Planimetrics open new levels of geospatial analysis

A new regional data set based on regional aerial photography is opening new levels of map-based analysis at the Cape Cod Commission and Cape towns.

Planimetric data are digital points, lines and polygons representing features on the ground – such as manholes, coastal infrastructure and catch basins – that can be used in geographic information system mapping applications. The data for this project derived from three-dimensional interpretation of the 2014 regional flyover, which collected new, regionally-consistent aerial images of the entire Cape.

In its most basic form planimetrics creates a more realistic base map to add the context of an aerial photo with the power of vector data. With planimetrics data, aerial images become more than just pictures. Details such as sidewalks, striped parking spaces and telephone poles can be quantified, summarized and analyzed. A subcommittee of Commission and municipal GIS staff selected 156 planimetric features with both regional and local importance.

Most planimetrics projects are completed at a project or municipal scale. At a regional level there are many interpretations of how a feature should be collected, which structures are essential, and what attributes can be applied. Additional processing of the data added local-level details not attainable from the imagery, such as hydrant numbers.

The Commission will be putting this data to use in its coastal resiliency work, Greater Hyannis project, regional capital planning including wastewater and stormwater, and Regional Policy Plan update.

The planimetrics and regional flyover projects  were developed through the the Commission’s Strategic Information Office (SIO) and its governance committee. All of the Cape Cod towns participated in  the single flyover, which saved the region an estimated $800,000 versus the traditional practice of individual flights.

After a final round of data review, the  Commission will provide this data through its publicly-available online data portal.