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C. Brewer et al. ICC2009, November 2009

Evaluating Generalizations of Hydrographyin Differing Terrains for The National Map

of the United States

Cynthia Brewer, Pennsylvania State UniversityBarbara Buttenfield, University of Colorado—Boulder

E. Lynn Usery, CEGIS, U.S. Geological Survey

Research Assistants:Chelsea Hanchett and Paulo Raposo, Penn State

Mamata Akella, PSU→ESRIChris Anderson-Tarver and Jochen Wendel, CU-Boulder

TNM data prep: NHD programming: Much advice:Tom Hale, USGS Larry Stanislawski, USGS Charlie Frye, ESRI


Scope

Multiscale topographic mappingGeneralization of National Hydrography Dataset

(1:24,000 High Resolution NHD)Multiscale topographic map designFor USGS web delivery portal The National Map (TNM)

Scale range 1:20,000 – 1:200,000 (1:5K – 1:2M planned)

Why focus on hydrography? Highly sensitive to scale and landscape differencesCommonly displayed on most base maps


Objectives

Work toward full automationMinimize anticipated times for manual editingUse COTS software or USGS available code

Maximize efficiency Make no more generalized data versions than necessaryLevel of detail (LoD) data

Preserve important hydrographic/cartographic differencesTerrain differences – flat, hilly, mountainousNext: climate impacts – humid, dry


Humid —Flat: Upper Suwannee, FL-GAHilly: Pomme de Terre, MOMountainous: South Branch Potomac, W V

Dry —Flat: Lower Beaver, UTHilly: Lower Prairie Dog Town Fork Red, TXMountainous: Piceance-Yellow, CO

Urban — St. Louis, MO; Atlanta, GA

Landscape Types

Subbasin Sample

Four in Iowa:

North and South Raccoon, Middle Des Moines, and Lake Red Rock


Evaluating the solutionsContextual

– Map series across range of scales– Critique by domain experts (hydrologists, cartographers)

Validation– Compare against 100K Medium Resolution NHD

Metric– Summary statistics on retained geometry– Channel length, network local density– Catchment areas, upstream drainage


Building an LoD — 3 case studies

A. Isolate a single, continuous centerline– Intersect NHD Flowlines with NHD Areas– Dissolve on GNIS name– Simplify

B. Identify NHD Flowlines by local density– Prune differentially– Simplify, concatenate

C. Isolate local textures from NHD Areas / Waterbodies– Analyze, aggregate, simplify or smooth– May require treating feature codes individually


Case Study A:Isolate a single

continuous centerline

Pomme de Terre River,

Missouri—

humid - hilly

We are almost there…


Pomme de Terre, MO — NHD 24Khumid - hilly

3. Prune and simplify flowlines

2. Primary and secondary centerlines

1. Select and simplify waterbodies and areas


Draft result — MO 50K LoD mapped at 100K

Derived 50K LoDHigh resolution (24K NHD)


Validation

Derived 50K LoDMedium resolution (100K NHD)


Missouri series with data from

The National Map– 24K map

ArcGIS to JPEG to screen capture


Missouri, 50K map with 24K hydro

Missouri50K map with

24K hydro

1

3

24


Missouri, 50K map with 50K LoD

Missouri50K map with

50K LoD hydro

Visual evaluation of hydro in map

context

1

3

24


Missouri 50K LoD and original 24K hydro


Case Study B: Identify NHD

Flowlines by local density

South Branch Potomac River,West Virginia

—humid -

mountainous


What is meant by local density …


S. Br. Potomac, WV — NHD 24Khumid - mountainous

3. Isolate non-centerline flowlines

1. Prune differentially, merge, build diffs_file

2. Intersect NHD flowlines with NHD areas / waterbodies to delineate centerlines

4. Simplify

Pruning criterion: Summed remaining stream channel lengthSummed original catchment area


