Anyone who has attended an XMap GIS training program recently will likely have heard the instructor introduce the three critical steps necessary for the development of a GIS:
- Step 1 - Recognize the source or sources of the relevant datasets
- Step 2 – Process and manipulate the data so that it clearly conveys the appropriate information
- Step 3 - Establish a mechanism for sharing the results with colleagues, clients, constituents, or customers.
This article addresses an issue frequently encountered during step one of the development of a GIS: “How do I migrate my current data into a GIS format?
An organization that has decided to implement a GIS solution to manage information will likely have done so because other methods of data management are not providing the required level of functionality. It is fairly common in these situations for the data to already be structured in way that will allow it to be easily integrated into a GIS, assuming the necessary tools are available.
The first hurdle is figuring out how to assign the data to correct location on the map and what format this will take. Perhaps the simplest method for assigning geographic intelligence to a dataset is to utilize existing locational characteristics if they are available. Obviously, the presence of a set of coordinates for each record in the dataset will allow the direct import of the file into XMap through the GIS Layers Import function. Similarly, a list of addresses is sufficient to allow the creation of a GIS layer using the geo-coding functionality included in the Editor and Enterprise versions. In both of these cases, the result will be a set of points on the map representing the location of each record in the database.
But what if the existing data cannot, or should not, be represented by set of points but rather is best symbolized as series of polygons or areas? Such was the case with a medical research organization that recently participated in an XMap training program and needed to learn how to map their patient data to the appropriate ZIP Code. If the geo-coder had been employed, a point would have been created at the geographic center of the ZIP Code area, which would have limited the data display and analysis options. Instead the customer’s requirement was to represent the data as ZIP Code polygons, a process that required the importing and linking of the dataset to an existing GIS layer.
The first step in this process is to locate or create the geometric component of the layer. ZIP Code polygons (or more accurately, ZIP Code Tabulation Areas) are a reasonably common GIS dataset and are frequently made available for download through GIS data sites at the local and state level. For XMap users, DeLorme provides a free download of state-by-state ZCTA layers, preconfigured in XMap OpenSpace format. Many other preconfigured geometric files can be found through state or national GIS data portals. For a list of state-by-state GIS Web sites, click here.
If the areas to which the data is to be applied do not conform to preexisting geographical boundaries, it will be necessary to create a new GIS layer in XMap and to use the CAD tools to manually outline the required polygons. This is obviously a more time-consuming process.
When the geometric features of the layer are in place, the next step is to ensure that each record in the layer is uniquely identified and that this unique attribute matches a field or column in the dataset that will shortly be imported and linked to the layer. In the case of a preconfigured file, it is likely that such attributes will already be included in the imported layer. For instance, DeLorme’s ZCTA data includes two separate attribute fields containing the ZIP Code labels; one in numeric and one in text format. If, however, the geometry of the layer was manually drawn, it will be necessary to create a new field and to enter the unique identifier by typing the values in the attribute datasheet view.
The next step in this process is to import the file that contains the attribute data. This file can be in any of a number of formats including .xls, .dbf, .mdb, and .txt. The file is imported by clicking the Options button in the Attribute Design View in XMap, and selecting Import. It is important to note that this import function is not for creating a new GIS layer in XMap; instead, its purpose is to append attributes to a layer that is already in the workspace. A series of straightforward steps is followed to import the file and, when the import process is complete, a new window appears in which a link to the existing GIS layer is established.
Linking the new attributes with the appropriate record in the GIS layer involves simply selecting the name of the field from the current list of attributes in the left of the Link Attribute Sets window and then selecting the corresponding attribute in the imported dataset from the adjacent list.
Immediately, the combined results are displayed in the table at the bottom of the window, where there is also the option to see a list of any unmatched or duplicate records. When complete, click OK to append the new attributes to the existing GIS layer.
As a direct consequence of the fact that the imported attributes are linked using two identical columns, there will be duplicated values in the attribute table. While it is not possible to delete one of these columns without severing the link, the check box for either can be cleared in the Attribute Design View so that only one will be displayed in the datasheet view.
Now that the imported attribute set has been linked with the GIS layer and, as a consequence, the data has been assigned to the map, it is time to proceed to the second step in the development of a GIS by employing the classification, symbolization and querying tools.
This simple question was posed by a prospective 
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ll as road and backcountry navigation. Use the Waypoint tool to catalog, name, and symbolize key field locations for subsequent downloading and integration into an XMap GIS layer. Create waypoints based on GPS location, selected map location, or by entering known coordinate values. Record track files to monitor movement and trip details or to map linear features such as a new roads, trails, or property boundaries.