Digital Elevation Model for Atlantic City, New Jersey:

Procedures, Data Sources and Analysis

Prepared for the Pacific Marine Environmental Laboratory (PMEL) NOAA Center for 

Tsunami Research by the NOAA National Geophysical Data Center (NGDC)

October 11, 2007

Taylor, L.A., B.W. Eakins, K.S. Carignan, R.R. Warnken, T. Sazonova, and D.C. Schoolcraft

NOAA, National Geophysical Data Center, Boulder, Colorado

Corresponding author contact:

Lisa A. Taylor

NOAA, National Geophysical Data Center

Marine Geology and Geophysics Division

325 Broadway, E/GC 3

Boulder, Colorado 80305

Phone: 303-497-6767

Fax: 303-497-6513

E-mail: Lisa.A.Taylor@noaa.gov

http://www.ngdc.noaa.gov/mgg/inundation/
2 DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY

CONTENTS

1. Introduction ............................................................................................................................................. 4

2. Study Area............................................................................................................................................... 5

3. Methodology ........................................................................................................................................... 5

3.1 Data Sources and Processing.......................................................................................................... 6

3.1.1 Shoreline.................................................................................................................... 7

3.1.2 Bathymetry................................................................................................................ 9

3.1.3 Topography ............................................................................................................. 19

3.1.4 Bathymetric–Topography....................................................................................... 21

3.2 Establishing Common Datums..................................................................................................... 23

3.2.1 Vertical datum transformations ............................................................................. 23

3.2.2 Horizontal datum transformations......................................................................... 23

3.3 Digital Elevation Model Development........................................................................................ 24

3.3.1 Verifying consistency between datasets................................................................ 24

3.3.2 Pre-surfacing of USACE bathymetric dataset ...................................................... 24

3.3.3 Smoothing of bathymetric data.............................................................................. 25

3.3.4 Gridding the data with MB-System....................................................................... 25

3.4 Quality Assessment of the DEM.................................................................................................. 26

3.4.1 Horizontal accuracy................................................................................................ 26

3.4.2 Vertical accuracy .................................................................................................... 26

3.4.3 Slope maps and 3-D perspectives.......................................................................... 27

3.4.4 Comparison with source data files......................................................................... 28

3.4.5 Comparison with NGS geodetic monuments........................................................ 29

4. Summary and Conclusions................................................................................................................... 30

5. Acknowledgments ................................................................................................................................ 30

6. References............................................................................................................................................. 30

7. Data Processing Software..................................................................................................................... 31

LIST OF FIGURES

Figure 1. Shaded-relief image of the Atlantic City, New Jersey DEM ....................................................... 4

Figure 2. Geologic regions of New Jersey..................................................................................................... 5

Figure 3. Source and coverage of datasets used to compile the Atlantic City DEM.................................. 6

Figure 4. Digital coastline datasets available in the Atlantic City region.................................................... 7

Figure 5. Aerial photo of Atlantic City at Absecon Inlet entrance .............................................................. 8

Figure 6. Spatial coverage of bathymetric datasets used to compile the Atlantic City

DEM ....................................................................................................................................... 10

Figure 7. Digital NOS hydrographic survey coverage in the Atlantic City region................................... 14

Figure 8. Digital USACE hydrographic survey coverage in the Atlantic City region ............................. 16

Figure 9. Spatial coverage of NOS shallow-water multibeam sonar surveys used to 

compile the Atlantic City DEM............................................................................................ 17

Figure 10. Spatial coverage of ENC sounding data and NGDC digitized ICW segments......................... 18

Figure 11. Illustration of CRSSA research on submerged aquatic vegetation ............................................ 20

Figure 12. The 1/3 arc-second Atlantic City DEM and USGS quad sheets at Townsend Inlet................. 20

Figure 13. Spatial coverage of CSC/JALBTCX bathymetric–topographic LiDAR

dataset used to compile the Atlantic City DEM .................................................................. 21

Figure 14. Spatial coverage of CSC VDatum transformation tool .............................................................. 23

Figure 15. Gridding artifacts in preliminary DEM ...................................................................................... 24

Figure 16. Histogram of the differences between NOS hydrographic survey H09552 and the 1 

arc-second pre-surfaced bathymetric grid ............................................................................ 25

Figure 17. Slope map of the Atlantic City DEM........................................................................................... 27

Figure 18. Perspective view from the southeast of the Atlantic City DEM ................................................ 28

Figure 19. Histogram of the differences between one CSC/JALBTCX survey and the 

Atlantic City DEM................................................................................................................. 28
DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY 3

Figure 20. Histogram of the differences between NGS geodetic monument elevations 

and the Atlantic City DEM ................................................................................................... 29

Figure 21. Location of NGS geodetic monuments and the NOAA Atlantic City tide 

station ..................................................................................................................................... 29

LIST OF TABLES

Table 1. PMEL specifications for the Atlantic City, New Jersey DEM..................................................... 5

Table 2. Shoreline datasets available in the Atlantic City, New Jersey region.......................................... 7

Table 3. Electronic navigational charts available in the Atlantic City, New Jersey region ...................... 8

Table 4. Bathymetric datasets used in compiling the Atlantic City DEM ................................................. 9

Table 5. Digital NOS hydrographic surveys used in compiling the Atlantic City DEM........................ 11

Table 6. USACE surveys used in compiling the Atlantic City DEM....................................................... 15

Table 7. NOS shallow water multibeam surveys used in compiling the Atlantic City DEM................. 17

Table 8. Topographic datasets used in compiling the Atlantic City DEM............................................... 19

