mter program processing transforming the positions into the ground late system. The direct link between the stereocompiler and the iminates the usual intermediate manuscript preparation stage and zing from the manuscript. This methodology yields a reduction in on and results in ultimately higher accuracies on the digital map y Regional Planning Commission, 1980). Elevation data can be is contour lines, profiles with elevations recorded at regular intervals rain slope, or as geomorphic points along drainage lines or hillcrests, ic photogrammetric instruments are equipped with automatic image reduce a high density of elevation data points, 'map information is stored in its own "layer," in conjunction with its, in the manner depicted in Figure 3.1. This allows for retrieval Dmbination of levels, such as roads and contours or buildings and he layering also provides the greater flexibility in producing maps update process.
1 that the cadastral parcel layer of a digital map system contain ;ical references. That is, each property-line segment in the cadastral e its own unique identifier and a record that includes the identifiers as well as the parcels that it bounds. Each end point of property-50 must have a unique identifier and a record identifying the line j parcels that meet there. Attached to these point and line records nformation on their locations, the date and accuracy of the location nd how the points can be relocated in the field. Only with such *ical and survey data can a digital cadastral overlay be a "living dily updated as conditions change and that submits readily to au-its completeness and consistency. The same is true for any other to be a complete and up-to-date public record, e.g., of a utility
iteractive graphics task is usually data editing. While data editing producing a graphic plot on a digitally controlled plotting table, the ; would be to display the data on a digitally controlled cathode-ray ; operator can then determine overlapping, erroneous, or missing nake the corrections on the CRT or request a redigitization of the ^reo model.
lata are rarely in form for immediate use, and extensive computer typically required to arrange the data in an appropriate format. This iy include coordinate transformation from stereomodel coordinates erence system such as Universal Transverse Mercator Coordinates loordinates. Most data-acquisition schemes acquire far more data •equired in the final data files. Therefore, techniques of data compres-iployed to reduce the amount of data to a manageable quantity, nent of the preprocessing system is format conversion, to convertamong a broad variety of surface features. This information can be put to ictical use in such applications as agricultural crop forecasting, rangeland and forest .nagement, mineral and petroleum exploration, land-use management, water-qual-evaluation, and disaster assessment. Map information from these applications can imately be merged with the cadastral base map and overlay to relate the information the land parcel. Use of Landsat imagery is important because of the large volume frames available and the continuance of the project with Landsat D. While future $ 0.27