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Digital Model Technologies and Applications: The DEM Users Manual, 3rd Edition David F. Maune, PhD, CP and Amar Nayegandhi, CP, CMS

1 | Coastal GeoTools Conference February 8, 2017 1st edition (2001) & 2nd edition (2007)

2 | Coastal GeoTools Conference February 8, 2017 DEM status in 2007 (2nd edition)

• We had no DEM standard products other than the lower- resolution National Elevation Dataset (NED)

• We had no national standards or specifications other than the FEMA Guidelines (2’ & 4’ contour accuracy) for the NFIP

• The 2nd edition’s User Requirements Menu and sample SOWs helped users develop their own non- standard DEM products

3 | Coastal GeoTools Conference February 8, 2017 Progress during the past decade • 2010: USGS’ draft Lidar Guidelines and Base Specifications, V.13 • 2011: National Enhanced Elevation Assessment (NEEA) • 2012: USGS’ Lidar Base Specification, V1.0 • 2013: USGS’ 3D Elevation Program (3DEP) (QL2 Lidar & QL5 IfSAR) • 2013: ASPRS’ LAS Specification, V1.4, and • 2014: ASPRS Positional Accuracy Standards for Digital Geospatial Data • 2014: USGS’ Lidar Base Specification, V1.2 • 2015: USACE’s EM 1110-1-1000, Photogrammetric and Lidar Mapping • 2016: FEMA’s Elevation Guidance for Flood Risk Analysis & Mapping • 2017: NEEA Update and Coastal/Offshore Elevation Requirements and Benefits Study -- vision for a “3D Nation” from the tops of the mountains to the depths of the sea.

4 | Coastal GeoTools Conference February 8, 2017 rd 3 HydroEdition, from to be published in 2017 IFSAR The 3rd edition supports our vision of a future seamless, consistent, high-accuracy, high-resolution 3D Nation, Merger of sonar w/ topo Topobathy from the tops of the mountains & bathy Lidar Lidar to the depths of the sea, that is cost-effective and up-to- date. This includes submerged topography. Every chapter supports this vision – even the front cover

5 | Coastal GeoTools Conference February 8, 2017 3rd Edition, to be published in 2017

1. Introduction to DEMs 2. Vertical Datums 3. Standards, Guidelines & Specifications 4. The National Elevation Dataset 5. The 3D Elevation Program 6. 7. IfSAR 8. Airborne Topographic Lidar 9. Lidar Data Processing 10. Airborne Lidar 11. Sonar 12. Enabling Technologies 13. DEM User Applications 14. DEM User Requirements and Benefits 15. Quality Assessment of Elevation Data 16. Sample Elevation Datasets

6 | Coastal GeoTools Conference February 8, 2017 Ch. 1: Introduction to DEMs (Dave Maune, Karl Heidemann, Stephen Kopp, Clayton Crawford)

Definitions and terminology Hydrologic surface modeling: Raster, vector, point cloud data • Hydro-flattening DEMs, DTMs, DSMs • Hydro-enforcement Mass points and breaklines (2D, • Hydro-conditioning 2.5D and 3D) Elevation derivatives (hillshades, TINs, , LAS datasets slope, aspect and curvature maps, profiles, cross-sections) Contours Different types of maps 3D surface modeling Different interpolation methods for , virtual reality creating DEMs from TINs

Improved Appendix A (Acronyms), Appendix B (Definitions), and Index

7 | Coastal GeoTools Conference February 8, 2017 Hydro-flattened vs. hydro-enforced

8 | Coastal GeoTools Conference February 8, 2017 Ch. 2: Vertical Datums (Dru Smith)

Reference Surfaces (where is Vertical datums (NAVD88, zero height or elevation?) NGVD29, PRVD02, ASVD02, NMVD03, GUVD04, VIVD09, Sea level and ocean tides IGLD85) Tidal datums (MHHW, MLHW, Horizontal datums (NAD83, MHW, MSL, MLW, MHLW, MLLW) WGS84) The Geoid ( follow the Converting heights/vertical datums rules of gravity) Geoid undulations The Ellipsoid (GPS coordinates follow the rules of geometry) Transformation tools Heights: Future vertical datums resulting from NGS’ GRAV-D and datum • Orthometric heights adjustments (in 2022, all x/y and z • Ellipsoid heights coordinates will change) • Dynamic heights

