Syntax

   FACTORY_DEF <ReaderKeyword> DEMDistanceFactory
   [FACTORY_NAME <factory name>] 
   [INPUT (REF_RASTER|VECTOR) FEATURE_TYPE <feature type>
      [<attribute name> <attribute value>]*
      [<feature function>]*]* 
   [REJECT_INVALID_GEOM <Yes|No>]
   ACTION DEM_DIST 
   [GROUP_BY [<field name>]+]*
   [OUTPUT RASTER
      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.

   The processing that will take place depends on the value specified for the 
   ACTION parameter. However, every scenario will involve outputting one raster 
   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.

   When REJECT_INVALID_GEOM is Yes, the factory will output invalid features to
   Rejected port.

   Currently, the factory supports only the following ACTION:

   DEM_DIST 

      In this mode, the factory requires three-dimensional line segments as input 
      vectors, and numeric Digital Elevation Model (DEM) formats as input rasters. 
      For each 3D line segment, a numeric DEM raster is output. The data contained 
      in each cell of each output DEM is the shortest 3D distance from the 
      corresponding cell of the input DEM to the line segment being considered.

Assumptions

   For the DEM_DIST processing type, incoming line features must be three-
   dimensional. The incoming raster feature must contain valid elevation data. 
   The factory will produce output data that will only be accessible using 
   numeric, continuous data calls.
   
Output Tags

   The DEMDistanceFactory supports the following output tag.
   
   RASTER   
   
      The raster created for each 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, with the exception of the 
         fme_type and fme_geometry attributes (in dem_dist processing mode). 
         Attributes contained on the reference input raster will not be present 
         on output features.

   REJECTED

      2D lines and extra reference DEMs go to this port.

Keywords

   PRESERVE_ORDER

      If Yes, it uses the backwards compatibility case:
      Since we are getting features from the beginning of the stash
      with IFMEFeatureQueue->getNextFeature(), but the old way was
      from the end of the stash, this step is to reverse order for
      older workspaces, so that the output will remain the same
      PR#71303

TO BE RESOLVED
   
   REF_RASTER and VECTOR input tags added to Syntax section above, but not 
   documented.