140 likes | 262 Views
Modelling Essentials. Model Parsimony vs. Model Simplicity. Thinking Spatially. Begin by thinking about what your [spatial] output will be. You can then subdivide this spatial information product into elements and operators. Recognize spatial patterns.
E N D
Modelling Essentials Model Parsimony vs. Model Simplicity. Modelling Essentials
Thinking Spatially • Begin by thinking about what your [spatial] output will be. • You can then subdivide this spatial information product into elements and operators. • Recognize spatial patterns. • Identify the processes that created the patterns. Modelling Essentials
Visible Patterns Modelling Essentials
Visible Patterns Modelling Essentials
Visible Patterns • Measuring Visible Patterns - Landscape Metrics • # of patches / area • Patch sizes & shapes • Patch densities & inter-patch distances • Isolation metrics • Perimeter-to-area ratios • Orientations Modelling Essentials
Functional Patterns • Not readily visible. • Latent Patterns: • Threshold dependent • Temporally unique Modelling Essentials
Tools for Identifying Patterns • The Landscape • Visual observations by domain experts. • Not necessarily the same as the GIS modeller. • Observations should be made: • At different times of the day; • In different seasons; • From different perspectives; • With different viewing tools. Modelling Essentials
Tools for Identifying Patterns • Literature Surveys • Within-domain surveys. • Extra-domain surveys. • Knowledge Engineering • Domain experts. • Expert Systems. Modelling Essentials
Tools for Identifying Patterns • Maps • Variations in themes, scales, projections, perspectives, dimensionalities, symbolisms … • Aerial Photography • Variations in tone, colour, texture, setting, scale, association, time … Modelling Essentials
Tools for Identifying Patterns • Satellite Imagery • Variations in spectral, spatial, temporal, radiometric resolutions. • Digital image analysis. • Statistical Techniques • Descriptive stats. • Correlation, regression. • Central tendency; spatial dispersion. Modelling Essentials
From Pattern to Process • Recognizing the spatial interactions of the problem • Sometimes determining the underlying processes that created the patterns; sometimes evaluating the effects of existing patterns on on-going processes. Modelling Essentials
From Pattern to Process • Go beyond pattern recognition into pattern description. Demers, M.N., 2002. GIS Modeling in Raster. Wiley. Modelling Essentials
Types of GIS Models • Purpose Models • Descriptive Models • Describe parts or all of a study area. • Passive. • E.g. a map. • Prescriptive Models • Prescribe best solutions. • Active. • E.g. best location analysis Modelling Essentials
Types of GIS Models • Methodological Models • Deterministic • Stochastic • Logistic Models • Inductive • Deductive Modelling Essentials