Asemi-Major Axis of the Earth S Ellipsoid

EM 1110-1-1000

30 Sep 2013

APPENDIX B

Glossary

B-1.Notation

aSemi-major axis of the Earth’s ellipsoid

bSemi-minor axis of the Earth’s ellipsoid

BAir base between consecutive exposure stations in a strip of aerial photographs or digital images

fCamera focal length

fFlattening of the Earth’s ellipsoid where f = (a – b)/a

hEllipsoid height, the height above or below the reference ellipsoid, as measured along the normal (perpendicular) to the ellipsoid at the point and taken positive upward from the ellipsoid

iInteger value

HOrthometric height, the height above the geoid as measured along the plumbline between the geoid and a point on the Earth’s surface, taken positive upward from the geoid; commonly called the “elevation”

NGeoid height, the difference between an ellipsoid height and an orthometric height (N = h – H) of a point on the Earth’s surface.

nNumber of integers in a series, often used in formulas where i varies from 1 to n.

oFocal point of camera lens

rRadial component of a measurement, such as the radial distance from the principal point to an image point, the radial component of an RMSE calculation (RMSEr), or NSSDA radial accuracy at the 95% confidence level (Accuracyr).

SPhoto or map scale

WThe ground distance between adjacent flight lines

x,yPhotocoordinates

x0,y0Principal point photocoordinates

xp,ypPhotocoordinates of point p on an image (point P on the ground)

XP,YPGround coordinates of point P

x/y/z3-D coordinates in the air, obtained directly from airborne GPS or indirectly from aerial triangulation, normally used to identify the 3-D position of the focal point of a camera at the instant an aerial photo or image is taken, or the instant when a LiDAR or IFSAR pulse is emitted; these coordinates provide half of the six exterior orientation parameters used for mapping by photogrammetry, lidargrammetry or radargrammetry. See also ω,φ,κ.

XThe distance along the X-axis from the origin of a 2-D or 3-D Cartesian coordinate system. An X-coordinate is the first half (the Easting) of UTM or State Plane Coordinates

YThe distance along the Y-axis from the origin of a 2-D or 3-D Cartesian coordinate system. A Y-coordinate is the second half (the Northing) of UTM or State Plane Coordinates

ZThe distance along the Z-axis from the origin of a 3-D Cartesian coordinate system. Note, this is not the same as the elevation or height above the vertical datum.

Z-valuesThe elevations of the 3-D surface above the vertical datum at designated X/Y locations

Standard deviation

µMean error or bias

ω,φ,κSystem defining angular orientation in space, also called the roll, pitch and yaw of an aircraft or sensor, in which ω (roll) is the rotation about the x-axis (the direction of flight), φ (pitch) is the rotation about the y-axis, and κ (yaw) is the rotation about the vertical z-axis. These three angles are obtained directly from Inertial Measurement Unit (IMU) measurements or indirectly from aerial triangulation to identify the angular orientation of a sensor at the instant an aerial photo or image is taken, or the instant when a LiDAR or IFSAR pulse is emitted; these angles provide half of the six exterior orientation parameters used for mapping by photogrammetry, lidargrammetry or radargrammetry. See also x,y,z.

B-2.Abbreviations

ABGPSAirborne GPS

ABSAcoustic Backscatter

ACSMAmerican Congress on Surveying and Mapping

AGCArmy Geospatial Center

AGLAbove Ground Level

AINSAided Inertial Navigation System

ALBAirborne Lidar Bathymetry

ALHAirborne Lidar Hydrography

ALSAirborne Laser Scanning

ALTMAirborne Laser Terrain Mapper (or Mapping)

AMAmplitude Modulation

AMTAbove Mean Terrain

AOIArea Of Interest

AORArea Of Responsibility

ASCIIAmerican Standard Code for Information Interchange

ASFPMAssociation of State Floodplain Managers

ASLAbove Sea Level

ASPRSAmerican Society for Photogrammetry and Remote Sensing

ATCAir Traffic Control

BATSBathymetric And Topographic Survey

BFEBase Flood Elevation

BILBand Interleaved by Line (File Format)