9 | Coastal GeoTools Conference February 8, 2017 Orthometric heights are what most people call “elevations”

10 | Coastal GeoTools Conference February 8, 2017 Ch. 3: Standards, Guidelines and Specifications (Dave Maune)

FGDC Standards, including: USGS Lidar Base Specification V1.2 • National Standard for Spatial Data Accuracy (NSSDA) NOS Hydrographic Surveys Specifications and Deliverables • Standards for Nautical Charting Hydrographic Surveys NDEP Guidelines for Digital Elevation Data (defines old vertical ASPRS Standards & Specs: accuracies: FVA, CVA and SVA) • Positional Accuracy Standards USACE EM 1110-1-1000, for Digital Geospatial Data Photogrammetric & Lidar Mapping (defines new vertical accuracy classes w/ NVA and VVA) Geodetic Control Standards and Guidelines • LAS Specification, V1.4

11 | Coastal GeoTools Conference February 8, 2017 USGS Lidar Base Specification, v1.2

QL2 lidar or better -- acceptable for the 3DEP QL3 lidar or worse -- not acceptable for the 3DEP, except for QL5 IfSAR in Alaska

12 | Coastal GeoTools Conference February 8, 2017 IHO standards for depth uncertainty at the 95% confidence level These IHO standards will probably be used by NGS to establish bathymetric lidar equivalents to USGS’ topographic lidar Quality Levels (QL0, QL1, QL2 and QL3) with:

QL0B (IHO Special Order) QL1B (IHO Special Order) QL2B QL3B QL4B (IHO Order 1a)

13 | Coastal GeoTools Conference February 8, 2017 Ch. 4: The National Elevation Dataset (Dean Gesch, Gayla Evans, Michael Oimoen, Samantha Arundel)

Background, rationale, history The National Elevation Dataset and acronym (NED) were retired Specifications and production when the 3D Elevation Program Source data (3DEP) became operational

Production processing Current developments and future Spatially referenced metadata directions Accuracy and data quality USGS is developing a new line of science products known as the • Absolute vertical accuracy Coastal National Elevation • Relative vertical accuracy Database (CoNED) which integrates recent high resolution Comparison with other large-area coastal lidar data (both topo and elevation datasets bathy) and a temporal component from captures on different dates Applications

14 | Coastal GeoTools Conference February 8, 2017 Coastal National Elevation Database (CoNED)

15 | Coastal GeoTools Conference February 8, 2017 Ch. 5: The 3D Elevation Program (3DEP) (Jason Stoker, Vicki Lucas, Allyson Jason, Diane Eldridge, Larry Sugarbaker) Background, rationale, history Broad Agency Announcement (BAA) process USGS commitment to manage national elevation data assets Acquisition trends Assessment of requirements and 3DEP data quality assurance Benefit/Cost Analysis (NEEA) 3DEP development, based on 3DEP products and services QL2 lidar, 8-year cycle, + QL5 3DEP data dissemination IfSAR for Alaska Data acquisition procedures Current development and future directions: U.S. Interagency Elevation Inventory (USGS and NOAA) • Geiger-mode lidar USGS Lidar Base Specification • Single-photon lidar

16 | Coastal GeoTools Conference February 8, 2017 Typical lidar point cloud being collected for the 3DEP

17 | Coastal GeoTools Conference February 8, 2017 Ch. 6: Photogrammetry (J. Chris McGlone)

Sensor types: Post-processing & quality control • Airborne digital systems Data deliverables • Enabling technologies Project planning considerations Calibration procedures Georeferencing & aerotriangulation Capabilities and limitations Photogrammetric data collection Comparisons with competing / methods: complementary technologies • Softcopy stereoplotters DEM user applications • Manual elevation compilation Cost considerations • Automated elevation collection Technological advancements • Semi-global matching (SGM) • (SfM)

18 | Coastal GeoTools Conference February 8, 2017 True-ortho vs. standard ortho

19 | Coastal GeoTools Conference February 8, 2017 Ch. 7: IfSAR (Scott Hensley, Lorraine Tighe) • Technology Overview • IfSAR Present Operating • Developmental History Status • Airborne IfSAR Systems • IfSAR Mapping Techniques • Spaceborne IfSAR Systems • IfSAR Data Post • Comparison with Other Processing Technologies • IfSAR Quality Control • User Applications • IfSAR Data Deliverables • Mapping Alaska – America’s Last Frontier • Cost Considerations • Technology Advancements