Table 9. Bathymetric–topographic dataset used in compiling the Atlantic City DEM........................... 21

Table 10. Relationship between Mean High Water and other vertical datums in the

Atlantic City region ............................................................................................................... 23

Table 11. Data hierarchy used to assign gridding weight in MB-System.................................................. 25
4 DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY

Digital Elevation Model for Atlantic City, New Jersey:

Procedures, Data Sources and Analysis

1. INTRODUCTION

The National Geophysical Data Center (NGDC), an office of the National Oceanic and Atmospheric 

Administration (NOAA), has developed a bathymetric–topographic digital elevation model (DEM) of 

Atlantic City, New Jersey (Fig. 1) for the Pacific Marine Environmental Laboratory (PMEL) NOAA Center 

for Tsunami Research (http://nctr.pmel.noaa.gov/). The 1/3 arc-second1 coastal DEM will be used as input 

for the Method of Splitting Tsunami (MOST) model developed by PMEL to simulate tsunami generation, 

propagation and inundation. The DEM was generated from diverse digital datasets in the region (grid 

boundary and sources shown in Fig. 3) and will be used for tsunami inundation modeling, as part of the 

tsunami forecast system SIFT (Short-term Inundation Forecasting for Tsunamis) currently being developed 

by PMEL for the NOAA Tsunami Warning Centers. This report provides a summary of the data sources 

and methodology used in developing the Atlantic City DEM.

Figure 1. Shaded-relief image of the Atlantic City, New Jersey DEM. Contour interval is 100 meters.

 1. The Atlantic City DEM is built upon a grid of cells that are square in geographic coordinates (latitude and longitude), however, the 

cells are not square when converted to projected coordinate systems, such as UTM zones (in meters). At the latitude of Atlantic City, 

New Jersey (39°21.828′ N, 74°25.099′ W) 1/3 arc-second of latitude is equivalent to 10.28 meters; 1/3 arc-second of longitude equals 

7.98 meters.
DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY 5

2. STUDY AREA

The Atlantic City DEM covers the coastal region surrounding the town of Atlantic City, New Jersey

from Cape May in the south to Barnegat Light in the north and includes the communities of Wildwood, 

Avalon, Sea Isle City, Ocean City, Brigantine, Beach Haven, and Harvey Cedars (Fig. 1).

Many of the rural communities surround Delaware Bay while the rapidly growing suburban and 

developing urban populations are along the Atlantic coast. New Jersey’s coastal economy is based not only

on tourism but also on commercial and recreational fishing. The Outer Coastal Plain supports the economy 

by providing habitat to wildlife, migratory birds, and marine life. The estuaries and salt marshes in this 

region were formed by the gradual infill of mud and sand from the rivers while the barrier islands to the 

east act to protect these wetlands. Coastal processes such as wave action and along shore currents 

continually shape and modify the New Jersey coastline.

Figure 2. Geologic regions of New Jersey. The 

Atlantic City DEM boundary shown in red. 

(http://njaes.rutgers.edu/njriparianforestbuffers/nat

iveALL.htm).

3. METHODOLOGY

The Atlantic City, New Jersey DEM was developed to meet PMEL specifications (Table 1), based on 

input requirements for the MOST inundation model. The best available digital data were obtained by 

NGDC and shifted to common horizontal and vertical datums: World Geodetic System 1984 (WGS84) and 

Mean High Water (MHW), for modeling of “worst-case scenario” flooding, respectively. Data processing 

and evaluation, and DEM assembly and assessment are described in the following subsections.

Table 1: PMEL specifications for the Atlantic City, New Jersey DEM.

Grid Area Atlantic City, New Jersey

Coverage Area 74.00o to 75.05o W; 38.85o to 39.75o N

Coordinate System Geographic decimal degrees

Horizontal Datum World Geodetic System 1984 (WGS84)

Vertical Datum Mean High Water (MHW)

Vertical Units Meters

Grid Spacing 1/3 arc-second

Grid Format ESRI Arc ASCII grid
6 DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY

3.1 Data Sources and Processing

Shoreline, bathymetric, topographic, and bathymetric–topographic digital datasets (Fig. 3) were 

obtained from several U.S. federal, state and local agencies including: NOAA’s National Ocean Service 

(NOS), Office of Coast Survey (OCS) and Coastal Services Center (CSC); the Joint Airborne LiDAR 

Bathymetry Technical Center of Expertise (JALBTCX); the U.S. Geological Survey (USGS); and the U.S. 

Army Corps of Engineers (USACE). Safe Software’s (http://www.safe.com/) FME data translation tool 

package was used to shift datasets to WGS84 horizontal datum and to convert them into ESRI 

(http://www.esri.com/) ArcGIS shape files. The shape files were then displayed with ArcGIS to assess data 

quality and manually edit datasets. Vertical datum transformations to MHW were accomplished using 

FME, based upon data from the NOAA Atlantic City tide station and NOAA's Office of Coast Survey and 

National Geodetic Survey VDatum model software (http://nauticalcharts.noaa.gov/csdl/vdatum.htm).

Applied Imagery’s Quick Terrain Modeler software (http://www.appliedimagery.com/) was used to edit 

and assess the quality of the LiDAR data as well as evaluate processing and gridding techniques.

