Syntax FACTORY_DEF PolygonDissolveFactory [FACTORY_NAME ] [INPUT FEATURE_TYPE [ ]* []*]* [GROUP_BY []+]* [PRE_BUFFER buffer_amount stroking_density cap_style [buffer_style]] [DISSOLVE_MODE [(GEOS|FME)] [NON_OVERLAPPING_INPUT [(yes|no)] [ACCUM_INPUT_ATTRS [(yes|no)] [SUM_FIELDS []+] [AVERAGE_FIELDS []+] [WEIGHTED_AVERAGE_FIELDS []+] [DISSOLVE_COUNT_ATTRIBUTE ] [LIST_NAME ] [MODE (QUICK|COMPLETE)] [OUTPUT (POLYGON|INTERIOR_LINE|NON_POLYGON|REJECTED) FEATURE_TYPE [ ]* []*]* Overview This factory accepts two-dimensional polygonal features, including donuts, and outputs dissolved polygons. Dissolved polygons are formed when shared edges and interior edges between adjacent polygons are removed. Note: If the FME_GEOMETRY_HANDLING directive is set to "yes" in the mapping file, ellipses are accepted as polygonal features; they are otherwise output untouched via the REJECTED feature output tag. Dissolved polygons are output via the AREA output tag. Non-polygonal input features are output untouched via the REJECTED feature output tag. If the OUTPUT INTERIOR_LINE clause is specified and DISSOLVE_MODE is set to FME, then line segments from input polygons that are not part of the output polygons will be output via the INTERIOR_LINE output tag. Computing interior lines is an expensive operation and should only be specified if these lines are necessary. Note: The INTERIOR_LINE keyword has non-standard behaviour within FME: the keyword is only respected when DISSOLVE_MODE is set to FME. The input polygons may be partitioned into groups for dissolving by using the GROUP_BY clause. If the GROUP_BY clause is not specified, then all input features are processed together. The GROUP_BY clause enables a single factory to dissolve several sets of potentially overlapping polygons. The GROUP_BY attributes are carried across from the input features to the output features. The PRE_BUFFER clause allows the factory to buffer before the dissolution step. If a positive (negative) buffer_amount is specified, the input feature is expanded (shrunk). A buffer_amount of 0 will leave the input geometry unmodified. As stroking_density increases in value, the smoothness of the arc connectors increases. Please supply only positive integer values. When buffering both sides of a line (buffer_style = FULL, which is default), there is the additional concept of end caps. Think of end caps as little caps worn by the two ends of a buffered line. These caps may be round or square. It is also possible for the buffered area not to wear any caps. Thus, possible values for cap_style are CAP_ROUND (round), CAP_PROJECTING (square), or CAP_BUTT (none). The DISSOLVE_MODE clause specifies the mode in which the dissolver operates. GEOS mode can be expected to be orders of magnitude faster than FME mode, but does not output interior lines, drops measures, and strokes arcs. FME mode, on the other hand, outputs interior lines, and preserves measures and arcs. On large input datasets, GEOS mode is recommended, as it can be orders of magnitude faster than FME mode. NON_OVERLAPPING_INPUT clause is only processed if the DISSOLVE_MODE is set to FME. If the NON_OVERLAPPING_INPUT clause is specified with an argument of "no", then for any two areas to be dissolved together, they must share a common boundary with identical vertices. If the argument to this clause contradicts the input, the factory will have undefined behaviour. Note: This keyword has non-standard behaviour within FME: if DISSOLVE_MODE is set to FME, then it is ignored. Otherwise, if it is not specified in the factory definition, then its default value is "yes". The ACCUM_INPUT_ATTRS clause specifies how attributes on input features are to be handled. If set to "no", no attributes from input polygons will be preserved, except those specified explicitly through the transformer parameters e.g. Group By, Attribute(s) to Sum, etc. If set to "yes", all attributes from input polygons would be merged onto the resulting dissolved polygon. When there are conflicts, one of the input polygons with the largest area will win. If unset, the factory will enter backwards compatibility mode, and accumulate attributes from input features only when one or more of the following parameters have been set: LIST_NAME, DISSOLVE_COUNT_ATTRIBUTE, AVERAGE_FIELDS, SUM_FIELDS, or WEIGHTED_AVERAGE_FIELDS. Note: This keyword has non-standard behaviour within FME: if ACCUM_INPUT_ATTRS is unset, it defaults to backwards compatible behaviour as described above. The SUM_FIELDS clause identifies attributes whose values are to be summed together when constituent polygons are dissolved and then assigned to the output polygons. The AVERAGE_FIELDS clause identifies attributes whose values are averaged during the dissolve operation. The WEIGHTED_AVERAGE_FIELDS clause identifies attributes whose values are averaged during the dissolve, weighted according to the area of the input polygon that they belonged to. The DISSOLVE_COUNT_ATTRIBUTE clause specifies the name of an attribute that stores the number of input polygons dissolved into an output polygon. The LIST_NAME clause specifies the name of a list into which the attributes of the input features are stored. Attributes from a feature with the largest area are stored at the head of the list, and no order is defined for the remaining elements. For example, if 3 input polygons are dissolved into 1 polygon, then that 1 polygon would have a list with 3 entries, each containing a set of attributes from one of the 3 input polygons. Output Tags The PolygonDissolveFactory supports the following output tags. POLYGON Dissolved Polygon features with attributes specified by GROUP_BY, SUM_FIELDS, AVERAGE_FIELDS, and WEIGHTED_AVERAGE_FIELDS clauses set appropriately. REJECTED Non-polygonal features that entered the factory exit the factory here untouched. INTERIOR_LINE If DISSOLVE_MODE is set to FME, this tag will produce line segments equivalent to the difference between the input polygons and the output polygons. TO BE RESOLVED MODE clause and NON_POLYGON output tag added to Syntax section above, but not documented.