Urban Mapping


GRAS offers a highly automated impervious surface area solution which is designed to provide practitioners and decision makers with the ideal reference information needed for hydrological modelling and urban planning. By reducing the dependency on visual interpretation the method is cost-effective and consistent.

This product is an ideal solution for urban storm water management and storm water tax calculation. The mapping can be performed based on existing ortho-photographs to save on the total cost, or based on very high resolution satellite images. The data is ready for use in hydrolgical modelleing software or GIS and the high degree of automation ensures consistent data and fast delivery.


Methodology
Aerial photographs and satellite images are important sources of information for imperious surface mapping. Both provide an overview of the survey area at a specific point in time, and can be used to differentiate various types of impervious surface areas (roads, rooftops, parking lots etc.) from the pervious areas.

For Impervious Surface Mapping, GRAS is using state-of-the-art object-based image analysis since this approach allows for the detection of landscape objects – objects that can often be directly linked to topographical units such as segments of buildings and roads.The ability to incorporate GIS themes such as road layers, building database information etc. directly into the segmentation and classification routines is a further advantage of the object-oriented approach which helps to improve the accuracy of the impervious area map. Depending on the requirements of the analysis it is also possible to map different surface types that may have different environmental profiles. For instance, certain roof types such as copper will have a larger impact on water quality and the need for treatmemt.

Price and conditions
The price of Impervious Surface Mapping varies and relates to factors such as size of the area, input data types and availability of ancillary data etc. Mapping can be done based on existing aerial photographs or based on satellite images in Very High Resolution with a spatial resolution of 0.5 – 1 m. For overall river basin mapping it is also possible to perform the mapping at smaller scales using medium resolution satellite images.

Please contact GRAS for further information about the possibilities for Impervious Surface Mapping.