Planimetric accuracy of Ikonos 1m panchromatic orthoimage products and their utility for local government GIS basemap applications

A detailed assessment of the planimetric accuracy of high-resolution panchromatic Ikonos orthoimage products for three different test sites is presented. The main objective was to evaluate the potential of Ikonos orthoimage products for use as digital image basemaps in local government Geographic Information Systems (GIS) systems. For maximum utility and adoption, a planimetric accuracy of 3-5 m and a circular error at 90% probability (CE90) is considered nominal for local government planning and management applications. Low-precision, low-cost georeferenced Ikonos image products (Geo, 50 m CE90) were orthorectified using third party commercially available software and various custom Digital Elevation Models (DEMs). The planimetric accuracies of the resulting custom Ikonos orthoimages were found to vary between 2-4m CE90. In addition, United States Geological Survey (USGS) DEMs were also used to orthorectify georeferenced Ikonos image products. Planimetric accuracies of 2-3 m CE90 were obtained from georeferenced Ikonos using USGS DEMs with RMS vertical accuracies of the order of 2 m. The approach demonstrated here can be used to deliver up-to-date, cost-effective orthoimages from Ikonos Geo products that yield planimetric accuracies suitable for use as digital image basemaps by local governments.