Spatial Data Integration Deana D. Pennington, PhD University of New Mexico

What is data integration? Combining datasets by resolving differences in: Data structures – text vs database Spatial data: vector, raster, tin, contour map Units – inches vs meters Spatial data: plus projections and datums Spatial scales – grain, extent, focus Temporal scales – hourly vs monthly samples Semantics – call the same things different names, or call different things by the same name Context – harmonizing different things that are related 1.Spatial Structures 2.Projections/datums 3.Spatial Scales 4.Example Land Use Tracts Roads Streams Vegetation Species occurrence

Metadata, Metadata, Metadata!

Data Structures: Fields vs Objects Hay et al., 2001 Field perspective Every location has a value Elevation Temperature % vegetation Object perspective Some locations are within the bounds Species occurrence Sample site Streams

Data Structures: Kenneth E. Foote and Donald J. Huebner, The Geographer's Craft Project, Department of Geography, The University of Colorado at Boulder GPS points, lines, polygons Most field data Satellite data Air photos

Data Structures: Converting raster data to vector data (vectorize) Hay et al., 2001 Problems: 1.Fuzzy edges 2.Overlapping objects 3.Error and uncertainty

Classification Band 1 Band 2 Band 3 Soil Veg Water Band 1 Band 2

Spatial Dependence & Error False color composite Maximum Likelihood 89.44%

Data Structures: Converting vector data to raster data: categorical Hay et al., 2001 Nearest neighbor

Data Structures: Converting vector data to raster data: numerical Proximal (nearest point) Linear averaging Non-linear function Kriging (semi-variogram)

Next: 1.Spatial Structures 2.Projections/datums 3.Spatial Scales 4.Example

Coordinate Systems There are many different coordinate systems, based on a variety of reference systems, projections, geodetic datums, and units in use today Kenneth E. Foote and Donald J. Huebner, The Geographer's Craft Project, Department of Geography, The University of Colorado at Boulder

Projections

Projections

Projections

Reference Ellipsoids Ellipsoidal models define an ellipsoid with an equatorial radius and a polar radius. The best of these models can represent the shape of the earth over the smoothed, averaged sea-surface to within about one-hundred meters. Reference ellipsoids are defined by semi-major (equatorial radius) and semi-minor (polar radius) axes.

Datums

Kenneth E. Foote and Donald J. Huebner, The Geographer's Craft Project, Department of Geography, The University of Colorado at Boulder Ellipsoids & Datums ***Referencing geodetic coordinates to the wrong datum can result in position errors of hundreds of meters***

Next: 1.Spatial Structures 2.Projections/datums 3.Spatial Scales: Grain & Extent 4.Example

Study Grain & Extent Hay et al., 2001

Grain in vector data Plot average biomass Site average biomass Biome average biomass State average biomass

Next: 1.Spatial Structures 2.Projections/datums 3.Spatial Scales 4.Example

Elevation (m) Vegetation cover type P, juniper, 2200m, 16C P, pinyon, 2320m, 14C A, creosote, 1535m, 22C Sample 3, lat, long, absence Mean annual temperature (C) Access File Excel File Integrated data: Sample 2, lat, long, presence Sample 1, lat, long, presence Example: Integrating Species Occurrence Points and Images 1.Semantics 2.Compatible scales 3.Reproject 4.Resample grain 5.Clip extent 6.Sample occurrence points

Lab #11 1.Raster/vector conversions 2.Projections 3.Scale change