Autodesk 15606-011408-9330 User Guide - Page 179

datum Information about the interpretation of the Earth on which the coordinate system is based. The datum can include the size and shape of the Earth (such as an ellipsoid or flat map), origin point, orientation, and more. The datum is critical for accuracy, because if a different datum is applied to a coordinate system, the coordinates will fall onto different positions on the Earth. decimal degrees The mathematical representation of degrees in floating point values. For example, in decimal degrees, 30°30'0" is 30.5°. degrees° minutes' seconds" The mathematical representation of degrees as minutes and seconds, where one degree equals 60 minutes and one minute equals 60 seconds. For example, in degrees° minutes' seconds", 30.5° is 30°30'0". DGN file format See Microstation Design File. digitize To convert spatially dispersed information on maps, drawings, or charts into machine-readable digital data that can be processed by computer software. Digitizing captures spatial data as XY coordinates in digital form. display range The maximum and minimum scale at which Autodesk MapGuide will display a layer. In Autodesk MapGuide Author, you can specify that a layer will display only at certain ranges, or specify multiple display ranges for a layer and specify different attribute styles for each of the display ranges, so that the layer will be drawn differently depending on the current scale at which the map is displayed. By default, Autodesk MapGuide displays the layer regardless of the current scale. See also map scale. display styles A set of properties that define how to display data on the layer. Layers without themes typically have only one display style, which defines how to display all of the data on the layer. Layers with themes typically have multiple display styles: one for each category in the theme. You specify different properties for each display style, such as color, fill style, line width, or point symbol. Display styles are defined for each style set on a layer. drive alias A name for the location of drawings attached to an Autodesk Map project drawing that replaces the traditional file path. Drive alias information is stored in the Autodesk Map initialization file (acadmap.ini). Network users of Autodesk Map typically assign the same drive alias to a network location when they share projects containing attached source drawings. You create the aliases in Autodesk Map or by editing the acadmap.ini file. The acadmap.ini file is shared by all your Autodesk Map projects. dynamic layer A layer that gets data from Autodesk MapGuide Server as the user zooms in and out on the map, turns the layer on and off, and so forth. Unlike static layers, which store all of the data for the entire layer in the MWF, dynamic layers download only the data needed for the current view, so the dynamic option is better for layers with large data sets or data that needs to be kept more secure. ECW See Enhanced Compression Wavelet. ellipsoid An approximation of the Earth's shape that does not account for variations caused by non-uniform density of the Earth. Enhanced Compression Wavelet (ECW) Supported by ER Mapper, a wavelet-based image compression format with high-quality results at high compression rates. extents The smallest rectangle that contains all features in a map, that is, the outermost boundaries of the map. extranet An intranet that is available to authorized users outside of the organization. Glossary | 179