- Data Input & Editing
- GIS Data Sources
- GIS Map Data (digital)
- base maps (GeoBC topographic)
- thematic maps (Forest Cover, ecosystems, etc.)
- Remote Sensing
-
- energy (sun)
- interacts with earth surface
- travels to satellite sensor
- beamed to receiving stn.
- Field Survey
- GPS
- survey file export (RoadEng)
- Digital Capture
- Keyboard entry
- attribute data - entered in tables
- spatial data - individual coordinates (manual COGO) - rarely done now
-
- what is it?
- steps
- preparation
- tablet (paper map)
- register map
- heads-up
- create/select data layer
- set drafting assists (i.e. snapping)
- digitize
- point - simple ... 1 point
- line
- direction (for streams)
- polygon
- same as line (above)
- series of points
- point mode vs. stream mode
- from paper
-
- trace an image on the screen
-
- what is it?
- steps
- scan (raster)
- vectorize (converts raster - vector)
- georeference
- Editing
- detect & correct errors
- artifacts
- spikes
- loops
-
- poorly traced
- sliver polygons
- under/over shoots
- missing or duplicate features
- update/ maintain database
- Geometric Transformations (combining data)
- convert to same projection
- convert to same datum
- edge matching
- for adjacent maps
- rubber sheeting
- for overlapping maps
- 'incoming map/ image' is stretched to match base map
- Generalizations
- others prev. covered
- combination
- simplification
- exaggeration
- selection (omission)
- displacement
- Topology
- what is it?
- explicit definition of spatial relationships between map features
-
- allows relational analyses
- find neighbours
- routing through networks
- "find all islands"
- enforces data integrity
- eliminates improper linework
- missing or duplicate ID lablels
- end result
- "clean line work"
- each feature has a unique ID label
- adjacency, connectivity and containment are "understood" by the GIS
