| Abstract | Databases supporting the integration of various layers such as soils, land use, land cover, and farm limits are fundamental to GIS application projects. Building such databases from a variety of sources
requires a common reference base map. This presentation is based on an experience in Ukraine, where up-to-date base maps at the scale of 1:25 000 - 1:100 000 are needed to support decision-making dealing with the consequences of the Chornobyl
disaster. Creation of a topographic base map for Chornobyl is part of the Institution Capacity Building for Remediation Activities project supported by a CIDA contribution. As it is difficult to obtain maps and data in Ukraine, use of satellite
images was investigated. SPOT and IRS-C images were chosen and two geometric correction methods were evaluated: polynomial modeling and orthorectification using a mean elevation datum. Ground control points were extracted from 1:200 000 maps.
Orthorectification provided an adequate background over flat areas, while requiring fewer ground control points and human resources than the polynomial modeling. However, in mountainous areas such as the Carpathian region, a digital elevation model
is strongly recommended. Cartographic features were then extracted from SPOT and IRS images to produce the base maps. Results show that panchromatic images are suitable as a stand-alone product to create a geographic database and provide basic
land cover information. The paper provides an overview of the Ukrainian organizational context, focuses on the description of the geometric correction methods within a situation of limited data availability and illustrates the project results.
Keywords: satellite imagery, topographic base, data integration, international projects |