Function Description

Merges objects that meet certain conditions in a line dataset, region dataset, or text dataset into a single object. This function is applicable to line datasets, 2D region datasets, 3D line datasets, and text datasets. For text datasets, the default processing method is Group only.

The following conditions must be met for dataset dissolve:

• The values of a certain field between data objects are the same.
• Line objects must have coincident endpoints to be dissolved.
• Region objects must intersect or be adjacent (sharing a common edge).

The dataset dissolve function includes three processing methods: Dissolve, Group, and Group after Dissolving.

• Dissolve:

  Dissolve objects numbered 1

  As shown in the results, dissolve merges multiple sub-objects into a single simple object. Regions numbered 1 are dissolved, but non-adjacent objects are not dissolved.

• Group:

  Group objects numbered 1 into a compound

  As shown in the results, group combines multiple sub-objects into a compound, where the overlapping parts of the objects are processed using the XOR operation.

• Group after Dissolving:

  Group objects numbered 1 into a compound

  Objects with the same property field value that intersect or are tangent are first dissolved into a single simple object. If after dissolution, there are non-adjacent objects with the same merged field value, they are further grouped into a complex object.

Function Entry

• Data tab -> Data Processing group -> Vector -> Dissolve.
• Toolbox -> Data Processing -> Vector -> Dissolve.

Parameter description

• Source Dataset: Displays all line and region datasets under the selected data source. Select the dataset to be dissolved.
• Dissolve Mode: The system provides three dissolve modes.
  • Dissolve: Merges objects with the same property field value that intersect or are within the dissolve tolerance range into a single object.
  • Group: Groups objects with the same property field value into one object, and the overlapping parts are removed.
  • Group after Dissolving: First dissolves objects with the same property field value that intersect or are tangent into a single simple object. If after dissolution, there are non-adjacent objects with the same merged field value, they are further grouped into a complex object.
• Dissolve Tolerance: If the distance between two or more nodes is within this tolerance range after dissolution, they are merged into one node. The default value is one millionth of the dataset's boundary range (the maximum tolerance is 100 times the default tolerance), and the unit is the original unit of the dataset.
  Note:

  For text dataset dissolution, only the Group method is supported, and the dissolve tolerance cannot be set (meaningless).

• Filter Expression: Only objects that satisfy this condition participate in the dissolution operation.
• Process objects which have no field values: If this checkbox is selected, objects with empty merged field values participate in the dissolution operation.
• Merged Field: A field in the dataset that has the same field value. Data dissolution and grouping are performed based on the values of this field.
• Statistic Field: Performs field statistics on dissolved objects (generating new fields to store statistical values). The statistics type can be Max, Min, Sum, Average, First Object, Last Object, Text Link.
  • Max: Finds the maximum value of the field for dissolved/grouped objects, valid only for numeric and time fields.
  • Min: Finds the minimum value of the field for dissolved/grouped objects, valid only for numeric and time fields.
  • Sum: Calculates the sum of the field for dissolved/grouped objects, valid only for numeric fields.
  • Average: Calculates the average value of the field for dissolved/grouped objects, valid only for numeric fields.
  • First Object: Obtains the field value of the object with the smallest SmID in the dissolved/grouped objects.
  • Last Object: Obtains the field value of the object with the largest SmID in the dissolved/grouped objects.
  • Text Link: Obtains a string of field values concatenated with semicolons (;) for dissolved/grouped objects, valid only for text fields. Application scenario: In a highway dataset containing an administrative division field, during dissolution, the values of this field are concatenated with semicolons to indicate which administrative regions the highway passes through.
    Note:

    When using this type, the merged field must be set, and the merged field values of text link objects must be the same.

• Preserve the table structure of the source dataset: Check to preserve the table structure of the source dataset. When this parameter is checked, the table structure of the source dataset is preserved, meaning all other fields not selected as merged field or statistic field are retained, and the field values are empty.
• Result Data: Name and save the dissolved result dataset, and select the data source for the dataset.

Related Topics

Ungroup

Merge Datasets

Integrate

Aggregate Polygons