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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta http-equiv="Content-Type" content="text/html;charset=iso-8859-1"><title>GDAL: gdaladdo</title><link href="doxygen.css" rel="stylesheet" type="text/css"><link href="tabs.css" rel="stylesheet" type="text/css"></head><body><!-- Generated by Doxygen 1.5.1 --><div class="tabs"> <ul> <li><a href="index.html"><span>Main Page</span></a></li> <li><a href="annotated.html"><span>Classes</span></a></li> <li><a href="files.html"><span>Files</span></a></li> <li><a href="pages.html"><span>Related Pages</span></a></li> </ul></div><h1><a class="anchor" name="gdaladdo">gdaladdo</a></h1>builds or rebuilds overview images<p> Usage: <p><div class="fragment"><pre class="fragment">gdaladdo [-r {nearest,average,average_mp,average_magphase,mode}] filename levels</pre></div><p>The gdaladdo utility can be used to build or rebuild overview images for most supported file formats with one over several downsampling algorithms.<p><dl><dt><b>-r</b> <em>{nearest,average,average_mp,average_magphase,mode}</em>:</dt><dd>Select a resampling algorithm. </dd><dt><em>filename</em>:</dt><dd>The file to build overviews for. </dd><dt><em>levels</em>:</dt><dd>A list of integral overview levels to build. </dd></dl><p><em>Mode</em> is not actually implemented, and <em>average_mp</em> is unsuitable for use. <em>Average_magphase</em> averages complex data in mag/phase space. <em>Nearest</em> and <em>average</em> are applicable to normal image data. <em>Nearest</em> applies a nearest neighbour (simple sampling) resampler, while <em>average</em> computes the average of all non-NODATA contributing pixels.<p>Selecting a level value like <em>2</em> causes an overview level that is 1/2 the resolution (in each dimension) of the base layer to be computed. If the file has existing overview levels at a level selected, those levels will be recomputed and rewritten in place.<p>Some format drivers do not support overviews at all. Many format drivers store overviews in a secondary file with the extension .ovr that is actually in TIFF format. The GeoTIFF driver stores overviews internally to the file operated on.<p>Overviews created in TIFF format may be compressed using the COMPRESS_OVERVIEW configuration option. All compression methods, supported by the GeoTIFF driver, available here. (eg --config COMPRESS_OVERVIEW DEFLATE)<p>Most drivers also support an alternate overview format using Erdas Imagine format. To trigger this use the USE_RRD=YES configuration option. This will place the overviews in an associated .aux file suitable for direct use with Imagine or ArcGIS as well as GDAL applications. (eg --config USE_RRD YES)<p> Example:<p>Create overviews, embedded in the supplied TIFF file:<p><div class="fragment"><pre class="fragment">gdaladdo -r average abc.tif 2 4 8 16</pre></div><p>Create an external compressed GeoTIFF overview file from the ERDAS .IMG file:<p><div class="fragment"><pre class="fragment">gdaladdo --config COMPRESS_OVERVIEW DEFLATE erdas.img 2 4 8 16</pre></div><p>Create an Erdas Imagine format overviews for the indicated JPEG file:<p><div class="fragment"><pre class="fragment">gdaladdo --config USE_RRD YES airphoto.jpg 3 9 27 81</pre></div> <hr>Generated for GDAL by <a href="http://www.doxygen.org/index.html"><img src="doxygen.png" alt="doxygen" align="middle" border="0"></a> 1.5.1.</body></html>⌨️ 快捷键说明
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