U.S. Department of the InteriorU.S. Geological Survey

Data Integration of Layers and Features for The National Map

March 31, 2003

E. Lynn Usery Michael P. FinnMichael Starbuck

usery@usgs.gov

mfinn@usgs.gov

mstarbuck@usgs.gov

Outline

Motivation, Goals, and Objectives Approach Data Test Sites Methods Products Conclusions

Motivation and Goals

The National Map will consist of integrated datasets, a digital product similar to the comprehensive, integrated lithographic printed map

Current USGS digital products (DLG, DOQ, NED, NHD, NLCD) are single layer and not vertically-integrated

The goal is to develop procedures for automated integration based on metadata

Objectives

Framework for layer integration based on metadata

Framework for feature integration Example results for Atlanta and St. Louis

Approach

Layer-based• Use existing seamless datasets• Determine integration feasibility based on resolution

and accuracy Feature-based

• Implement integration on feature by feature basis• Use developed feature library

Data

Orthoimages from 133 Urban Areas National Hydrography Dataset (NHD) National Elevation Dataset (NED) Transportation (DLG) National Land Cover Dataset (NLCD)

Data Integration Layer Sources

AccuracyResolutionTypeSourceNM Layer

2-10 m 30 mRasterNEDElevation13 m--VectorNHDHydrography1 ft1 ftRaster133 Urban AreasImages60 m30 mRasterNLCDLand CoverVarious--Vector133 Urban AreasTransportation

Test Sites

St. Louis, Missouri• Initially the Manchester and Kirkwood quadrangles

Atlanta• Initial area in Northeast in Gwinnett County

Methods

Layer integration• Determine compatible resolutions and accuracies and

use metadata to automatically combine appropriate datasets

• Determine transformations possible that integrate datasets of incompatible resolutions and accuracies

• Determine limits of integration based on resolution and accuracy

Integration Possibilities

ToleranceFeature MatchingAccuracyData typesNeededNoPoint to pointSameVector/vector1YesPoint to pointsDifferentVector/vector2YesPoint to pointsSameVector/vector3YesPoints to pointsDifferentVector/vector4NoPixel to pixelSameRaster/raster5YesPixel to pixelDifferentRaster/raster6YesPixels to pixelSameRaster/raster7YesPixels to PixelDifferentRaster/raster8NoPixel to pointSameRaster/vector9YesPixel to point(s)DifferentRaster/vector10YesPixel to pointSameRaster/vector11YesPixels to pointsDifferentRaster/vector12

Cartographic Transformations from Keates

Sphere to plane – projection• Mathematical, deterministic, correctable

Three-dimensional to two-dimensional• Mathematical, deterministic, correctable

Generalization• Non-mathematical, scale dependent, humanistic, not

correctable

Mathematical Transformations -- Scale and Resolution Matching

If data meet NMAS, then integration can be automated based on the scale ratios

• If linear ratios of scale denominators are ½ , then integration is possible through mathematical transformations

• For ratios smaller than ½ , generalization results in incompatible differences

Generalization Issues

Selection – common features may not appear on data layers to be integrated (Topfer’s Radical Law)

Simplification – lines may contain reduced numbers of points and have different shapes

Symbolization – for map sources, symbolization may result in areas shown as lines or points

Induction – features may have been interpolated and appear differently on different sources

Feature Integration

Metadata exists on a feature basis• Accuracy, resolution, source are documented by feature• Use Feature Library with an integration application

Products

Integration methodology for layers and features Test implementations for St. Louis and Atlanta

Conclusions

Data integration of layers for The National Map can only be accomplished with datasets that are compatible in resolution and accuracy

Mathematical transformation can automate integration with limited ranges of scales, but cannot correct generalization differences between datasets

U.S. Department of the InteriorU.S. Geological Survey

Data Integration of Layers and Features for The National Map

March 31, 2003

E. Lynn Usery Michael P. FinnMichael Starbuck

usery@usgs.gov

mfinn@usgs.gov

mstarbuck@usgs.gov