Traditional methods for GIS basemapping data acquisition are about to change. In 1997, one meter resolution satellite imagery of the earth's surface will become available to commercial customers on a regularly scheduled or customer-specific basis. Beneficial aspects of satellite-derived imagery include rich, multispectral information content, high accuracy, timeliness, frequent revisits, digital feature extraction, automated change detection, digital correction and rectification, and terrain modeling. New methods for imagery capture will allow for customer tasking of satellites to obtain specific areas of interest within a matter of hours. In addition, when satellites are not specifically tasked, they may capture imagery that will be archived and made available to customers shortly after receipt of order. Such archives will also allow customers to order temporal sequences of respective data. Many GIS applications require high-accuracy imagery that meets national map standards of 1:24,000 without ground control. With ground control, image accuracy should be as high as 1:2,400. These applications may also require color imagery with resolution as high as 1 meter. Beginning in 1997, all of this will be accomplished at a fraction of the cost of traditional aerial mapping.
Working with image data can often be frustrating and time consuming. Mismatched coordinate projections and unbalanced color tables are a few problems GIS users encounter. However, accurate digital imagery can yield a wealth of new information to vector datasets and even improve their positional accuracy. Custom aerial projects may be too costly for projects covering large areas. This paper will discuss the use of a new emerging class of ready-made image data products provided by aerial firms and soon satellite providers. At high resolutions, this ortho-rectified imagery offers "off the shelf" geo-referenced, tonally balanced data at a lower cost than custom aerial project. When to use this new one meter resolution image or fly a custom aerial flight will be discussed. Case studies in the San Francisco Bay Area will be presented.
PROJECT BACKGROUND This project was initiated and it is paid for by the investors to fulfill their needs in establishing a GIS which will enable them to assess the influence of the proposed Novo Virje power plant location on the environment. DESCRIPTION Existing maps 1:25000 (last time updated 25 years ago) were rectified, digitized and structured into a GIS database. Responding to the investor's request content was somewhat reduced (lonely trees, houses were left out, etc.). Updating of the map content was done using remotely sensed data from the Russian KVR-1000 satellite (panchromatic, 2 meters spatial resolution) using on-the-screen digitizing technique. CONCLUSION This methodology has been chosen because it is the most rational way (less administrative hassle, cheaper) to update 1:25000 maps. SOFTWARE USED ArcInfo 7.0.3. CPS 2.0 (Cartographic Production System) ERDAS IMAGINE 8.2.