// bandが存在しない場合は、エラー
		if (poDS->GetRasterCount() == 0) return false;

		// 最初のbandのみを読み込む。複数bandは未対応
		GDALRasterBand* poBand = poDS->GetRasterBand(1);

		int nBlockXSize, nBlockYSize;
		poBand->GetBlockSize(&nBlockXSize, &nBlockYSize);
		//printf("Block=%dx%d Type=%s, ColorInterp=%s\n", nBlockXSize, nBlockYSize, GDALGetDataTypeName(poBand->GetRasterDataType()), GDALGetColorInterpretationName(poBand->GetColorInterpretation()));

		// 最低、最高の値を取得
		int bGotMin, bGotMax;
		double adfMinMax[2];
		adfMinMax[0] = poBand->GetMinimum(&bGotMin);
		adfMinMax[1] = poBand->GetMaximum(&bGotMax);
		if (!(bGotMin && bGotMax)) GDALComputeRasterMinMax((GDALRasterBandH)poBand, TRUE, adfMinMax);
		//printf("Min=%.3fd, Max=%.3f\n", adfMinMax[0], adfMinMax[1]);
		min_val = adfMinMax[0];
		max_val = adfMinMax[1];
			
		//int nXSize = poBand->GetXSize();
		//int nYSize = poBand->GetYSize();

		int nXBlocks = (poBand->GetXSize() + nBlockXSize - 1) / nBlockXSize;
		int nYBlocks = (poBand->GetYSize() + nBlockYSize - 1) / nBlockYSize;
		float *pData = (float *)CPLMalloc(sizeof(float*) * nBlockXSize * nBlockYSize);
		for (int iYBlock = 0; iYBlock < nYBlocks; iYBlock++) {
			for (int iXBlock = 0; iXBlock < nXBlocks; iXBlock++) {
				int nXValid, nYValid;

				poBand->ReadBlock(iXBlock, iYBlock, pData);

				// Compute the portion of the block that is valid
				// for partial edge blocks.
				if ((iXBlock + 1) * nBlockXSize > poBand->GetXSize())
					nXValid = poBand->GetXSize() - iXBlock * nBlockXSize;
				else
					nXValid = nBlockXSize;
				if ((iYBlock + 1) * nBlockYSize > poBand->GetYSize())
					nYValid = poBand->GetYSize() - iYBlock * nBlockYSize;
				else
					nYValid = nBlockYSize;

				for (int iY = 0; iY < nYValid; iY++) {
					for (int iX = 0; iX < nXValid; iX++) {
						float val;
						if (pData[iY * nBlockXSize + iX] > max_val) {
							val = max_val;
						}
						else if (pData[iY * nBlockXSize + iX] < min_val) {
							val = min_val;
						}
						else {
							val = pData[iY * nBlockXSize + iX];
						}

						for (int y = 0; y < pixelSize.y; ++y) {
							for (int x = 0; x < pixelSize.x; ++x) {
								data[((iYBlock * nBlockYSize + iY) * pixelSize.y + y) * width + (iXBlock * nBlockXSize + iX) * pixelSize.x + x] = val;
							}
						}
						
					}
				}
			}
		}

		GDALClose(poDS);

		return true;
	}