# GIS

Flashcards by Weltraumkatze Fanroth, updated more than 1 year ago
 Created by Weltraumkatze Fanroth over 5 years ago
133
7

### Description

Klausurvorbereitung

## Resource summary

 Question Answer Was zeichnet spatial reference aus ? - The coordinate system (GCS or PCS & VCS) -The spatial extent covered by the dataset (Ausdehnung) - Coordinate prescision with coordinate are stored (Koordinatengenauigkeit) -Processing tolerances (Bearbeitungstoleranz) Was enthält das Vertikal-Koordinatensystem (VCS) (Vertical coordinate system) - Linear unit of measure (i.d.R. m or ft) - Geodectic or vertical Datum - Axis direction -Vertical shift (verschiebung) Was umfasst das Projizierte Koordinatensystem (PCS) ? - GCS - Projection ( and project. parameters) - Linear unit measure ( usually m or ft) Was beinhaltet ein Geographisches Koordinatensystem ( GCS)? - Angular unit of measur (usually degrees) - Prime median - Datum (including spheroid) Was geben Koordinatensysteme an? Coordinate system specify - A Projected or Geographic measurment framework - Units of measurment - A defined map projection - Datums and spheriod, plus possible shift, central meridians and standard parallels. Was ist der Tisso Index ? A method of investigating how map projections can distort the Earths surface going from a 3D to a 2D projection. What means " Great circle" ? = shortest distance between two points an a sphere ( called a Geodesic in Mathematics) Wie lautet das Datum vom Mittelpunkt der Erde? Ellipsoid - GRS 80 Datum - NAD 83 Was versteht man unter "Datum" ? Datums are collections of poinst of "known" accuracy that are used to georefernce map data Wie liegen die semi-minor axis & semi-major axis ? semi-minor I I ----------- semi-major Sphere Geoid Ellipsoid What is Remote Sensing? "The science and art of obtaining useful information about an object, area or phenomenon through the analysis of data acquired by a device that is not in contact with the object, area or phenomenon under investigation" Was ist GIS? "GISs are simultaneously the telescope, the microscope, the computer and the Xerox machine of regional analysis and synthesis of spatial data" Nennen sie 4 Eigenschaften von Projectionen 1. Angular conformity, or preservation of shapes ( conformal proj.) 2. Preservaton of distance ( equivalent proj.) 3. Preservation of area ( equivalent proj.) 4. Preservation of direction (azimuthal proj.) Was ist Lidar? -Lidar ist a laser based active remote sensing technique that can operate from space based, airbone or ground based plattforms and provide very accurate 3D data. - It requires an emmitter-reciver, plus accurate GPS and IMU information - It can rapidly provide, bare earth high resolution DEM. - Uses include geomorphological mapping and fault identifikaton and analysis Slope and Aspect The rate of change of elevation in both the x and y direction can be used to identify the direction and magnitude of steppest gardient Was ist das? TIN vector data structure DEM vector data structure What means TINs Triangulated Irregular Networks " A vector data structure that partitions geographic space into contiguous, non-overlappig triangles. The vertices of each triangle are sample data points with x-,y-,z- values." Pro Vector - Data can be represented in its original resolution -requires les storage space - Topological relationships maintained - Geographical output visually pleasing Contra Vector - More complex data structure - inefficient for RS data - Some spatial analysis procedures are complex an process intensive - overlaying multi. vector maps is often time consuming Pro Raster -Simple data structure - Efficent for RS or scanned data - Simple spatial analysis procedures Contra Raster - Requires greater storage space - Graphical output my be less pleasing - Projection transformations difficult Für was steht DTM? Digital Terrain Model (Digitales Geländemodel) Für was steht DEM? Digital Elevation Model (Digitales Höhenmodel) Pro und Contra Device input pro: - fast -Less chance of error - can be done in the field with wireless potential contra: -Requires equipment -More specialist expertise - Limited information Pro und Contra Scanning pro: -Format adaptible - Good for converting paper products.. - fast contra: -Possible distortion errors - Expensive...? -Requires equipment Pro und contra Keyboard entry pro: -Format adaptible -Good for tables of raw data -User understanding contra: - Time consuming -Prone to error Pro und Contra Digitising Pro: -Format adaptible -Good fpr converting paper products contra: - Time consuming - Prone to error - Expensive - Requires equipment Abstracting the real World: Problems to be considered - The real World is dynamic, not static - some features are continuous, some not - The scale of the realworld my not match our data What includes GIS ? -Coordinate systems can be GCS, PCS or VCS - PCS are GCS that habe undergone proj. and given prativular spatial attributes. - The Spatial Reference System of a GIS includes a coordinate system, extents resolution and tolerence

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