![]() Using this data, each county has a value of either 1 or 0 (blue or red), and this is the criteria by which they are symbolized in the map examples, and also by which the dissolve is run. In this example, the original attribute table contains several columns of data, one of which is 'Blue'. It is the removing of boundaries between adjacent polygons having the same value for a specific attribute, combining polygons that would otherwise be assigned the same color or hatch pattern in a thematic map display. Dissolving Attribute DataĪs the dissolve process does not retain all of the underlying attribute data of the original undissolved features in the new dissolve layer, it is important to understand how the dissolve operation affects data and how to achieve desired results. It should be noted that Merge is different than the Aggregate feature because no change in dimensionality (i.e. Some authors have used the term merge to refer to the combination of lines and the term amalgamation to refer to the combination of polygons, although this operation can be performed on points as well. "The merge operator combines an array of related features into a single representative feature without a change in dimension” and has also been referred to as amalgamation, dissolving, agglomeration, dissolution, and fusion. Main article: Cartographic generalization ![]() The dissolve operation is useful for performing these and many other tasks which a cartographer or GIS user may encounter. Other uses include combining separate counties in a state to emphasize a common variable, or combining multiple countries into their respective continents. For example, a cartographer or GIS user may desire to show several distinct polygon areas as one contiguous area, such as combining certain areas into one large region (for instance, merging east and west Germany into Germany). This can create problems for analysis or display, but dissolve can be used to combine them together and facilitate their intended use. For example, road or river datasets often present the same linear feature in a number of segments. ![]() ĭissolve has various applications in cartography and GIS. Giving linear features a dotted appearance or connecting linked line segments into one larger line segment in a GIS is also considered a dissolve operation. Thus, using the dissolve operator on multiple polygons with a common value will yield one new polygon, combining the dimensions of the original, dissolved polygons. In choropleth maps, the dissolve operation eliminates the boundaries of enumeration units with a common value, depicting a much larger area holding the same common value. In GIS, dissolve is one of the Data Management tools used for generalizing features. This means it is very easy to identify which polygons are not covered by A2 by null attributes that have been acquired from A2.Dissolve is an application of the conceptual operators that aggregates features often referred to as 'Merge' or 'Amalgamation.' It is a process in which a new map feature is created by merging adjacent polygons, lines, or regions that have a common value for a specified attribute. ![]() OR select by attributes as Union will append attributes from A1 and A2 to A3.
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