BINBinary

BIPBand Interleaved by Pixel (File Format)

BMPBest Management Practice

BSQBand Sequential (File Format)

C3ICommunications, Command, Control, and Intelligence

C/ACoarse/Acquisition

CADComputer-Aided Design

CADDComputer-Aided Design and Drafting

CAESComputer-Aided Earthmoving System

CCCLCoastal Construction Control Line

CCDCharge Coupled Device

CECircular Error

CEPCircular Error Probable

CIContour Interval

CLICKCenter for Lidar Information, Coordination, and Knowledge

CMASCircular Map Accuracy Standard

CONUSConterminous United States

CORPSCONCorps Conversion

CORSContinuously Operating Reference Station

COTSCommercial Off-the-Shelf

CRSCoordinate Reference System

CVAConsolidated Vertical Accuracy

DEDDigital Elevation Data

DEMDigital Elevation Model

DFIRMDigital Flood Insurance Rate Map

DGDirect Georeferencing

DGNMicroStation Design (File Format)

DGPSDifferential GPS

DoDDepartment of Defense

DOQDigital Orthophoto Quad

DOQQDigital Orthophoto Quarter-Quad

DPIDots per Inch

DRGDigital Raster Graphic

DSMDigital Surface Model

DTEDDigital Terrain Elevation Data

DTMDigital Terrain Model

DVDDigital Video Disk

DWGAutoCAD Drawing (File Format)

DXFDrawing Exchange (File Format)

E00ArcInfo Export (File Format)

EGMEarth Gravitational Model

ENCElectronic Nautical Chart

EPAEnvironmental Protection Agency

ERDCU.S. Army Engineer Research and Development Center

ESRIEnvironmental Systems Research Institute

FAAFederal Aviation Administration

FARFederal Acquisition Regulation

FDCFrequency-to-Distance Conversion

FEMAFederal Emergency Management Agency

FGCCFederal Geodetic Control Committee

FGCSFederal Geodetic Control Subcommittee

FGDCFederal Geographic Data Committee

FIRMFlood Insurance Rate Map

FMFrequency Modulation

FMSFlight Management System

FOGFiber Optic Gyro

FOVField of View

FTPFile Transfer Protocol

FVAFundamental Vertical Accuracy

FWDFull Waveform Digitizing

FWHMFull Width at Half Maximum

GBGigabyte

GDOPGeometric Dilution of Position

GeoTIFFGeoreferenced Tagged Image File Format

GHzGigahertz

GISGeographic Information System

GLONASSGlobal Navigation Satellite System

GMTGreenwich Mean Time

GNSSGlobal Navigation Satellite System

GOTSGovernment Off-the-Shelf

GPRAGovernment Performance and Results Act

GPSGlobal Positioning System

GSDGround Sample Distance

HARNHigh Accuracy Reference Network

H&HHydrologic and Hydraulic

IDIdentification

IFOVInstantaneous Field of View

IFSARInterferometric Synthetic Aperture Radar (also InSAR)

IGLDInternational Great Lakes Datum

IHOInternational Hydrographic Organization

IMGERDAS Image (file format)

IMUInertial Measurement Unit (also IRU)

INSInertial Navigation System (also INU)

InSARInterferometric Synthetic Aperture Radar (also IFSAR)

INUInertial Navigation Unit (also INS)

IONInstitute of Navigation

IPPInterpulse Period

IRInfrared

IRUInertial Reference Unit (also IMU)

ISOInternational Standards Organization

ITRFInternational Earth Rotation Service Terrestrial Reference Frame

IV & VIndependent Validation and Verification

JALBTCXJoint Airborne Lidar Bathymetry Technical Center of Expertise

JPLJet Propulsion Laboratory

JPSD-POJoint Precision Strike Demonstration Project Office

KARKinematic Ambiguity Resolution (also see OTF)

