Syntax

   FACTORY_DEF <ReaderKeyword> RasterMergerFactory
   [FACTORY_NAME <factory name>]
   [INPUT FEATURE_TYPE <factory type>
      [<attribute name> <attribute value>]*
      [<feature function>]*]*
   [COUNT_ATTRIBUTE <attribute name>]*
   [ACCUMULATE_ATTRIBUTES (yes|no|none|all|one)]
   [REJECT_INVALID_FEATURES (yes|no)]
   [LIST_NAME <list name>{}]
   [LIST_ATTRS_TO_INCLUDE [<attrNameToIncludeInList>]* ]
   [LIST_ATTRS_TO_INCLUDE_MODE (ALL|SELECTED)]
   [GROUP_BY [<attribute name>]+]*
   [FLUSH_WHEN_GROUPS_CHANGE (Yes|No)]
   [OUTPUT MERGED FEATURE_TYPE <feature type>
      [<attribute name> <attribute value>]*
      [<feature function>]*]*

Overview

   This factory is used to merge a collection of overlapping input raster 
   features into a single raster feature. The factory accepts a number of input 
   raster features, each of which has one or more bands. The bands are removed 
   from the input features and appended to a single output raster feature. The 
   order of the input features and the order of the bands of the input features 
   both determine the order of the bands in the output feature.

   The input features may be partitioned into groups based on attribute values 
   using the GROUP_BY clause and one raster feature is produced for each group. 
   If the GROUP_BY clause is not specified, then all input features will be 
   processed together and a single raster feature will be produced.

   The properties of each raster within a group, such as the number of rows and 
   columns, must match for the processing to proceed successfully. Each raster 
   within a group must also overlap identically.

   If the optional COUNT_ATTRIBUTE clause is given, a new attribute will be 
   created on every output feature, containing the number of input features that 
   were combined to form the output. If grouped, the output feature's count 
   attribute will have the number of input features that merged within its 
   group.

   If yes or all is specified for the ACCUMULATE_ATTRIBUTES clause, the attributes of 
   each input feature are merged onto the feature being output. If grouped, the 
   attributes of each input feature within a group are merged onto the group's 
   output feature. If no or none is specified for the clause, no user attributes will
   be carried across from the input features to the output features. If one is specified
   for the clause, user attributes only from one input feature will be on the output
   feature.

   The REJECT_INVALID_FEATURES clause specifies whether the factory will fail
   upon being supplied invalid features or output them to the <REJECTED> port.

   The optional LIST_NAME clause is used to associate attributes with incoming feature.
   When the output feature is created, all attributes of
   each feature joining the output are added as members of the specified
   attribute list. The index in the list corresponds to the index of the
   feature's geometry in the aggregate.

   The optional LIST_ATTRS_TO_INCLUDE_MODE will specify if ALL attributes should be added to
   a list, or if only the SELECTED attributes (specified with the LIST_ATTRS_TO_INCLUDE clause)
   should be added to the list.  If this value is not specified, it defaults to ALL.

   This factory accepts only features that have raster geometries and is 
   unaffected by raster band and/or palette sub-selection.

Output Tags

   The RasterMergerFactory supports the following output tag.
   
   MERGED   
   
      The output feature created by merging the input features.

   <REJECTED>

      The output feature that is deemed to be invalid input for any of the
      following reasons:
         - The feature does not have compatible geometry
         - The input rasters have mismatched properties