What do you do if the information you need is not available digitally? Communities may wish to include more specific information about local resources that is not available in GIS format, or may require new data collection, such as scenic areas and recreational resources. In addition, certain datasets in GRANIT do not include statewide coverage. Several options are available to make information compatible with GIS maps:
Digitizing new data: Information about natural resources can be digitally traced (digitized) to create a new GIS data layer for the study area. Digitizing is labor intensive and can be costly. However it can be well worth the effort to get the information into GIS. Once in the system, data can be easily accessed and modified for future updates. Note that digitizing produces data that is only as accurate as the source data. Professional assistance is needed to digitize data.
Using a Global Positioning System (GPS) instrument: GPS instruments can be used to record new natural resource information. This is a lower cost option than digitizing, and has a higher level of accuracy, but it requires intensive field work and some experience. Many land surveyors have GPS capability and experience. UNH Cooperative Extension conducts workshops in the use of GPS and loans out mapping-quality units for community projects.
Creating manual overlays: This is the least expensive option for including information not currently in GIS. It can also be used to temporarily update existing GIS data. For example, if you decide to update your town’s NRI maps periodically, the manual overlay method could be used to keep the maps current during the intervening years. To include data manually, there are two options:
- Print an outline of the municipal boundary or study area on architectural tracing paper or mylar. These transparent materials can be overlaid with the NRI maps, and new or updated natural resource information can be manually drawn on them.
- New or updated information can be added directly to paper copies of the existing maps. Ensure that the information is entered as accurately as possible. These data can subsequently be digitized.