20 | Coastal GeoTools Conference February 8, 2017 IfSAR DTM of Alaska hydro features

21 | Coastal GeoTools Conference February 8, 2017 Ch. 8: Airborne Topographic Lidar (Amar Nayegandhi) • Introduction • Developmental History • Basic Concepts • Airborne Lidar Operations • Light and the Electromagnetic Spectrum • Data Processing • Attenuation and Reflectance • Current Sensor Technology • Laser Ranging • Comparison with • Transmit Laser pulse characteristics Overlapping Technologies • Laser Scanning techniques • Discrete return vs. Waveform- • User Applications resolving Lidar • Detection Methodology • Linear vs. Photon-based lidar • 3-D Flash Lidar Technology • Geiger Mode Lidar

22 | Coastal GeoTools Conference February 8, 2017 Ch. 8: Airborne Topographic Lidar

23 | Coastal GeoTools Conference February 8, 2017 Ch. 9: Lidar Data Processing (Josh Novac) • Introduction • Manual Processing Options • Lidar Processing • Lidargrammetry • Concepts and Approaches • Elevation Conflation • Automated Filtering • DEM Processing • Filtering Ground/Non-Ground points • Noise • Concepts and • Structures Approaches • Vegetation • Processing Techniques • Other above ground features • Terrain • Manual Editing • Point Cloud • Other • Breakline Processing • Incorporating Breaklines • Concepts and Approaches • Hydro-Flattening • Automated Processing Options • Hydro-Conditioning • Water • Hydro-Enforcement • Structures • DSM Processing • Other

24 | Coastal GeoTools Conference February 8, 2017 Ch. 9 Lidar Data Processing Lidar Processing Breakline Processing

Two examples of Lidar classification. The top picture represents a Two examples of breakline extraction. The top higher level of classification including vegetation and buildings. image represents detailed breaklines extracted The bottom example shows ground/non-ground and water using automated methods in eCognition. The classified. bottom represents ponds collected through a combination of automated and manual methods.

25 | Coastal GeoTools Conference, February 8, 2017 Ch. 9: Lidar Data Processing

DEM Processing

26 | Coastal GeoTools Conference February 8, 2017 Ch. 10: Airborne Lidar Bathymetry (Jennifer Wozencraft and Amar Nayegandhi) • Introduction • Developmental History • Bathymetric vs Topobathymetric Lidar • Data Processing • Basic Concepts • Refraction at air/water interface • Expectations from ALB • State of the sea surface Systems • Bubbles and breaking waves • ALB Eye Safety Features • Optical properties of the water column • Depth Penetration & • Beam attenuation coefficient, Diffuse Accuracy Attenuation Coefficient (Kd) and the • Current Sensor Technology Secchi Depth • Characteristics of the sea floor • Comparison with Overlapping Technologies • Basic System Design • Laser Transmitter Unit • User Applications • Scanner Unit • Receiver Unit • Enabling Technologies

27 | Coastal GeoTools Conference February 8, 2017 Ch. 10: Airborne Lidar Bathymetry

AMPLITUDE

Volume Backscatter Surface

∆ (Interface) t Return Detection Points

Bottom Return TIME

28 | Coastal GeoTools Conference February 8, 2017 Ch. 11: Sonar (Guy Noll)

Technology overview Present operating status: Developmental history Platforms and installation Basic principles of acoustic Calibration procedures mapping: Planning considerations • Acoustic sources Capabilities and limitations • Directional transmit/receive Comparisons with complementary transducers and competing technologies Types of sonars: Post processing • Vertical beam sonar Quality control • Multibeam sonar Data deliverables • Side scan sonar Cost considerations • Interferometric/focusing/Doppler Technology advancements

29 | Coastal GeoTools Conference February 8, 2017 Individual beams in a multibeam transducer form a swath

30 | Coastal GeoTools Conference February 8, 2017 Ch. 12: Enabling Technologies (Bruno Scherzinger, Joe Hutton, Mohamed Mostafa) GNSS positioning technologies: GNSS-aided Inertial Navigation technologies (GNSS-AINS): • GNSS single point positioning • Inertial navigation systems (INS) • Differential GNSS • GNSS-AINS for direct • Precise phase georeferencing positioning Direct georeferencing systems for • Precise point positioning (PPP) airborne DEM generation Local, regional and global • Types of airborne DG systems differential GNSS • Boresight calibration Continuously Operating Reference Stations (CORS) • Post processing Types of sensors Motion sensing system for multibeam sonar bathymetry Error sources • Types of sensors