KGPSKinematic GPS

KHzKilohertz

KWKilowatts

L1Level 1 frequency of GPS satellites

L2Level 2 frequency of GPS satellites

L3Level 3 frequency of GPS satellites

L5Level 5 frequency of Block IIF GPS satellites

LAASLocal Area Augmentation System

LADARLAser Detection And Ranging

LAGLowest Adjacent Grade

LASLASer (File Format)

LASERLight Amplification by Stimulated Emission of Radiation

LCDLiquid Crystal Display

LFELowest Floor Elevation

LiDARLight Detection And Ranging

LISLand Information System

LMSLLocal Mean Sea Level

MASERMicrowave Amplification by Stimulated Emission of Radiation

MBMegabytes

MHHWMean Higher High Water

MHWMean High Water

MHzMegahertz

MIF/MIDMapInfo File (format)

MLLWMean Lower Low Water

MLWMean Low Water

MSEMean of the Squared Errors

MSLMean Sea Level

MTLMean Tide Level

NAD 27North American Datum of 1927 (horizontal datum)

NAD 83North American Datum of 1983 (horizontal datum)

NADCONNorth American Datum Conversion

NAVD 88North American Vertical Datum of 1988

NAVSTARNavigation Signal Timing and Ranging

NDEPNational Digital Elevation Program

NDGPSNationwide Differential GPS

NDOPNational Digital Orthophoto Program

NEDNational Elevation Dataset

NEOSNational Earth Orientation Service

NFIPNational Flood Insurance Program

NGANational Geospatial-Intelligence Agency

NGPNational Geospatial Program

NGSNational Geodetic Survey

NGVD 29National Geodetic Vertical Datum of 1929

NIRNear Infra-red

NMASNational Map Accuracy Standard

NOAANational Oceanic and Atmospheric Administration

NOSNational Ocean Service

NPSNominal Pulse Spacing

NRCSNatural Resources Conservation Service

NSDINational Spatial Data Infrastructure

NSGICNational States Geographic Information Council

NSRSNational Spatial Reference System

NSSDANational Standard for Spatial Data Accuracy

NTDENational Tidal Datum Epoch

NTMNational Technical Means

NVANon-Vegetated Vertical Accuracy

NWLONNational Water Level Observation Network

O&MOperations and Maintenance

OCOrder/Class Code

OCONUSOutside the Conterminous United States

OGCOpen GIS Consortium

OIMOrthorectified Image Mosaic

OTFOn-the-fly (GPS ambiguity resolution)

OTSOff-the-shelf

PDOPPosition Dilution of Position

PODPrint on Demand

POSPosition and Orientation System

POS/AVPosition and Orientation System for Airborne Vehicles

POS/LVPosition and Orientation System for Land Vehicles

POS/MVPosition and Orientation System for Marine Vessels

PPMParts Per Million

PPPPrecise Point Positioning

PRFPulse Repetition Frequency

PRRPulse Repetition Rate

PSPPseudo Stereo Pair

QAQuality Assurance

QA/QCQuality Assurance/Quality Control

QCQuality Control

QL1Quality Level 1

QL2Quality Level 2

QL3Quality Level 3

QL4Quality Level 4

QL5Quality Level 5

R&DResearch & Development

RMS Root-Mean-Square

RMSERoot-Mean-Square-Difference

RMSERoot-Mean-Square Error

RMSErRadial RMSE (horizontal, as function of RMSEx and RMSEy)

RMSExRMSE in the x dimension (Easting or longitude)

RMSEyRMSE in the y dimension (Northing or latitude)

RMSEzRMSE in the z dimension (Elevation)

RTKReal Time Kinematic

RTKGPSReal Time Kinematic Global Positioning System

SASelective Availability

SARSynthetic Aperture Radar

SDTSSpatial Data Transfer Standard

SFHASpecial Flood Hazard Area

SGMSemi-Global Matching

SHOALSScanning Hydrographic Operational Airborne Lidar Survey

SHPArcView Shape (File Format)

