gdal__alg_8h.html

gdal库的学习文档

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<p>
Perform approximate transformation.<p>
Actually performs the approximate transformation described in <a class="el" href="gdal__alg_8h.html#4ec403b75384f0a71130eb009078426f">GDALCreateApproxTransformer()</a>. This function matches the <a class="el" href="gdal__alg_8h.html#9ad4227ec5fd5b70637eeb6996172318">GDALTransformerFunc()</a> signature. Details of the arguments are described there. 
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<a class="anchor" name="be2846ac3a350c24f07dc9ceac8f4d14"></a><!-- doxytag: member="gdal_alg.h::GDALChecksumImage" ref="be2846ac3a350c24f07dc9ceac8f4d14" args="(GDALRasterBandH hBand, int nXOff, int nYOff, int nXSize, int nYSize)" -->
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          <td class="memname">int GDALChecksumImage           </td>
          <td>(</td>
          <td class="paramtype">GDALRasterBandH&nbsp;</td>
          <td class="paramname"> <em>hBand</em>, </td>
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<p>
Compute checksum for image region.<p>
Computes a 16bit (0-65535) checksum from a region of raster data on a GDAL supported band. Floating point data is converted to 32bit integer so decimal portions of such raster data will not affect the checksum. Real and Imaginary components of complex bands influence the result.<p>
<dl compact><dt><b>Parameters:</b></dt><dd>
  <table border="0" cellspacing="2" cellpadding="0">
    <tr><td valign="top"></td><td valign="top"><em>hBand</em>&nbsp;</td><td>the raster band to read from. </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>nXOff</em>&nbsp;</td><td>pixel offset of window to read. </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>nYOff</em>&nbsp;</td><td>line offset of window to read. </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>nXSize</em>&nbsp;</td><td>pixel size of window to read. </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>nYSize</em>&nbsp;</td><td>line size of window to read.</td></tr>
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<dl class="return" compact><dt><b>Returns:</b></dt><dd>Checksum value. </dd></dl>

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<a class="anchor" name="61e48f88c3b4b3cf7957c61dc7bd1ead"></a><!-- doxytag: member="gdal_alg.h::GDALComputeMedianCutPCT" ref="61e48f88c3b4b3cf7957c61dc7bd1ead" args="(GDALRasterBandH hRed, GDALRasterBandH hGreen, GDALRasterBandH hBlue, int(*pfnIncludePixel)(int, int, void *), int nColors, GDALColorTableH hColorTable, GDALProgressFunc pfnProgress, void *pProgressArg)" -->
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          <td class="memname">int GDALComputeMedianCutPCT           </td>
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          <td class="paramtype">GDALRasterBandH&nbsp;</td>
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<p>
Compute optimal PCT for RGB image.<p>
This function implements a median cut algorithm to compute an "optimal" pseudocolor table for representing an input RGB image. This PCT could then be used with <a class="el" href="gdal__alg_8h.html#284dbcc27295b7e678b1f7d4fa1506cb">GDALDitherRGB2PCT()</a> to convert a 24bit RGB image into an eightbit pseudo-colored image.<p>
This code was based on the tiffmedian.c code from libtiff (www.libtiff.org) which was based on a paper by Paul Heckbert:<p>
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 *   "Color  Image Quantization for Frame Buffer Display", Paul
 *   Heckbert, SIGGRAPH proceedings, 1982, pp. 297-307.
 * </pre></div><p>
The red, green and blue input bands do not necessarily need to come from the same file, but they must be the same width and height. They will be clipped to 8bit during reading, so non-eight bit bands are generally inappropriate.<p>
<dl compact><dt><b>Parameters:</b></dt><dd>
  <table border="0" cellspacing="2" cellpadding="0">
    <tr><td valign="top"></td><td valign="top"><em>hRed</em>&nbsp;</td><td>Red input band. </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>hGreen</em>&nbsp;</td><td>Green input band. </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>hBlue</em>&nbsp;</td><td>Blue input band. </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>pfnIncludePixel</em>&nbsp;</td><td>function used to test which pixels should be included in the analysis. At this time this argument is ignored and all pixels are utilized. This should normally be NULL. </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>nColors</em>&nbsp;</td><td>the desired number of colors to be returned (2-256). </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>hColorTable</em>&nbsp;</td><td>the colors will be returned in this color table object. </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>pfnProgress</em>&nbsp;</td><td>callback for reporting algorithm progress matching the GDALProgressFunc() semantics. May be NULL. </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>pProgressArg</em>&nbsp;</td><td>callback argument passed to pfnProgress.</td></tr>
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<dl class="return" compact><dt><b>Returns:</b></dt><dd>returns CE_None on success or CE_Failure if an error occurs. </dd></dl>

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<a class="anchor" name="ceaf98ad40f159cbfb626988c054c085"></a><!-- doxytag: member="gdal_alg.h::GDALContourGenerate" ref="ceaf98ad40f159cbfb626988c054c085" args="(GDALRasterBandH hBand, double dfContourInterval, double dfContourBase, int nFixedLevelCount, double *padfFixedLevels, int bUseNoData, double dfNoDataValue, void *hLayer, int iIDField, int iElevField, GDALProgressFunc pfnProgress, void *pProgressArg)" -->
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          <td class="memname">CPLErr GDALContourGenerate           </td>
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