Impervious Surface Maps: Chasing Imagery

Provided by guest blogger, Daniel Ngoroi, Woolpert subject matter expert, Dayton

Accurate impervious surface maps have always been an essential foundation for stormwater management, flood and erosion control, watershed protection and water quality protection. For most agencies and jurisdiction around the country, the update cycle for impervious maps lags woefully behind the update cycle of aerial imagery and LiDAR.

Users of these maps require timely data representing the extent of impervious cover and the data has to match the imagery available. Woolpert has developed a feature extraction technique that relies on automated data analysis for identifying various ground phenomena including impervious surfaces. The backbone of this automated technique is the effective fusion of electro-optical data and elevation data from LiDAR sources to recreate the landscape, thus enabling intelligent identification of land cover types.

The process of feature identification semantically eliminates land cover types that do not represent imperviousness. Should manual editing be required, the intelligent datasets produced from this process reduce the amount of time required to perform the edit tasks. Using this method, Woolpert creates accurate impervious surface maps and is able to deliver the data faster than traditional mapping could through softcopy technology thereby keeping the relevant GIS layers up to date and in sync with robust acquisition cycle of the base imagery.

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