Presentation on theme: "Faculty of Engineering Technology Building and Construction Sciences 1 EA141 Module 7 Geographic Information Systems GIS."— Presentation transcript:
Faculty of Engineering Technology Building and Construction Sciences 1 EA141 Module 7 Geographic Information Systems GIS
2 7.1 Information Systems collection of raw data processed to produce useful information Steps observation collection processing (analysis) results decisions e.g. test marks
3 7.2 Geographic Information Systems geographic data = location (x,y,z,t) of: people places things all info in a GIS must be geographically refererenced temporal referencing much more difficult! processing = spatial analysis
4 7.2 GIS vs. IS e.g. where to locate a new donut shop? I.S. … how many donut shops there are in Hamilton G.I.S. … draw me a map showing location of all donut shops in Hamilton GIS uses "spatial analysis" to produce a "smart map" most things we do in GIS could be done with paper maps (dumb maps)… but GIS makes it a lot easier time = $$$ … GIS makes new analyses feasible
5 7.3 GIS and Surveying GIS new data acquisition GIS relies on accurate data Surveying = new data acquisition other fields of Geomatics also contribute: GPS photogrammetry remote sensing
6 7.4 What's it made of? GIS = hardware (computer, printer, etc.) software (MapInfo, ArcInfo, ArcView) data approx. $$cost$$ breakdown: hardware 10-20% software 10-20% data 60-80% data acquisition data entry data scrubbing
7 7.5 Spatial Data all natural or man-made features lines or symbols on maps images on photos "spatial object" = digital representation of real- world "entity" dimensionality… 0-D = (x,y,z) = "point data" 1-D = set of point data = "line data" 2-D = closed sets of lines = "area data" 3-D = "volume data"
8 7.5 Spatial Data - Dimensionality 0-D = (x,y,z) = "point data" = position only e.g. manhole traffic light well donut shop 1-D = set of point data = "line data" e.g. roads sewers property lines stream
9 7.5 Spatial Data - Dimensionality 2-D = closed sets of lines = "area data" e.g., building footprint park wooded area land zoned "commercial" 3-D = "volume data" e.g., gravel quarry cut/fill area oil/gas deposit
10 7.5 NON-Spatial Data a.k.a. "attribute data" = any other characteristics that pertain to an entity e.g. ownership soil type age of structure material e.g. water well spatial data = point data = 0-D = location non-spatial data = owner's name, drill date, depth, etc.
11 7.6 Data Models what data needs to be included in the GIS? depends on end-uses depends on budget $$$ two types of data models Raster (dumb) = 0-D Vector (smart) = 1-D to 3-D
12 7.7 Topology branch of math describing relationships between spatial objects topological relation may be: connectivity (connected to another object) directionality (before or after another object) adjacency (beside another object) nestedness (inside another object)
13 7.8 Analysis - Buffering common analytical function of GISs area around an object think of AutoCAD "OFFSET" command point buffer = area around a point line buffer = area left & right of a line polygon buffer = area around area
14 7.8 Other Analyses adjacency e.g. find neighbouring properties connectivity e.g. find connected watermains, streets to evaluate emergency preparedness overlay MOST COMMON ANALYSIS e.g. show all properties: with no vegetation slope < 5% on clay soil < 15 min from a donut shop
15 7.9 GIS & GPS GPS gives current location of mobile things GIS knows locations of fixed features GIS + GPS tells me: what route will minimize time application to emergency vehicles, police best route from where I am to a donut shop when visiting a new city "the only limit is our imagination"…