Tracy Fuller – U. S. Geological Survey February 24, 2016

U. S. Geological Survey Arctic Elevation Data Involvement

• Statewide Alaska IfSAR Radar Collection Program

• Pan-Arctic Digital Elevation Map International

Coordination

• Incredibly high-resolution

elevation data is being created

for the first time over the entire

Arctic 60-degrees and north,

and all of Alaska and

Greenland

• All the data will be available to

the public for free, unrestricted

use

Arctic Elevation Data

A Digital Elevation Model, or DEM, is a digital representation of terrain

• One common DEM structure is a regular grid of elevation heights

• The ground distance between points is called DEM density or

resolution (examples: 1000m, 100m, 30m, 10m, 5m, 2m – lower

resolution means more detail)

Digital Elevation Model

(graphics from MIT Libraries)

• Generate contours and shaded relief

images for use on maps

• Generate derivative terrain slope and

aspect models

GIS applications/computer simulations: • natural resource management

• wildfire growth forecasting

• glacial studies

• climate modeling

• flood and tsunami inundation modeling

• line of sight

• coastal erosion forecasting

• drainage flow accumulation

• aircraft safety and rescue operations

Common DEM Uses

(graphics from MIT Libraries)

• Digital Surface Model, DSM, shows ‘tops of trees and structures’

• Digital Terrain Model, DTM, removes cover to show ‘bare earth’

Two Common DEM Subtypes

• Airborne or satellite

stereo imagery – position

of sensor and common

point on two images used

to derive elevation

• Airborne or satellite radar

– active radar wave sent

and received from a

sensor

• Airborne lidar – light

pulse sent to earth and

reflection returns to

aircraft

Modern Elevation Collection

• U.S. Geological Survey 3D Elevation Program (3DEP)

• Develop partnerships to collect enhanced elevation data over the

conterminous United States, Hawaii, Alaska, U.S. Territories

• Collect Interferometric Synthetic Aperture Radar (IfSAR) for Alaska

Alaska Radar Elevation Project

Alaska IfSAR Deliverables

Meet 2008 Alaska Statewide

Digital Mapping Initiative

requirements

• 5m elevation grids

• DTM and DSM delivered

• 3.6m vertical accuracy

• Meets National Map

Accuracy Standards for

1:24,000-scale mapping

(20-foot contours)

DSM

DTM

Alaska IfSAR Deliverables

Orthorectified Radar Image (ORI)

• Pseudo image based on radar reflection intensity

• Useful for delineating surface water features, controlling new color imagery collects

• 62.5 cm resolution image pixels

Alaska IfSAR Deliverables

Digital Breaklines

• Delineate ridges, valley bottoms, river banks

• Created to help enforce correct DEM water flow and improve overall DEM quality

• Useful for editing Alaska National Hydrography Dataset

Alaska IfSAR Deliverables

GPS Survey Control Check Points

• Over 800 points being collected statewide

• X, Y, Z locations used to assess IfSAR quality

• Useful for improving and assessing other imagery and elevation projects

Alaska IfSAR Collection Status

• $62M total project cost

• Volunteer contributions from

State of Alaska and Federal

Agencies

• 62% fully funded, will surpass

70% in FY2016

• Attempting to complete

northeast AK summer 2016

• All deliverables being made

available for free to the public

Pan-Arctic Digital Elevation Map

• Arctic Council Initiative, U.S. Chairmanship 2015-2017

• Sponsored to ‘Address the Impacts of Climate Change’

• Proposal Accepted by Arctic Council Spring 2015

• Improve public access to high resolution Arctic

elevation data

• Single point of access

• Arctic Spatial Data Infrastructure, representing the

national mapping agencies of the eight Arctic nations,

coordinate international support to the project

• Arctic Council ‘Conservation of Flora and Fauna’

Working Group (CAFF) to monitor progress

• Polar Geospatial Center ArcticDEM

• Announced by U.S. President September 2015

• Elegant solution to the original initiative

USGS and Arctic SDI Support of PGC ArcticDEM

USGS

• Coordinate international support to Polar Geospatial Center

• Organize series of workshops with Arctic nation representatives

• Interface with Arctic SDI nations and Polar Geospatial Center

• Produce progress reports for CAFF and Arctic Council

• Coordinate international requirements gathering activities

Arctic SDI

• Arctic nations can provide control point data to improve DEM accuracy

• Arctic nations can review data and report issues to PGC

• Arctic nations can edit PGC delivered data and create an improved

national product

• Arctic nations can submit improved data to PGC and other data

distributors in the future