Figure 3. Source and coverage of datasets used to compile the Atlantic City DEM.
DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY 7

3.1.1 Shoreline

Coastline datasets of the Atlantic City region were obtained from NOAA’s Office of Coast Survey,

Coastal Services Center (CSC); the New Jersey Department of Environmental Protection (NJDEP); and 

Center for Remote Sensing and Spatial Analysis (CRSSA) at Rutgers University. Analysis of the NJDEP 

and Rutgers coastlines showed both to be less detailed than coastlines extracted from the ENCs and

therefore were not used in building the Atlantic City DEM. NGDC created a partial shoreline from CSC 

coastal LiDAR data that was used in combination with the ENCs to build a ‘combined coastline’ for the 

Atlantic City region (Table 2; Fig. 4).

Table 2: Shoreline datasets used in the Atlantic City DEM.

Source Year Data Type

Spatial 

Resolution

Original Horizontal 

Datum/Coordinate 

System

Original Vertical 

Datum URL

OCS ENCs 2006-

2007 Coastline 1:80,000 to 1:400,000 WGS84 geographic Mean High Water

http://nauticalchar

ts.noaa.gov/mcd/e

nc/index.htm

NGDC/CSC 

LiDAR derived 

shoreline

Contour WGS84 geographic Mean High Water

Figure 4. Digital coastline datasets available in the Atlantic City region.
8 DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY

1) OCS electronic navigational chart

Four electronic navigational charts (ENCs) were available for the Atlantic City area (Table 3)

and were downloaded from NOAA’s Office of Coast Survey website 

(http://nauticalcharts.noaa.gov/mcd/enc/index.htm). The ENCs are available in S-57 format and 

include coastline data files referenced to Mean High Water. Other nautical charts are available as 

georeferenced raster nautical charts (RNCs; digital images of the charts) and were used to QC 

bathymetric, bathymetric–topographic, and topographic datasets.

2) NGDC/Coastal Services Center LiDAR derived contour shoreline

In order to define the current coastline, NGDC processed the most recent high-resolution 

bathymetric–topographic LiDAR dataset along the coast that was available from CSC to create a 

zero-elevation coastline at Mean High Water vertical datum. The zero contour line incorporated

some jetties and coastal land features not present in the ENC coastlines.

Table 3: Electronic navigational charts available in the Atlantic City, New Jersey region.

Chart Title Edition Year of Source data Issue Date Scale

12300 Approaches to New York Nantucket Shoals to 

Five Fathom Bank 12 2003 2007-07-26 1:400,000

12214 Cape May to Fenwick Island 9 1999 to 2004 2007-06-25 1:80,000

12304 Delaware Bay 8 1999 to 2004 2007-08-01 1:80,000

12318 Little Egg Inlet to Hereford Inlet 1 2005 2007-07-26 1:80,000

The ENC coastlines were merged with the derived contour coastline to create a ‘combined coastline’ 

for the Atlantic City region. Channel inlets were included in the ‘combined coastline’ where digital 

bathymetric data were present. Modifications to the coastline include adjustments to fit the most recent 

bathymetric–topographic data. In addition, piers, docks, and bridges like those shown in Figure 5 were 

removed. All modifications were done using ArcMap editing tools.

Figure 5. Aerial photo of Atlantic City at Absecon Inlet.
DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY 9

3.1.2 Bathymetry

Bathymetric datasets used in the compilation of the Atlantic City DEM include 65 NOS hydrographic 

surveys, eight USACE surveys located within harbors and inlets, three NOS shallow-water multibeam

sonar surveys that cover the near shore area, an NGDC digitized representation of the Intracoastal 

Waterway, and extracted ENC sounding data (Table 4; Fig. 6).

Table 4: Bathymetric datasets used in compiling the Atlantic City DEM.

Source Year Data Type Spatial Resolution

Original 

Horizontal 

Datum/Coordinate 

System

Original 

Vertical 

Datum

URL

 NOS 1935 to 

2002

Hydrographic 

survey 

soundings

Ranges from 10 m to 

1 km (varies with 

scale of survey, 

depth, traffic, and 

probability of 

obstructions)

NAD27 or NAD83

geographic

Mean Low 

Water or 

Mean Lower 

Low Water

http://www.ngdc.noaa.gov

/mgg/bathymetry/hydro.ht

ml

USACE 2006 to 

2007

Hydrographic 

survey 

profiles

Ranges from 150 to 

1500 m line spacing 

150 to 300 m apart 

with 2 to 5 m point 

spacing

NAD83 New 

Jersey State Plane

(feet)

NAVD88

(feet)

NOS 2003

Shallow water 

multibeam

sonar

10 meters NAD83

geographic

Mean Lower 

Low Water

http://www.ngdc.noaa.gov

/mgg/bathymetry/hydro.ht

ml

NGDC -

ICW

digitized 

soundings ~ 10 meters WGS84 geographic

Mean High 

Water

OCS 

ENC

2006 to 

2007

Extracted 

soundings 1:80,000 to 1:400,000 WGS84 geographic

Mean High 

Water

http://nauticalcharts.noaa.g

ov/mcd/enc/index.htm
10 DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY

Figure 6. Spatial coverage of bathymetric datasets used to compile the Atlantic City DEM.
DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY 11

1) NOS hydrographic survey data

A total of 82 NOS hydrographic surveys conducted between 1935 and 2002 were available 

for use in developing the Atlantic City DEM (Table 5; Fig. 7). The hydrographic survey data were 

originally vertically referenced to Mean Lower Low Water (MLLW) or Mean Low Water (MLW) 

and horizontally referenced to either NAD27 or NAD83 datums. Only 65 of the 82 surveys were 

used in building the Atlantic City DEM, as some older surveys have been superseded.

