PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
January 2019
9
A N I N T E R V I E W
DEM user requirements and benefits and concluded that the highest return
on investment would come from QL2 lidar nationwide except for QL5 IfSAR of
Alaska. The chapter describes the 3DEP program; the U.S. Interagency Eleva-
tion Inventory (USIEI); the USGS Lidar Base Specifications; the Broad Agency
Announcement (BAA) process; acquisition trends; 3DEP data quality assur-
ance; 3DEP products, services and data dissemination; current developments
and future directions. Figure 9 (previous page) shows 3DEP partnership awards
for FY2018 alone, a major reason why the 3DEP is so popular and successful.
Chapter 6—Photogrammetry
explains airborne and satellite digital imaging
systems; project planning considerations; georeferencing and aerotriangulation;
photogrammetric data collection methods (softcopy stereoplotters, manual and
automated elevation collection); post processing; data deliverables; enabling
technologies; calibration procedures; capabilities and limitations compared
with competing/complementary technologies; DEM user applications; cost con-
siderations; and technological
advancements. It is important
that DEM users understand the
capabilities and limitations of
photogrammetry compared with
lidar and IfSAR, for example.
Figure 10 (right) is an example of
a DEM produced with Structure
from Motion (SfM) photogram-
metry and UAV imagery.
Chapter 7—Interferometric Synthetic Aperture Radar–IfSAR
explains
how interferometric synthetic aperture radar works, airborne and satellite If-
SAR alternatives, how aerial IfSAR is completing the first-ever mapping of
Alaska to specified accuracy standards, and how differential IfSAR/InSAR is
used to monitor subsidence at the mm level. Mapping through clouds with
high-resolution Ortho-rectified Radar Images (ORIs) and able to pan-sharpen
low-resolution
satellite
imagery (with clouds), the
IfSAR statewide mapping
of Alaska will be complet-
ed in 2019, the first time
that Alaska has ever been
mapped to ASPRS accuracy
standards. Figure 11 (right)
shows the hydrographic
feature detail of IfSAR
data.
Chapter 8—Airborne Topographic
Lidar
explains the basic concepts of
topographic lidar scanning and sen-
sors; compares traditional linear-mode
lidar with photon-sensitive and Gei-
ger-mode lidar; boresight calibration;
airborne lidar project planning; and the
status of current lidar sensor technolo-
gies from Teledyne Optech, Leica Geo-
systems, Riegl, and Harris Corp. Figure
12 (right) shows a typical lidar aircraft
with GPS and IMU, scanning the ter-
rain beneath.
Chapter 9—Lidar Data Processing
explains concepts and ap-
proaches to automated filtering of lidar point clouds to include
ground and non-ground points, noise, vegetation, structures and oth-
er above-ground features; manual editing of lidar; breakline process-
ing to include area and linear hydrographic features, structures, man-
ual review and editing; elevation assignment to breakline features, to
include linear and area hydrographic feature elevation assignment; DEM
processing concepts and approaches, processing techniques, incorporat-
ing breaklines; DSM
processing; and other
derivative
products
including
contours.
Figure 13 (right) demon-
strates procedures for
hydro-enforcement and
continuous downsteam
flow (monotonicity).
Chapter 10—Airborne Lidar Bathymetry
explains the basic concepts
of bathymetric lidar scanning and sensors; system design; data processing
including system calibration; output formats and deliverables; and the sta-
tus of current sensors including SHOALS, CZMIL, LADS, Chiroptera II/Hawk
Eye III, EAARL, VQ 820/880-G, and Titan; operational and planning consider-
ations; and comparisons with overlapping technologies. Figure 14 (below)
demonstrates the bathymetric surface detail of this dataset produced by
Dewberry for the NOAA Office for Coastal Management.
Chapter 11—Sonar
provides a technology overview and developmental
history of acoustic mapping and explains the basic principles used, to include
acoustic sources and directional transmit/receive transducers. It explains the
different types of sonars (vertical beam, multibeam, side scan, interferomet-
ric, focusing, and Doppler); present operating status; platforms and installa-
tion; calibration procedures; planning considerations; capabilities and lim-
itations and comparisons with complementary and competing technologies;
post processing, quality control, data deliverables, cost considerations, and
technology advancements. Figure 15 (below) demonstrates a sonar product
used for safety of maritime navigation.
