spatial analysis of vector data Flashcards
GIS analysis
improves mapping by quantifying spatial relationships
general catgories of spatial relationships
measurements: patterns, distances, lengths and areas
proximal: are within a distance of (near, far, absolute)
topological: are spatially identical to? spatially adjacent to?
recoding
commercial/residential –> urban
gardens/farms –> agricultural
old value –> new value
pattern
random
uniform
clustered
toblers first law
challenges with geographical space
not a flat plane
the real length is often more bc of elevation changes
must take account of the effects of altitude
simpsons rule for measuring data
work clockwise from vertices on polygon
positve areas when 1st vertex has lower xvalue than 2nd
negative areas when 1st vertex higher x value than 2nd
proximity analysis
provides a measure of nearness or farness using distance or some other relative measure of distance such as travel time
conducted to evaluate the influence of objects with respect to other surrounding objects
buffering
common form of proximity analysis (noise zones, pollution zones)
simple buffering vs complex buffering
complex buffering
each line segment is buffered based on an attribute
distance is integer or float
can be inner (setback) or outer buffering and boundaries
simple buffering
point, line, polygon
topological (vector overlay) analysis
computationally combine data sets for a new output
not the same as visual overlay or transparency
point in polygon: contained
line in polygon: intersecting
polygon on polygon: adjacent
types of spatial relations
distance, containment, intersection, adjacency
geocoding
process of assigning a point location within a coordinate system
shortest path
finding the min distance or costpath b/w an origin node and a destination node
emergency planning
GIS workflow process
spatial data
data analysis + decision makers
results
