Function Description
Merge a Polygon with a smaller area onto a polygon with a larger area.
In the process of data production and processing, it is likely to produce some small polygons, which are called broken polygons. You can use the Eliminate Small Polygons function to Eliminate Small Polygons these thin polygons into adjacent large polygons, or to delete isolated polygons (isolated polygons are not adjacent to or tangent to other polygons and are not easy to merge). In order to simplify the data.
Generally speaking, polygons with an area much smaller than that of other face objects in the Dataset can be considered as "broken polygons", which is usually between one millionth and one ten thousandth of the area of the polygon with the largest area in the same Dataset. However, in actual operation, the appropriate Minimum Polygon can be set according to actual needs. Node Snap Tolerance is used to determine whether polygons are adjacent. It is not reasonable to set too large a tolerance on the Objects of faces that are apart, or on polygons that are actually adjacent, either of which can lead to Failed to merge tiny polygons.
As shown in the figure below, it is the result of Eliminate Small Polygons processing of surface data. Fig. 2 is the effect of Eliminate Small Polygons into adjacent large polygons.
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| Figure 1: Before Eliminate Small Polygons. | Figure 2: After Eliminate Small Polygons. |
For isolated polygons with an area smaller than specified Minimum Polygon, the effect of selecting Delete Single Region is shown in Figure 3:
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| Figure 3: Delete Single Region |
Function entrance
- Data tab-> Data Processing-> Vector-> Eliminate Small Polygons.
- Toolbox, Data Processing, Vector, Eliminate Small Polygons.
Parameter Description
In the Eliminate Small Polygons dialog, a Dataset to be processed by Eliminate Small Polygons is added through the toolbar, and United Value Settings is possible. Set Parameters in the list box, including Node Snap Tolerance, Min Polygon Area, and deleting isolated small polygons.
- Delete Single Region: Select this check box in a Dataset so that if isolated polygons (not intersected or tangent to other polygons) are encountered, they will be automatically deleted.
- Node Snap Tolerance: If the distance between two nodes is less than tolerance value, the system will automatically merge the two nodes into one node during the merging process. The default tolerance values are related to the Dataset's coordinate system and are described in the tolerance description .
- Min Polygon Area: Polygons smaller than this area value are combined as broken polygons. The system will automatically set the value of the Min Polygon Area field to one millionth of the maximum object area of the Dataset according to the added Dataset. The user can reset the value of the field. It is recommended to input the value of the field from one millionth to one ten thousandth of the maximum object area of the Dataset. However, you can enter a value outside this recommended range and polygons smaller than this area will be merged.
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