On Some Fundamental Geographical Concepts 176B Lecture 3

Nystuen, J. D. (1963) “Identification of some fundamental spatial concepts” Search for a common geographical terminology to eliminate redundancy Basics: Distance, pattern, relative position, site and accessibility Advantages of abstract models and assumptions, e.g. isotropic surface

The mosque floor

Geographic primitives G = g (x, y, z, s, A, t) [x, y, z] = f(  d  Geography also highly dependent upon model

UCSB Lat: Lon:

Projection, datum etc. for a 7.5 min quad

GIS basic geometric functions A GIS package must be able to move between –map projections –coordinate systems –datums –Ellipsoids A GIS must be able to GEORECTIFY Not always a simple task!

Orthorectification

Georegistration: Control

Georectification

Conflation

Address matching 2123 South Main St. Anywhere CA ,312,205mN 623,864mE 15N

Geographic information fundamentals 1. Volume 2. Dimensionality 3. Continuity

Volume 1 meter pixel 24 bit depth (8 bit R, 8 bit G, 8 bit B) California 3 rd largest State A=158,706 square miles A= 411,046,653,039 square meters N=9.865x10^10 bytes 98 gigabyte image

Volume Issues: Tiles and Pyramids

Dimensionality Simple geographic features can be used to build more complex ones. Areas are made up of lines which are made up of points represented by their coordinates. Areas = {Lines} = {Points}

Areas are lines are points are coordinates

Continuity Attributes of the earth fall into different spatial “behaviors” over space and time Many phenomena are best treated as continuous fields –E.g. air temperature, atmospheric pressure, population density Others have distinct spatial extent or edges –E.g. census tracts, buildings, roads

Field vs. Feature (object)

Fields are often rasters

Air Photos Discontinuous irregular rasters: resampling 1929

Features are often vectors

Properties of Features Size Distribution/density Shape Scale Orientation

Size: Resolution and Extent 10cm, 25cm, 50cm, 1m

Resels: Non-uniform Support

Data structure conversion

Distribution

Geographical Clustering

Clusters on points/networks

Shape

Shape vs. Support

Shape measures/analysis

Scale: RF vs. Detail Santa Barbara

Scaling behavior

Orientation: Objects & Frame

Tobler’s First Law of Geography “Everything is related to everything else but near things are more related than distant things” (Tobler, 1970) Variation of (x 1 – x 0 ) 2 Spatial autocorrelation Violates assumptions of statistics

Geographical relations Among features –Contains/overlaps/intersects –Contiguity/Adjacency –Proximity –Trajectory Within fields –Neighborhood relation –Pattern –Process

Vector polygon overlay O =

Raster overlay 0 1 & =

Buffering

Pattern

Pattern (Fourier) Analysis

Contiguity (Clear Lake, Iowa)

Semivariogram

Most important, process… G = g (x, y, z, s, A, t) t0t0 t1t1 t2t2 t3t3

Strands

Time-Space dynamics

Dynamics FROM TO

Geography The study of the earth and its features and of the distribution of life on the earth, including human life and the effects of human activity.