GEOG 379 Lecture Notes - Lecture 5: Arcgis, Unique Key, Centimorgan
Document Summary
2/14 vector data model & geometric representation. Data in gis: all gis data types contain 2 distinct elements, spatial data a(cid:374)s(cid:449)e(cid:396)s (cid:862)(cid:449)he(cid:396)e(cid:863) (cid:395)uestio(cid:374)s, attribute data answers all other questions. Vector data formats: 3 most popular formats: Relatively small, and still the most widely used format. Allows for multiple data sets in a single file and more sophisticated treatment of topology. Each data set consists of an entire file directory. Multiple files in each data set make copy and transport somewhat difficult (especially if done outside of. Arccatalog: tin (triangular irregular network, topological data model for surfaces (ex elevation) made up of connected triangles (faces, triangle nodes have x, y, z values, triangles may be sized differently, based on original data density. Indicates relationship in size b/w objects + distances on map to those in real world: can be expressed as the ratio of two numbers, distance on map distance in real world.