Data point spacing for the NOS surveys varied by collection date. In general, earlier surveys 

had greater point spacing than more recent surveys. All surveys were extracted from NGDC’s 

online NOS hydrographic database (http://www.ngdc.noaa.gov/mgg/bathymetry/hydro.html). The 

data were then converted to WGS84 and MHW using FME software, an integrated collection of 

spatial extract, transform, and load tools for data transformation (http://www.safe.com). The 

surveys were subsequently clipped to a polygon 0.05 degree (~5%) larger than the Atlantic City

DEM area to support data interpolation along grid edges.

After converting all NOS survey data to MHW using VDatum and tide station offset (see 

Section 3.2.1), the data were displayed in ESRI ArcMap and reviewed for digitizing errors against 

scanned original survey smooth sheets and edited as necessary. The surveys were also compared 

to the topographic, bathymetric, and bathymetric–topographic datasets, the combined coastline,

and NOS raster nautical charts (RNCs). The surveys were clipped to remove soundings that 

overlap the more recent multibeam surveys, where the USACE surveys were located within the 

inlets and along the coastline and where soundings from older surveys have been superseded by 

more recent NOS surveys.

Table 5: Digital NOS hydrographic surveys used in compiling the Atlantic City DEM.

Survey ID Year Scale Original Vertical Datum Original Horizontal 

Datum

Vertical Datum 

conversion used

H05893 1935 10,000 mean low water NAD27 Offset and 

VDatum

H05894 1935 10,000 mean low water NAD27 Offset

H06141 1936 10,000 mean low water NAD27 Offset and 

VDatum

H06142 1936 10,000 mean low water NAD27 Offset

H06144 1936 10,000 mean low water NAD27 Offset and 

VDatum

H06188 1936 40,000 mean low water NAD27 Offset and 

VDatum

H06213 1936 10,000 mean low water NAD27 Offset

H06215 1936 10,000 mean low water NAD27 Offset

H06216 1936 10,000 mean low water NAD27 Offset and 

VDatum

H06214 1937 5,000 mean low water NAD27 Offset

H06218 1937 10,000 mean low water NAD27 Offset

H06224 1937 10,000 mean low water NAD27 Offset and 

VDatum

H06230 1937 10,000 mean low water NAD27 Offset and 

VDatum

H06231 1937 10,000 mean low water NAD27 Offset and 

VDatum

H06236 1937 10,000 mean low water NAD27 Offset and 

VDatum

H06254 1937 10,000 mean low water NAD27 Offset
12 DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY

H06262 1937 10,000 mean low water NAD27 Offset and 

VDatum

H06271 1937 40,000 mean low water NAD27 VDatum

H06345 1938 80,000 mean low water NAD27 Offset

H06225 1939 20,000 mean low water NAD27 Offset and 

VDatum

H06226 1940 20,000 mean low water NAD27 Offset and 

VDatum

H06227 1940 20,000 mean low water NAD27 Offset and 

VDatum

H08219 1954 10,000 mean low water NAD27 Offset and 

VDatum

H08220 1954 10,000 mean low water NAD27 Offset and 

VDatum

H08221 1954 10,000 mean low water NAD27 Offset and 

VDatum

H08222 1954 20,000 mean low water NAD27 VDatum

H08672 1962 10,000 mean low water NAD27 Offset and 

VDatum

H08674 1962 10,000 mean low water NAD27 Offset and 

VDatum

H08675 1962 10,000 mean low water NAD27 Offset and 

VDatum

H08676 1962 10,000 mean low water NAD27 Offset and 

VDatum

H09153 1970/71 20,000 mean low water NAD27 Offset and 

VDatum

H09154 1970 10,000 mean low water NAD27 Offset

H09203 1971 10,000 mean low water NAD27 Offset

H09204 1971 5,000 mean low water NAD27 Offset

H09241 1971 20,000 mean low water NAD27 Offset

H09310 1972 5,000 mean low water NAD27 Offset and 

VDatum

H09311 1972 10,000 mean low water NAD27 Offset and 

VDatum

H09312 1972 20,000 mean low water NAD27 Offset and 

VDatum

H09533 1975 20,000 mean low water NAD27 Offset

H09534 1975 40,000 mean low water NAD27 VDatum

H09542 1975 40,000 mean low water NAD27 VDatum

H09552 1975 40,000 mean low water NAD27 VDatum

H09573 1975 40,000 mean low water NAD27 VDatum

H09622 1976 40,000 mean low water NAD27 Offset and 

VDatum

H09699 1977 20,000 mean low water NAD27 Offset and 

VDatum
DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY 13

H09700 1977 20,000 mean low water NAD27 Offset

H09722 1977 5,000 mean low water NAD27 Offset

H09723 1977 20,000 mean low water NAD27 Offset

H10167 1984 20,000 mean lower low water NAD27 Offset

H10439 1992 20,000 mean lower low water NAD83 Offset

H10440 1992 20,000 mean lower low water NAD83 Offset

H10444 1992/93 20,000 mean lower low water NAD83 Offset

H10446 1992/93 20,000 mean lower low water NAD83 Offset

H10489 1993 20,000 mean lower low water NAD83 Offset

H10234 1994 10,000 mean lower low water NAD83 Offset

H10241 1994 10,000 mean lower low water NAD83 Offset

H10573 1994 10,000 mean lower low water NAD83 Offset

F00453 1999 10,000 mean lower low water NAD83 Offset

H10917 1999 10,000 mean lower low water NAD83 Offset

H10935 1999 20,000 mean lower low water NAD83 Offset and 

VDatum

H10936 1999 20,000 mean lower low water NAD83 Offset

H10926 1999/2000 10,000 mean lower low water NAD83 Offset

H11081 2001/02 20,000 mean lower low water NAD83 Offset

H11104 2002 20,000 mean lower low water NAD83 Offset and 

VDatum

H11241 2004 20,000 mean lower low water NAD83 UTM zone 18 

North VDatum
14 DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY

Figure 7. Digital NOS hydrographic survey coverage in the Atlantic City region. Some older surveys were not 

used as they have been superseded by more recent surveys. DEM boundary in brown.
DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY 15

