# Presentation: 065381

## Data Integration of Layers and Features for The National Map

**March 31, 2003**

-  E. Lynn Usery
-  Michael P. Finn
- Michael 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

**Notes:**
Data
Source
Type
Resolution
Accuracy
NM Layer
Elevation
NED
Raster
30 m
2-10 m 
Elevation
Hydrography
NHD
Vector
--
13 m
Hydrography
Images
133 Urban Areas
Raster
1 ft
1 ft
Orthoimagery
Land Cover
NLCD
Raster
30 m
60 m
Land Cover
Transportation
133 Urban Areas
Vector
--
Various
Transportation
Data
Source
Type
Resolution
Accuracy
NM Layer
Elevation
NED
Raster
30 m
2-10 m 
Elevation
Hydrography
NHD
Vector
--
13 m
Hydrography
Images
133 Urban Areas
Raster
1 ft
1 ft
Orthoimagery
Land Cover
NLCD
Raster
30 m
60 m
Land Cover
Transportation
133 Urban Areas
Vector
--
Various
Transportation

## Test Sites

- St. Louis, Missouri
- Initially the Manchester and Kirkwood quadrangles
- Atlanta
- Initial area in Northeast in Gwinnett County

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## 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

## 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 1⁄2 , then integration is possible through mathematical transformations
- For ratios smaller than 1⁄2 , 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

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## Feature Integration

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

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## 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

## Data Integration of Layers and Features for The National Map

**March 31, 2003**

-  E. Lynn Usery
-  Michael P. Finn
- Michael Starbuck

- usery@usgs.gov
- mfinn@usgs.gov
- mstarbuck@usgs.gov