Data Input

With municipal utility lines, data input into GIS usually involves an initial input of all available data that often exist in various forms (paper archive of surveying maps, tachymetric archives, AutoCAD drawings in various formats, design engineering drawings and similar). When inputting data, all available information is used with the goal of creating a unique and the most accurate possible database which can be further updated in a single location and which will always be available to all users in its most up-to-date version. Input has both a graphic and an attribute aspect.

For parts of the network that are located in several data sources, the basic principle when inputting data is to draw from the most accurate and reliable source, whether we are talking about coordinates, heights, or other attribute descriptions. In the absence of quality sources, data is entered from less accurate sources in order to complete the description, but it is accompanied by the source's records and an assessment of the reliability of each piece of data (metadata).

In addition to utility lines, all related facilities for which data are available are entered into the spatial database when information is available from background maps or raster images. Coordinates and attribute accuracy are not lost in the input process. During data input, all topological and attribute checks are performed, and for locations where information is unclear or not completely defined, and which cannot be clarified during input, a “trace” is left in the form of a spatial layer of deficiencies that the user will subsequently correct (field work, surveying, etc.)

In recent times, it has become increasingly common for the initial data input to involve conversion of data that is in CAD or GIS format, received from another contractor. In each actual case, an assessment must be made as to what degree such a conversion can be made automatically with a program routine, and to what degree it will be necessary to vectorize vectors and to transcribe attributes. Even with such automatic transfers, topological and attribute checks are of course performed, and the data are organized and supplemented to the greatest extent possible.

If at all possible, the initial data input should be accompanied by a link with the business information system from which the spatial arrangement of the user of the utility in question is obtained. In this way, it is easier to obtain information about the parts of the system for which records do not exist.

An integral part of the data input work consists of editing all of the raster and vector maps that the user has available and organizing and including them in the GIS so that use of the maps can be reduced to automatic plotting, taking into account the scale and area in which we are located.

It is common that after the input of existing data into the GIS, an analysis of the quality and coverage of data is done, and that consequently, a study is made of deficiencies in the GIS data with which an investor can plan further efforts toward improving the quality and coordinate accuracy of data.