Syntax

   FACTORY_DEF <ReaderKeyword> VectorOnRasterOverlayFactory
   [FACTORY_NAME <factory name>] 
   [INPUT (RASTER|VECTOR) FEATURE_TYPE <feature type>
      [<attribute name> <attribute value>]*
      [<feature function>]*]* 
   ACTION <processing type> 
   [INTERPOLATION_TYPE (nearestneighbor|bilinear|bicubic|average4|average16)] 
   [GROUP_BY [<attribute name>]+]*
   [FLUSH_WHEN_GROUPS_CHANGE (Yes|No)]
   [OUTPUT POINT
      FEATURE_TYPE <feature type>
      [<attribute name> <attribute value>]*
      [<feature function>]*]* 

Overview

   This factory was designed to be used in situations where processing is done 
   with a single raster and many vectors. The processing pattern is defined as 
   follows: for each group, incoming valid vector features are stored until a 
   reference raster is received for this group. Immediately following the 
   reception of this raster, any stored vectors are processed using the raster. 
   The vectors that come after reception of the raster are processed as they are 
   received. Multiple rasters entering the factory in the same group will 
   generate an error.

   The processing that will take place depends on the value specified for the 
   ACTION parameter. However, every scenario will involve outputting one vector 
   feature for every vector feature that the factory receives. A single 
   different raster may be used for every individual group of incoming features. 
   The GROUP_BY parameter should be used for the purpose of defining such 
   feature groups.

   Currently, the factory supports only the following ACTION:

   RETRIEVE_BAND_AND_PALETTE_VALUES

   In this mode, the factory requires points as input vectors. For each input 
   point, a point is output which contains the attributes from the input point 
   and reference raster, as well as the band and palette value(s) at the 
   location of the point. An instance of the following list attributes will be 
   created for each band/palette on the raster:

      _band{}.value 
      _band{}.palette{}.value 

   When used in this mode, the The INTERPOLATION_TYPE parameter specifies the 
   interpolation method to be used when retrieving raster values from points. 
   Nearest Neighbor interpolation is the fastest and least accurate, while 
   Bilinear and Bicubic are slower but will weight surrounding data values into 
   the final result. Average 4 and Average 16 have a performance similar to 
   Bilinear and are useful for numeric rasters such as DEMs.
      
Output Tags

   POINT 
   
      The vector created for each input vector feature will be output via the 
      port associated with this tag. 
      
         Note: The output features will contain any attributes that the 
         corresponding input vector features had, as well as attributes 
         contained on the reference input raster.