SONARSound Navigation and Ranging

SPCSState Plane Coordinate System

SVASupplemental Vertical Accuracy

TDOPTime Dilution of Position

TEC (U.S. Army) Topographic Engineering Center

TEC Total Electron Count

TIFFTagged Image File Format

TINTriangulated Irregular Network

TOFTime-of-Flight

TPETotal Propagated Error

UASUnmanned Aerial System

UAVUnmanned Aerial Vehicle

USACEU.S. Army Corps of Engineers

USCGU.S. Coast Guard

USFSU.S. Forest Service

USGSU.S. Geological Survey

UTCUniversal Time, Coordinated, the same as Greenwich Mean Time

UTMUniversal Transverse Mercator

UVUltraviolet

VERTCONVertical Conversion

VHFVery High Frequency

VLBIVery Long Baseline Interferometry

VMASVertical Map Accuracy Standard

VPFVector Product Format

VRSVirtual Reference Station

VVAVegetated Vertical Accuracy

WAASWide Area Augmentation System

WGS 84World Geodetic System of 1984

XMLeXtensible Markup Language

2-DTwo Dimensional

3-DThree Dimensional

3DEP3-D Elevation Program

B-3.Definitions

A

Accelerometer — A device that measures the total specific force with respect to an inertial reference comprising gravity plus acceleration.

Acoustic Wave — See Sound Wave.

Accuracy — The closeness of an estimated value (e.g., measured or computed) to a standard or accepted (true) value of a particular quantity. Note: With the exception of Continuously Operating Reference Stations (CORS), assumed to be known with zero errors relative to established datums, the true locations of 3-D spatial coordinates of other points are not known, but only estimated. Therefore, the accuracy of other coordinate information is unknown and can only be estimated.

• Absolute Accuracy—A measure that accounts for all systematic and random errors in a data set. Absolute accuracy is stated with respect to a defined datum or reference system. For consistency with the NSSDA, absolute accuracy is normally expressed at the 95 percent confidence level. The absolute vertical accuracy is normally different from the absolute horizontal accuracy.

• Accuracyr — The NSSDA reporting standard in the horizontal component that equals the radius of a circle of uncertainty, such that the true or theoretical horizontal location of the point falls within that circle 95-percent of the time. Accuracyr = 1.7308 x RMSEr.
• Accuracyz — The NSSDA reporting standard in the vertical component that equals the linear uncertainty value, such that the true or theoretical vertical location of the point falls within that linear uncertainty value 95-percent of the time. Accuracyz = 1.9600 x RMSEz.

• Horizontal Accuracy — The positional accuracy of a dataset with respect to a horizontal datum. The horizontal accuracy reporting standard (Accuracyr) is defined above.
• Local Accuracy — A value that represents the uncertainty in the coordinates of a control point relative to the coordinates of other directly-connected, adjacent control points, normally expressed at the 95-percent confidence level. The reported local accuracy is an approximate average of the individual local accuracy values between this control point and other observed control points used to establish the coordinates of the control point.
• Network Accuracy — A value that represents the uncertainty in the coordinates of a control point with respect to the geodetic datum at the 95-percent confidence level. For National Spatial Reference System (NSRS) network accuracy classification in the U.S., the datum is considered to be best expressed by the geodetic values at the CORS supported by the National Geodetic Survey (NGS). By this definition, the local and network accuracy values at CORS sites are considered to be infinitesimal, i.e., to approach zero.
• Positional Accuracy — The accuracy of the position of features, including horizontal and/or vertical positions.
• Relative Accuracy — A measure that accounts for random errors in a data set. Relative accuracy may also be referred to as point-to-point accuracy. The general measure of relative accuracy is an evaluation of the random errors (systematic errors and blunders removed) in determining the positional orientation (e.g., distance, azimuth) of one point or feature with respect to another. In lidar, this may also specifically mean the accuracy between adjacent swaths within a lift, adjacent lifts within a project, or between adjacent projects.
• Vertical Accuracy — The measure of the positional accuracy of a dataset with respect to a specified vertical datum. The vertical accuracy reporting standard (Accuracyz) is defined above.

