Geog 620 - Geographic Information Systems
Study Guide for Exam # 1 (Spring '99)
Italics indicate special reference to assigned readings -- either additional detail is found in text, or in a few cases topics not discussed in class.
Introduction to GIS & related concepts
Definitions of GIS (process-oriented, application, toolbox, database)
GIS data: temporal, spatial & attribute; discrete objects vs. continuous data
raster vs. vector data structures: appropriate for what data?
History of GIS (50s: UW (Tobler, Bunge, Berry, Marble) – spatial statistics & computer cartography; 60s: CGIS, Harvard Lab for Computer Graphics & Spatial Analysis, McHarg’s Design with Nature; Census Bureau & topology)
levels of measurement
Introduction to Vector Mode GIS
& Arc/Info
The coverage
Topology
- arcs (chains), nodes, etc. dangling, pseudo
- arc/node/arc & arc/polygon relationships: connectivity & contiguity
- left and right polygons, from and to nodes
- polygons created from labelpoints and arcs
Other structures: raster
Organizing data into workspaces
Spatial Data Automation & Topology
Input Devices Scanners & Manual Digitizing; Direct use of scanned raster data;
Automation Process --
- Manuscript preparation (what are requirements for manuscript)
- Data Entry: manual digitizing, keyboard entry, mouse (& differences)
digitizing and editing tools & methods
- spaghetti vs. arc-node digitizing;
- scale and generalization concepts -- levels of generalization and tolerances (node, fuzzy, dangle length)
- meaning of fuzzy tolerance in terms of minimum mapping unit
- balance between ease of use and accuracy
- generalization using Douglas-Peucker algorithm
- ArcEdit tools: environment settings, selections, slivers, snapping
- Arcedit operations (disp, coord, drawe, backcov, backe, nodesnap, arcsnap, snapcov, snapfeature, intersectarcs, mape, selection commands, extend, spline, generalize, calc, list, items, moveitem)
topology creation and errors
- topological errors
- Arc operations (build, clean, labelerrors, generate, matchnode, relate)
- Understand the standard items in feature attribute tables (PAT and AAT)
- Understand the differences among the various types of selection commands (reselect, nselect, unselect, aselect)
attributing
- use of user id / $id
- topology building > attribute table
- adding items
- database methods : tabular entry, table joining
- arcedit methods : selection + calc
other data entry methods
- scanning, field, imagery (interpretation), heads up digitizing, published data, text generate format
- Digitizing and Scanning: scale & resolution concepts.
- Field data: GPS. Geocoding
Spatial Transformation & Map Projections
spatial reference systems & coordinates (spherical & plane = cartesian)
control and measurement; resolution and accuracy; lineage
GIS requires cartesian coordinates based upon:
projections (mathematically defined relative to geographic spherical coordinates).
Parameters: things like standard parallels, central meridians, false northing/easting.
Types of projections (mostly review of 103): azimuthal, cylindrical, conic; standard parallels; graticule; UTM: zones, central meridian; State Plane
Datum: NAD27 vs. NAD83; associated spheroids Clarke 1866 vs. GRS 1980
Geometric transformation process -- affine vs. projective methods, accuracy,
meaning of accuracy measurement -- RMSE; relationship with scale; Transformation does: rotation, translation, and scaling (& meaning of each). Registration, rubber sheeting
Uses for PROJECT <FILE | COVER>
transformation vs. projection -- know the difference.
Existing Map Data: networks, ftp, USGS (DLG, DEM, GIRAS, DOQ, DRG), Map Merging & Rectification
- edgematching, rubbersheeting & Arcedit ADJUST, links (node, free, identity), autolink, limitadjust, snapping environment, mapjoin vs. append commands
Database Management & Query
Relationships of Graphic and Nongraphic Data
Attribute and expansion tables: standard items in PAT, AAT. significance of internal and user ids.
Item/field definition : types, bytes
Arc commands: joinitem, additem, dropitem, pullitems, statistics, relate
Statistics and frequency operations
Info commands: add, list, items, define, relate.
Format and use of a lookup table!!!
Basic Database Management and Query; Searches by attribute; searches by geography; the query interface
Geographical matrix & flat files
other concepts
measurement framework vs. representation