2) U.S. Army Corps of Engineers hydrographic surveys

The USACE, Philadelphia District provided NGDC with eight bathymetric surveys located 

along the New Jersey coastline and within inlets (Table 6, Fig. 8). The surveys were collected in 

2006 and 2007, and referenced to NAD83 New Jersey State Plane (feet) and NAVD88 (feet)

datums. The files were converted to WGS84 and MHW using FME. Point spacing averages less 

than 2 meters along profiles 1500 to 1700 meters long and averaging 300 meters apart. Inlet 

surveys are several thousand meter square grids formed by intersecting survey lines with point 

spacing of less than 5 meters.

Beach profiles and inlet surveys were evaluated using Arc Map and surfaced with GMT (see 

section 3.3.2) to eliminate ridges and a “waffle” pattern.

Table 6: USACE surveys used in compiling the Atlantic City DEM.

Region Year of Survey Survey Scale Original Vertical Datum Original Horizontal 

Datum

Absecon Inlet 2006

2600 x 3600 m grid with <

150 m line spacing and < 5 

m point spacing

NAD83 New Jersey State 

Plane (feet) NAVD88 (feet)

Absecon Island

profiles 2006

beach profiles ~1500 m 

wide, spaced ~300 m apart 

with < 2 m point spacing

NAD83 New Jersey State 

Plane (feet) NAVD88 (feet)

Cape May

profiles 2007

beach profiles ~1500 m 

wide, spaced ~300 m apart 

with < 2 m point spacing

NAD83 New Jersey State 

Plane (feet) NAVD88 (feet)

Great Egg 

Harbor Inlet 2006

4400 x 3800 m grid with 150 

m line spacing and < 5 m 

point spacing

NAD83 New Jersey State 

Plane (feet) NAVD88 (feet)

Avalon profiles 2007

beach profiles ~1500 m 

wide, spaced ~300 m apart 

with < 2 m point spacing

NAD83 New Jersey State 

Plane (feet) NAVD88 (feet)

Brigantine Inlet 2006

2500 x 3500 m grid with <

150 m line spacing and < 5 

m point spacing

NAD83 New Jersey State 

Plane (feet) NAVD88 (feet)

Brigantine Island

profiles 2006

beach profiles ~1500 m 

wide, spaced ~300 m apart 

with < 2 m point spacing

NAD83 New Jersey State 

Plane (feet) NAVD88 (feet)

Ocean City

profiles 2006

beach profiles ~1700 m 

wide, spaced ~300 m apart 

with < 2 m point spacing

NAD83 New Jersey State 

Plane (feet) NAVD88 (feet)
16 DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY

Figure 8. Digital USACE hydrographic survey coverage in the Atlantic City region.
DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY 17

3) NOS shallow water multibeam survey

NOAA’s NOS conducted several shallow water multibeam sonar surveys along the New 

Jersey coast (Table 7, Fig. 9). Three surveys were downloaded from the NGDC hydrographic 

survey website (http://www.ngdc.noaa.gov/mgg/bathymetry/hydro.html) in ASCII xyz gridded 

format in NAD83 geographic at 10-meter resolution and referenced to MLLW. This dataset 

provided dense bathymetric coverage in the area.

Table 7: Digital NOS shallow water multibeam surveys used in compiling the Atlantic City DEM.

NOS Survey ID Year of Survey Survey Scale Original Vertical Datum Original Horizontal Datum

H11197 2003 20,000 mean lower low water NAD83 geographic

H11198 2003 20,000 mean lower low water NAD83 geographic

H11243 2004 40,000 mean lower low water NAD83 geographic

Figure 9. Coverage of NOS shallow-water multibeam sonar surveys. 
18 DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY

4) Office of Coast Survey Electronic navigational chart extracted soundings

The OCS electronic navigational chart sounding data were extracted from charts #12318 and 

#12304 and converted to MHW using FME. NGDC digitized additional soundings from #12304 in 

the Maurice River channel at a depth of -1.82 meters based on Coast Pilot (Fig. 10). By increasing 

the density of soundings in the river channel, the appearance of ‘pits’ in the pre-surfaced 

bathymetric grid was reduced. Soundings from ENC #12318 were clipped to the shallow water

multibeam surveys.

5) Digitized Intracoastal Waterway

NGDC digitized soundings with point spacing of less than one meter for the Intracoastal 

Waterway (ICW; Fig. 10) at a depth of -1.82 meters for the small inland channel north of Sea Isle 

City and -3.66 meters through the Cape May Channel. No other bathymetric data was available. 

Figure 10. Coverage of extracted ENC soundings and the Intracoastal Waterway segments digitized by NGDC.

Some of the inconsistencies were identified while merging the bathymetric datasets due to the range in 

ages of the NOS hydrographic surveys. Coastal erosion and development have modified the coastline 

dramatically to the extent that inlets surveyed in the early 40’s and 50’s have shifted hundreds of meters. In 

areas where more recent data were available, the older surveys were either edited or removed.
DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY 19

3.1.3 Topography

One topographic dataset in the Atlantic City region was obtained and used to build the Atlantic City 

DEM from the U.S. Geological Survey (USGS; Table 8; Fig. 11). NGDC evaluated but did not use the 

Shuttle Radar Topography Mission (SRTM) Elevation 1 arc-second DEM available from USGS.