1. Prune differentially, merge, build diffs_file


Draft result — WV 50K LoD mapped

At 100K: With original 24K hydro With derived 50K LoD

C. Brewer et al. ICC2009, November 2009At 100K: With original 100K hydro With derived 50K LoD

Draft result — WV 50K LoD mapped


West Virginia series from TNM – 24K

West Virginia series with data from

The National Map– 24K map


West Virginia, 80K

West Virginia 80K


West Virginia, 200K

West Virginia 200K


Case Study C:Isolate local textures from NHD Areas and

Waterbodies

Upper Suwannee River,

Florida-Georgia—

humid - flat


Upper Suwannee, FL-GA — NHD 24Khumid - flat

1. Swamp / Marsh

2. Lakes / Ponds


1. Swamp/ Marsh


Florida-Georgia, 80K map with 24K hydro

Florida-Georgia, 80K map with

24K hydro


Florida-Georgia, 80K map with 50K LoD

Florida-Georgia, 80K map with

50K LoD hydro


The National Map: eight themes

• elevation• land use / land cover• boundaries• transportation• structures• hydrography• geographic names• orthoimagery

nationalmap.gov New Viewer announced for December


Practical considerations in design development

• No custom edits on TNM data (no clean up)• Simple geometric symbols, so no missing fonts or

pictures on export• Regular fonts for export and file sharing (vs. USGS look

with Souvenir and Univers)• Lots of group layers to easily turn off categories while

evaluating appearance• All rasters and layers with transparency at bottom of

TOC so export retains editable vectors and type• No over/under passing on bridges and ramps (user may

query this detail using GeoPDF click out to Google)


Color contrasts

• Red roads vs brown contours – use gray contours


Color contrasts

• Red roads vs brown contours – use gray contours• All colors lighter than black labels – few halos

(only blue hydro labels and green reservation labels use halos)


Color contrasts



• This is not a road map – do not use whole contrast range on road categories


Color contrasts




• Contrasting outlines on point symbols separate from each other and background


Color contrasts




• Contrasting outlines on point symbols separate from each other and background

• Leave contrast available for update and overlay of operational information– magenta could be used for additions if no magenta symbols


Systematic color categories for symbols

Rd

YG

Pu Cy

Bu

Or

Yl

Gntransportationbuilt-up areas

wooded areasforest reservesparks

hydrography

points:emergencyhospitalsschools

Gy

boundaries

Br

Human themes: Natural themes:admin reserveshillshade


100K

24K

Multiscale durability:good point overlaps


Hydrography

• Label with a paired layer, classed differently (not symbolized)

• More level-of-detail (LoD) databases in development(if 50K LoD covers 50-200, does 200K LoD cover 200-800?)

• Tapered by symbolizing upstream drainage area (stream order not useful)

• Intermittent and perennial symbolized


Representing stream hierarchy

Class upstream drainage area attribute and represent by width and color


Stream tapering

Width (pts) RGB

lighter0.50 100,180,2000.75 100,180,200

med blue1.00 50,165,2001.35 50,165,200

darker1.70 0,150,2002.00 0,150,200


Multicolor hillshade with transparency


Additional workGeneralization sequences for additional landscapes: settlement patterns (rural vs. urbanized) and coastal

Tailor generalization algorithms, parameters, sequences to landscape types

Decide the smallest number of tailored solutions that will apply to any generalization situation, nationally.Confirm they are not interchangeable through testing

Test topo designs in multiple formats (ArcGIS, GeoPDF, cached tiles for web services, print) and multiple resolutions (print, 96 ppi desktop, 130+ ppi laptop)


Funding acknowledgements

USGS Center of Excellence for Geospatial Information Science (CEGIS)

Funded through Department of Interior CESU program, January 2007 to present

ResourcesProject resources: ScaleMaster.orgLynn’s Center: cegis.usgs.govCindy’s website: www.personal.psu.edu/cab38babs’ Meridian Lab: greenwich.colorado.edu

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