Adjustment — A process designed to minimize inconsistencies in measured or computed quantities by applying derived corrections to compensate for random or accidental errors. The most common interpretation is that the sum of the squares of differences between results obtained by measurement and results obtained by calculation shall be a minimum. With this criterion, the method of least squares adjustment is preferred.

Aerial Triangulation (Aerotriangulation) — The process of measuring a number of points on overlapping images and/or ground control points to determine the most probable values of exterior orientation elements of aerial photographs. The output of this process includes ground space coordinates for all points measured on at least two images.

Affine Transformation — Linear transformation plus a translation. Affine transformation can be decomposed into rotational, scale, skew and translation components and for most sensors small errors are well modeled by these terms.

Air Base — The line segment, or length of the line segment, joining two adjacent camera stations when aerial photographs or images are taken.

Airborne GPS —A method for collecting Global Positioning System (GPS) data continuously for an aerial camera, LiDAR or IFSAR sensor so as to:(1) provide Direct Georeferencing of photo centers and/or the origin of individual laser or radar pulses used in mapping, (2) strengthen the positioning accuracy whiledrastically reducing the number of ground control points necessary on larger mapping projects, and/or (3) enable accurate execution of pre-planned flight lines in automated Flight Management Systems. For example, a geodetic quality GPS receiver records an event marker from the aerial mapping camera,logging the precise time of each exposure station or photo center; this time record is then correlated to the location of GPS ground stations (at known, surveyed locations) which were also recording during the flight.

Aliasing — The difference between the values of constants in a mathematical model and the value the constants would have if the model were improved by adding more terms or denser data.

Altimetry — The science of measuring height or altitudes of different objects.

Ambiguity Resolution — Combining the phase data from two or more GPS receivers so that, after eliminating all other significant errors, the unknown number of integer wavelengths can be determined for signals coming from GPS satellites. Redundant L1 and L2 phase observations from two or more receivers, each tracking five or more satellites, provide the information for rapid unambiguous resolution. Once the ambiguities are resolved, the corrected phases for each observed satellite become precise ranges that allow the computation of the baseline vector(s) between the receivers with a typical accuracy of 2-10 centimeters.

Analog Photogrammetry — Stereo photogrammetric procedures that utilize direct viewing of film imagery in analog stereoplotters that optically and/or mechanically replicate, at reduced scale, the physical geometry that existed when stereo photography was acquired. Analog stereoplotters are less accurate than analytical stereoplotters, and they are ill-suited for DEM production.

Analytical Photogrammetry — Stereo photogrammetric procedures that utilize direct viewing of film imagery in analytical stereoplotters that mathematically replicate, at reduced scale, the physical geometry that existed when stereo photography was acquired. Analytical stereoplotters can also mathematically apply camera calibration (interior orientation) parameters, and correct for atmospheric refraction and earth curvature.

Antivignetting Filter — A filter used with wide-angle photography to produce uniform lighting over the whole photograph.

Arc Second (Arc-Second or Second of Arc) — In angular measurements, 1/3600th of a degree. Commonly used in descriptions of geographic coordinate reference systems, for example, the horizontal resolution of the National Elevation Dataset (NED), 1 arc-second, 1/3 arc-second, 1/9 arc-second. For most of the Contiguous United States, 1 arc-second is approximately 30 meters, linear.

Artifacts — An inaccurate observation, effect or result, especially one resulting from the technology used in scientific investigation or from experimental error. In bare-earth elevation models, detectable surface remnants of buildings, trees, towers, telephone poles or other elevated features; also, detectable artificial anomalies that are introduced to a surface model by way of system specific collection or processing techniques, e.g., corn-row effects of profile collection, star and ramp effects from multidirectional contour interpolation, or detectable triangular facets caused when vegetation canopies are weeded from lidar data. Orthophotos and other geospatial datasets also have blemishes referred to as artifacts.