Table 8: Topographic datasets used in compiling the Atlantic City DEM.

Source Year Data Type Spatial

Resolution

Original Horizontal 

Datum/Coordinate 

System

Original Vertical 

Datum URL

USGS 1999-2000 NED DEM 1/3 arc-second NAD83 geographic NAVD88

(meters) http://ned.usgs.gov/

1) USGS NED topographic DEM

The U.S. Geological Survey (USGS) National Elevation Dataset (NED; http://ned.usgs.gov/) 

provides complete 1/3 arc-second coverage of the Atlantic City region2. Data are in NAD83 

geographic coordinates and NAVD88 vertical datum (meters), and are available for download as

raster DEMs. The bare-earth elevations have a vertical accuracy of +/- 7 to 15 meters depending 

on source data resolution. See the USGS Seamless web site for specific source information 

(http://seamless.usgs.gov/). The dataset was derived from USGS quadrangle maps and aerial 

photographs based on topographic surveys; it has been revised using data collected in 1999 and 

2000. The NED DEM included “zero” elevation values over the open ocean, which were removed 

from the dataset by clipping to the combined coastline.

In marshy areas, the NED topographic data had elevation values below zero. The Absecon 

Wilderness Management Area and the Edwin B. Forsythe National Wildlife Refuge consist of 

roughly 50,000 acres of salt marsh and wetlands. A management technique called “diking” is 

employed to create acres of impounded marsh habitat in the naturally occurring tidal salt marsh.

Water levels are monitored and changed according to wildlife needs and seasons 

(http://www.fws.gov/northeast/forsythe/). The process could result in NED topographic data 

values of less than zero in areas represented as land on nautical charts and topographic maps.

The Grant F. Walton Center for Remote Sensing and Spatial Analysis (CRSSA) at Rutgers 

University also provides research data on the changes in coverage of submerged aquatic 

vegetation in the Barnegat Bay region (Fig. 11).

 2. The USGS National Elevation Dataset (NED) has been developed by merging the highest-resolution, best quality elevation data 

available across the United States into a seamless raster format. NED is the result of the maturation of the USGS effort to provide 

1:24,000-scale Digital Elevation Model (DEM) data for the conterminous U.S. and 1:63,360-scale DEM data for Georgia. The dataset 

provides seamless coverage of the United States, HI, AK, and the island territories. NED has a consistent projection (Geographic), 

resolution (1 arc second), and elevation units (meters). The horizontal datum is NAD83, except for AK, which is NAD27. The vertical 

datum is NAVD88, except for AK, which is NGVD29. NED is a living dataset that is updated bimonthly to incorporate the "best 

available" DEM data. As more 1/3 arc second (10 m) data covers the U.S., then this will also be a seamless dataset. [Extracted from 

USGS NED website]
20 DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY

Figure 11. Map of submerged aquatic vegetation in the Atlantic 

City region. Courtesy of Grant F. Walton Center for Remote 

Sensing and Spatial Analysis (CRSSA) at Rutgers University 

(http://crssa.rutgers.edu/projects/runj/bbdata/index.html).

Two areas of the NED DEM dataset have an offset in elevation values of up to 1 meter. Both are 

located at the seams of the USGS quads, one just west of Townsend Inlet and the other in the Barnegat Bay

area. Figure 12 illustrates the intersection of four quads and the corresponding area in the final 1/3 arcsecond Atlantic City DEM. Other online topographic datasets at similar resolution also contained this offset 

as they use the NED data. The SRTM 1 arc-second DEM did not accurately reflect topography having 

elevations of 6 to 8 meters and was not used.

Figure 12. 1/3 arc-second Atlantic City DEM and quad sheets west of Townsend Inlet. A) The resulting elevation offsets shown as 

difference of light and dark green shades. B) Image of four USGS quad sheets. In both images, the black arrow points to the 

intersection of the quads.
DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY 21

3.1.4 Bathymetry–Topography

Two bathymetric–topographic LiDAR datasets were available from NOAA’s Coastal Services Center

(CSC) Coastal Remote Sensing Program, covering the ocean coastal region of the Atlantic City DEM from 

Cape May to Barnegat Bay. 1996 to 2000 NOAA/USGS/NASA Airborne LiDAR Assessment of Coastal 

Erosion (ALACE) Project for the US Coastline dataset was developed to study coastal changes along the 

New Jersey eastern seaboard. The CSC/JALBTCX 2005 dataset is part of the National Coastal Mapping 

Program to depict the elevations above and below water along the east coastal zone (Fig. 13, Table 9). As 

both datasets provide full coverage of the entire length of the Atlantic Ocean shoreline, only the more 

recent CSC/JALBTCX 2005 dataset was used in building the Atlantic City DEM. Neither dataset was 

processed to bare earth.

Table 9: Bathymetric–topographic dataset used in compiling the Atlantic City DEM.

