Dissolve

Function Description

Merges objects meeting specific conditions in line datasets, region datasets, or text datasets into single objects. This function applies to line datasets, 2D region datasets, 3D line datasets, and text datasets. For text datasets, only Group processing mode is supported by default.

Dataset dissolving must meet the following conditions:

  • Objects share identical values in specified field(s)
  • Line objects require coincident endpoints for merging
  • Region objects must be adjacent or intersecting (sharing common edges)

The dissolve function provides three processing modes: Dissolve, Group, and Group after Dissolving.

  • Dissolve：
    Dissolve objects with ID 1

    As shown above, the Dissolve mode merges multiple sub-objects into a single simple object. Regions with ID 1 are merged, while non-adjacent objects remain separate.

  • Group：
    Group objects with ID 1 into a compound

    The Group mode combines multiple sub-objects into a compound object, where overlapping areas are processed using XOR operations.

  • Group after Dissolving：
    Group objects with ID 1 into a compound

    First merges objects with identical property field values that are adjacent or tangent into simple objects. If non-adjacent objects with identical merged field values remain post-merging, they are further grouped into complex objects.

Feature Entry

  • Data Tab->Data Processing Group->Vector->Dissolve
  • Toolbox->Data Processing->Vector->Dissolve

Parameter Description

  • Source Dataset：Displays all line/region datasets in the selected datasource. Select the dataset to dissolve.
  • Dissolve Mode：Three modes available:
    • Dissolve：Merges objects with identical property field values that intersect or are within tolerance range.
    • Group：Groups objects with identical property field values, removing overlapping sections.
    • Group after Dissolving：First dissolves adjacent/tangent objects with identical property fields, then groups remaining non-adjacent objects with identical merged fields.
  • Tolerance：Nodes within this distance will merge post-dissolve. Default: 1/1,000,000 of dataset extent (max 100x default). Unit: Original dataset units.
    Note:

    Text dataset merging only supports Group mode, and tolerance is disabled (irrelevant).

  • Filter Expression: Only objects meeting this condition participate in merging.
  • Process objects which have no field values：When checked, objects with empty merged field values are included.
  • Merged Field: Field whose identical values determine merging/grouping.
  • Statistic Field: Performs field statistics on merged objects (new fields store values). Statistics types: Max, Min, Sum, Average, First Object, Last Object, Text Link.
    • Max: Maximum field value in merged/grouped objects (numeric/date fields only).
    • Min: Minimum field value (numeric/date fields only).
    • Sum: Sum of field values (numeric fields only).
    • Average: Average field value (numeric fields only).
    • First Object: Field value from object with smallest SmID.
    • Last Object: Field value from object with largest SmID.
    • Text Link: Semicolon-concatenated text field values (text fields only). Use case: Highway dataset with administrative division fields shows all passed regions when merged.
      Note:

      Requires merged field specification. Text link objects must share identical merged field values.

  • Preserve the table structure of the source dataset：Retains source dataset's table structure. Unselected fields (non-merged/statistic) are preserved with empty values.
  • Result Data：Name and save dissolved dataset, selecting target datasource.
Note:

Three or more lines sharing endpoints with identical merged fields will not dissolve.

Related Topics

Ungroup

Merge Datasets

Integrate

Aggregate Polygons

Divide Region