GISP Study Guide All Answers Correct

GISP Study Guide All Answers Correct Geodatabase Definition: An object-oriented spatial model representing the native data structure for ArcGIS. It serves as the primary format for storing, editing, and managing geographic data. Types of Geodatabases Personal Geodatabase File Geodatabase Enterprise Geodatabase Workgroup Geodatabase Types of Geodatabase Datasets Geometric Network Network Dataset Parcel Fabric Terrain Dataset LAS Dataset Distance Relations Definition: Specifies the distance between an object and a reference object. Examples of Distance Relations At Nearby In the Vicinity Far Away Distance Calculations Euclidean Distance: The straight-line distance between two coordinates, calculated using the formula: [ sqrt{(x_1 - x_2)^2 + (y_1 - y_2)^2} ] Manhattan Distance: The sum of the vertical and horizontal distances, calculated as: [ |x_1 - x_2| + |y_1 - y_2| ] Directional Relations Internal Direction: Refers to the location of an object that is situated inside the reference object. External Direction: Refers to where an object is located outside the reference object. Spatial Models Definition: Describe the basic properties and processes for a set of spatial features. Data Types Vector Data: Comprised of points, lines, and polygons representing discrete features. Raster Data: Consists of rectangular arrays of regularly spaced square grid cells, with each cell containing a value or attribute. Pixels and Cells Pixel: The smallest resolvable unit of a scanned image; every pixel is a cell in raster data, but not all cells are pixels. Temporal Data in GIS Definition: Recognizes that the world is continually changing; static maps can only represent one temporal state at a time. Imprecision and Uncertainty Imprecision: Arises because data is transformed from a 3D globe to a 2D surface through spatial transformations (like projections and datums), resulting in data distortions. Uncertainty: Indicates that GIS data, created or collected at a specific time, may be outdated. Geoid and Mathematical Models Geoid: The theoretical shape of Earth defined by mean sea level and influenced by topographic and gravitational factors; represents what Earth would look like without continents. Reference Ellipsoid: A mathematically defined surface that approximates the geoid, serving as a more accurate representation of Earth's shape. Oblate Ellipsoid: An ellipsoid where the shape is derived from rotating an ellipse about its minor axis, fitting the geoid as a first-order approximation. Sphere Definition: Refers to the idealized shape of Earth; while the semi-major axis 'a' and the semi-minor axis 'b' differ by just over 21 kilometers, Earth is not perfectly spherical. Spatial Reference Systems Spatial Reference System (SRS) or Coordinate System (CRS): A coordinate-based system—local, regional, or global—for locating geographical entities. International Terrestrial Reference System (ITRS): A three-dimensional coordinate system with a defined origin (the Earth's center of mass) and three orthogonal axes (X, Y, Z). Map Projections Definition: The process of transforming coordinates from the curved surface of Earth to a flat map representation. Horizontal Datum Definition: A model that represents Earth as a spheroid, consisting of two components: a reference ellipsoid and a set of survey points defining the spheroid's shape and its position relative to Earth. Vertical Datum ️reference point for elevations of surfaces and features on the Earth-could be based on tidal, sea levels, gravimetric, based on a geoid What kinds of things can be distorted with different map projections? ️Distance, direction, shape, area Datum ️Model of the earth as a spheroid