Objectives of Lecture:
Then (attribute combination), produce an output value by applying a rule that uses the neighboring values.
Examples in textbook (Overheads):
Various filters in practical use
The rules can be grouped by combination method and by level of measurement:
Examples of operations on near neighbors | |||
---|---|---|---|
Level of Measurement | Dominance | Contributory | Interaction |
Nominal | Buffer Drop-line aggregation (dissolve) |
Voting tabulation majority filter, diversity, etc. |
Edge
detectors, Explicit combination |
Ordinal (at least) | Max/min of neighbors; (example to count palm trees) | Percentile | Profile, drainage |
Continuous (aspatial) |
Max/min neighbor (population density) (example: Minimum Flying Height: from a max in cell) |
Sum/average ; (a population density example using TOTAL; description) | Edge detectors |
Continuous attribute with horizontal measures | |||
- Slope | Maximum slope | Best fit plane | |
- Distance weighting | Smoothing, filters an example of distance filter (Watts Barr; Amazon) |
Autocorrelation; hillshading (example) [plus behind the scenes AML to accomplish this...] |
|
- Splines: (see below) | Amazon precipitation; (an animated gif) |
Of course these operations are sensitive to error: DesMoines flooding, description.
Some additional depth on the surface modelling [Group was at Army Corps of Engineers CERL, then at University of Illinois; Helena seems to be at North Carolina State now...] The page has moved, and most of the movies, but the links are mostly dead (and point back to Illinois!):