Source Year Data Type Spatial 

Resolution

Original Horizontal 

Datum/Coordinate System

Original Vertical 

Datum

CSC/JALBTCX 

LiDAR 2005 Coastal LiDAR < 5 meters NAD83 geographic NAVD88 (meters)

Figure 13. Coverage of the CSC/JALBTCX 2005 LiDAR dataset used in building the Atlantic City DEM.
22 DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY

1) CSC/JALBTCX bathymetric–topographic LiDAR 2005

The CSC/JALBTCX LiDAR dataset provided bathymetric–topographic coverage for the 

coastal and near shore regions of the New Jersey coast. These data were obtained in NAD83 

geographic horizontal datum and NAVD88. FME was used to re-project the xyz data to WGS84 

geographic and to MHW. Point spacing varied from less than 5 meters with full coverage at the 

shoreline to greater spacing farther from shore. These data were not processed to bare earth.

In order to simulate a bare earth surface, the LiDAR data was filtered using FME to remove all 

elevations on land over 5 meters. This elevation was used because the majority of the points of high 

elevation located on the shoreline average 15 feet or lower, referencing USGS quad sheets. In areas where 

the quads showed elevation points over 15 feet, those higher elevations were present in the NED 

topographic dataset and so were retained in the final DEM. While not a replacement for bare earth 

processing, the filtering removed the majority of buildings, elevated roadways, and large piers. To further 

edit the data, each data file was reviewed and edited using ArcMap removing docks, bridges, and piers over 

water. Several anomalous returns were found during this QC process and were also removed.
DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY 23

3.2 Establishing Common Datums

3.2.1 Vertical datum transformations

Datasets used in the compilation and evaluation of the Atlantic City DEM were originally referenced

to a number of vertical datums including Mean Lower Low Water (MLLW), Mean Low Water (MLW), 

and North American Vertical Datum of 1988 (NAVD88). All datasets were transformed to MHW to 

provide the worst-case scenario for inundation modeling. Units were converted from feet to meters as 

appropriate.

1) Bathymetric data

The NOS hydrographic surveys, the USACE surveys, and the NOS multibeam sonar survey 

were transformed from MLLW and MLW to MHW, using FME software, by adding a constant 

taken from the Atlantic City tide station #8534720 (Table 10) and by processing using the 

VDatum tool (http://nauticalcharts.noaa.gov/csdl/vdatum.htm ) based on VDatum coverage (Fig. 

14).

Figure 14. Hachured area illustrates coverage of VDatum tool.

2) Topographic data

The USGS NED 1/3 arc-second DEMs were originally referenced to NAVD88. Conversion to 

MHW, using FME software, was accomplished by adding a constant offset of -0.479 meters 

(Table 10) as measured at the Atlantic City tide station.

3) Bathymetric–topographic data

The CSC bathymetric–topographic LiDAR data were transformed from NAVD88 to MHW 

by adding a constant offset of -0.479 meters using FME.

Table 10. Relationship between Mean High Water and other vertical datums at the Atlantic City tide station 

#8534720.

Vertical datum Difference to MHW

NAVD88 -0.479 meters

MLW -1.225 meters

MLLW -1.276 meters

3.2.2 Horizontal datum transformations

Datasets used to compile the Atlantic City DEM were originally referenced to WGS84 geographic, 

NAD83 UTM Zone 18 North, NAD83 New Jersey State Plane, NAD83 geographic, or NAD27 geographic

horizontal datums. The relationships and transformational equations between these horizontal datums are 

well established. All data were converted to a horizontal datum of WGS84 geographic using FME software.
24 DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY

3.3 Digital Elevation Model Development

3.3.1 Verifying consistency between datasets

After horizontal and vertical transformations were applied, the resulting ESRI shape files were checked 

in ArcMap for consistency between datasets. Problems and errors were identified and resolved before 

proceeding with subsequent gridding steps. The evaluated and edited ESRI shape files were then converted 

to xyz files in preparation for gridding. Problems included:

• Suspect topographic elevations located on and within salt marshes and estuaries.

• Inconsistencies within the NED topographic data in two areas. These inconsistencies appear to 

result from merging of digitized USGS quad sheets.

• Data values over the ocean and rivers in the NED topographic data reflecting non-bare earth 

features. The dataset required automated clipping to the combined coastline.

• Bathymetric–topographic LiDAR dataset not processed to bare earth. The dataset required filtering 

of elevation values on land and manual editing of individual features.

• Digital, measured bathymetric values from NOS surveys date back over 70 years. More recent 

data, such as the USACE hydrographic surveys differed from older NOS data by as much as 10 

meters vertically and over 100 meters horizontally. The older NOS survey data were excised 

where more recent bathymetric data exists.

3.3.2 Pre-surfacing of USACE bathymetric dataset

The USACE bathymetric surveys consist of widely spaced beach profiles and soundings with ‘crosshatched’ patterns at inlets. This point distribution required pre-surfacing using GMT to minimize the 

artifacts. Original non-surfaced bathymetric datasets were not used in the final gridding process after test 

grids showed excessive “patchwork” artifacts where datasets merged or overlapped (Fig. 16).

Figure 15. Example of artifacts in test grid at Absecon Inlet. “Waffle” pattern resulted from incorporating non-surfaced USACE 

survey dataset in final gridding. 
DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY 25

3.3.3 Smoothing of bathymetric data

The NOS hydrographic surveys are generally sparse at the resolution of the 1/3 arc-second Atlantic 

City DEM: in both deep water and in some areas close to shore, the NOS survey data have point spacing up 

to 1900 m apart. In order to reduce the effect of artifacts in the form of lines of “pimples” in the DEM due 

to this low resolution dataset, and to provide effective interpolation into the coastal zone, a 1 arc-secondspacing ‘pre-surface’ bathymetric grid was generated using GMT, an NSF-funded share-ware software 

application designed to manipulate data for mapping purposes (http://gmt.soest.hawaii.edu/).

