Changes between Version 2 and Version 3 of RasterQuery


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Timestamp:
Jan 29, 2009, 12:02:37 PM (15 years ago)
Author:
jmckenna
Comment:

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  • RasterQuery

    v2 v3  
    55== General Approach ==
    66
    7 Raster query support is setup to return a set of request result "shapes" for each pixel matching the query. In MapServer CGI, normal template substitution is done. In !MapScript the normal mechanisms for reading a query result can be applied.
     7Raster query support is setup to return a set of request result "shapes" for each pixel matching the query. In !MapServer CGI, normal template substitution is done. In !MapScript the normal mechanisms for reading a query result can be applied.
    88
    99Currently !QueryByPoint (with single or multiple modes), !QueryByRect and !QueryByShape are supported. Care should be taken to avoid providing a large query area (selecting alot of pixels) as each selected pixel requires over 100 bytes of memory for temporary caching. The RASTER_QUERY_MAX_RESULT PROCESSING item can be used to restrict the maximum number of query results that will be returned. The default is one million which would take on the order of 100MB of RAM.
    … …  
    6464== Working Notes ==
    6565
    66     * Note that WMS GetFeatureInfo requests work against raster layers!
     66    * Note that WMS !GetFeatureInfo requests work against raster layers!
    6767    * Currently scaling is not applied to non-eight bit values in before computing class or color. Thus class, red, green and blue results may be a little or alot wrong in some circumstances. See
    6868    * The _msQueryByIndex(), msQueryByIndexAdd(), msQueryByAttributes() and msQueryByFeatures() are not supported for rasters. I don't really understand what they are or what they do.