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Saturday, 5 December 2015

Mathematical operations in OpenWebGIS (on the attributes of map layers)

In the description of geographic information system OpenWebGIS there is often a phrase:
"In OpenWebGIS you can use the extensive mathematical functionality to calculate and analyze your data." 
It is written because OpenWebGIS has a large set of such functions, among them there are geomathematics functions and mathematical operations on the attributes of map layers. OpenWebGIS (only in the online version) has a large set of geomathematics functions (functions as WPS, provided by Geoserver, and work with them is automated by OpenWebGIS). This function is available through menu item "Calculation->Geomathematics". See Figure 1.

Figure 1- List of geomathematics functions in OpenWebGIS
About each of these functions it is possible to write a separate article, starting with the scientific description of its algorithm and finishing by the method with the help of which the result is added to the map. But in this article we will dwell on the description of mathematical operations on the attributes of map layers. To make mathematical operations on the attributes of the layer, you need to select the name of the layer in the list of "Editable Layer", and then the menu item "Edit-> Open attribute table". Then a window will open for working with attribute information and attribute table. This window is shown in Figure 2.

Figure 2 - Attribute table of the Layer