31 | Coastal GeoTools Conference February 8, 2017 IMU-GNSS and Camera-GNSS lever arm calibration

32 | Coastal GeoTools Conference February 8, 2017 Ch. 13: DEM User Applications (Dave Maune) NEEA’s 27 Business Uses Transportation applications (land, aviation and marine General mapping applications navigation and safety) (digital , topographic maps, flood maps) Technical applications (national resources conservation, H&H Special mapping applications modeling, water supply, (soils, geologic, wetland, , stormwater, subsidence) wildlife habitat, cultural resources, urban and regional planning maps) Military applications Coastal mapping applications Commercial applications (Digital Coast, SLR viewing, (, mining, shoreline delineation, coastal renewable energy, oil and gas, management and , telecommunications, recreation) coastal flood hazard mapping) Individual applications (elevation Underwater applications certificates, individual parcel topographic maps)

33 | Coastal GeoTools Conference February 8, 2017 Includes graphic examples of 27 Major Business Uses in the NEEA

These Business Uses did not include general mapping applications or individual applications

34 | Coastal GeoTools Conference February 8, 2017 Ch. 14: DEM User Requirements and Benefits (Dave Maune) DEM User Requirements: Benefits of 3DEP Standard Prod: Need for all users to focus on • Single authoritative source of high standardized QL2 lidar or better, quality & consistent 3DEP data at standard 3DEP deliverables: lower costs to all • Standard metadata • Standard 3DEP products that use common hardware/software, • Standard raw point cloud standard training for data users • Standard classified point cloud and producers • Standard hydro-flattened, bare- • Easier generation of derivative earth raster DEM products from standard source • Standard breaklines • >5:1 Return on Investment • Planned data updates • Common data upgrades that do not compromise standardization • Seamless data from tops of and interoperability mountains to depths of the sea

35 | Coastal GeoTools Conference February 8, 2017 Highest ROI from QL2 Lidar with 6-10 year update cycle

B/C Ratio >5:1 computed using conservative benefits ($1.3B/yr)

B/C Ratio >50:1 if computed using potential benefits ($13.3B/yr)

Actual B/C Ratio is increasing as Lidar costs are decreasing substantially

36 | Coastal GeoTools Conference February 8, 2017 Ch. 15: Quality Assessment (Jen Novac, 100-page tutorial approved by Karl Heidemann, incl. 96 images) Standards, Guidelines and Specs • Macro level review of DEM data Quantitative Assessments: • Micro level review of DEM data: • Accuracy assessments (relative • DEM visualization and display and absolute vertical accuracy) • DEM raster types (DSMs, bare- • Absolute horizontal accuracy earth DTMs, bathymetric and topobathymetric DEMs) assessments • Qualitative reviews • Accuracy reporting • Artifacts/over-smoothing Qualitative Assessments: • Inconsistent editing • Source data QA/QC • Hydro-flattening or enforcement • Breakline QA/QC • Edge-matching • Breakline completeness • QA/QC of contours • Breakline variance • QA/QC of metadata • Breakline topology

37 | Coastal GeoTools Conference February 8, 2017 Boresight / Calibration

38 | Coastal GeoTools Conference February 8, 2017 ΔZ Ortho Relative Accuracy Eval.

39 | Coastal GeoTools Conference February 8, 2017 “Floating” hydro breakline vertices (just one of dozens of hydro issues explained)

40 | Coastal GeoTools Conference February 8, 2017 Bridge Removal Interpolation Artifact (aka “Bridge Saddle”)

Lidar projects processed to USGS specifications must have “bridge saddles” corrected and removed in the final bare earth DEMs to create a continuous surface beneath the bridge.

41 | Coastal GeoTools Conference February 8, 2017 Building Removal Interpolation

42 | Coastal GeoTools Conference February 8, 2017 Hardcopy and eBook

ASPRS is no longer printing hardcopy books or maintaining a warehouse of books for sale.

Dewberry is paying for the layout and printing of limited hardcopies, 500 copies of which will be sold by ASPRS and mailed by Dewberry.

ASPRS will arrange for low-cost eBooks to be sold and distributed (by Amazon or others) directly to students and other users.

We hope to have both versions available for sale by June, 2017.

43 | Coastal GeoTools Conference February 8, 2017