The NOS hydrographic point data, in xyz format, were clipped to remove overlap with the JALBTCX 

bathymetric–topographic LiDAR data, then combined with the surfaced and clipped USACE soundings,

the NOS multibeam data, ENC sounding data, and the digitized ICW segments into a single file, along with 

points extracted from the combined coastline—to provide a buffer along the entire coastline. The coastline 

elevation value was set at -0.5 m to ensure a bathymetric surface below zero in areas where data is sparse or 

non-existent.

The point data were median-averaged using the GMT tool ‘blockmedian’ to create a 1 arc-second grid 

0.05 degrees (~5%) larger than the Atlantic City DEM gridding region. The GMT tool ‘surface’ was then 

used to apply a tight spline tension to interpolate elevations for cells without data values. The GMT grid 

created by ‘surface’ was converted into an ESRI Arc ASCII grid file, and clipped to the combined coastline 

(to eliminate data interpolation into land areas). The resulting surface was compared with original 

soundings to ensure grid accuracy (e.g., Fig. 15), converted to a shape file, and then exported as an xyz file 

for use in the final gridding process (see Table 11).

Figure 16. Histogram of the differences between NOS hydrographic survey H09552 and the 1 arc-second presurfaced bathymetric grid.

3.3.4 Gridding the data with MB-System

MB-System (http://www.ldeo.columbia.edu/res/pi/MB-System/) was used to create the 1/3 arc-second 

Atlantic City DEM. MB-System is an NSF-funded share-ware software application specifically designed to 

manipulate submarine multibeam sonar data, though it can utilize a wide variety of data types, including 

generic xyz data. The MB-System tool ‘mbgrid’ was used to apply a tight spline tension to the xyz data, 

and interpolate values for cells without data. The data hierarchy used in the ‘mbgrid’ gridding algorithm, as 

relative gridding weights, is listed in Table 11. Greatest weight was given to the CSC LiDAR data. Least 

weight was given to the pre-surfaced 1 arc-second bathymetric grid. Gridding was performed in quads with

the resulting Arc ASCII grids seamlessly merged in ArcCatalog to create the final 1/3 arc-second Atlantic 

City DEM.

Table 11. Data hierarchy used to assign gridding weight in MB-System.

Dataset Relative Gridding Weight

CSC bathymetric–topographic coastal LiDAR 1,000,000

USGS NED topographic DEM 1000

Combined coastline 100

Pre-surfaced bathymetric grid 10
26 DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY

3.4 Quality Assessment of the DEM

3.4.1. Horizontal accuracy

The horizontal accuracy of topographic and bathymetric features in the Atlantic City DEM is 

dependent upon the datasets used to determine corresponding DEM cell values. Topographic features have 

an estimated accuracy of up to 10 meters: CSC bathymetric–topographic LiDAR data have an accuracy of 

approximately 6 meters; NED topography is accurate to within about 10 meters. Bathymetric features are 

resolved only to within a few tens of meters in deep-water areas. Shallow, near-coastal regions, rivers, and 

harbor surveys have an accuracy approaching that of sub aerial topographic features. Positional accuracy is 

limited by: the sparseness of deep-water soundings; potentially large positional uncertainty of pre-satellite 

navigated (e.g., GPS) NOS hydrographic surveys; and by the morphologic change that occurs in this 

dynamic region.

3.4.2 Vertical accuracy

Vertical accuracy of elevation values for the Atlantic City DEM is also highly dependent upon the 

source datasets contributing to DEM cell values. Topographic areas have an estimated vertical accuracy 

between 0.1 to 0.3 meters for CSC LiDAR data, and up to 7 meters for NED topography. Bathymetric areas 

have an estimated accuracy of between 0.1 meters and 5% of water depth. Those values were derived from 

the wide range of input data sounding measurements from the early 20th century to recent, GPS-navigated 

sonar surveys. Gridding interpolation to determine values between sparse, poorly-located NOS soundings 

degrades the vertical accuracy of elevations in deep water.
DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY 27

3.4.3 Slope maps and 3-D perspectives

ESRI ArcCatalog was used to generate a slope grid from the Atlantic City DEM to allow for visual 

inspection and identification of artificial slopes along boundaries between datasets (e.g., Fig. 17). The DEM 

was transformed to UTM Zone 18 coordinates (horizontal units in meters) in ArcCatalog for derivation of 

the slope grid; equivalent horizontal and vertical units are required for effective slope analysis. Threedimensional viewing of the UTM-transformed DEM was accomplished using ESRI ArcScene (e.g., Fig. 

18). Analysis of preliminary grids revealed suspect data points, which were corrected before recompiling 

the DEM. Figure 1 shows a color image of the 1/3 arc-second Atlantic City DEM in its final version.

Figure 17. Slope map of the Atlantic City DEM. Flat-lying slopes are white; dark 

shading denotes steep slopes; combined coastline in red.
28 DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY

Figure 18. Perspective view from the southeast of the Atlantic City DEM.

Vertical exaggeration–times 50.

3.4.4 Comparison with source data files

To ensure grid accuracy, the Atlantic City DEM was compared to select source data files. Files were 

chosen on the basis of their contribution to the grid-cell values in their coverage areas (i.e., had the greatest 

weight and did not significantly overlap other data files with comparable weight). A histogram of the 

differences between a CSC topographic LiDAR survey file and the Atlantic City DEM is shown in Figure 

19. Differences cluster around zero, with only a handful of soundings, in regions of steep topography, 

exceeding 0.5-meter discrepancy from the DEM.

Figure 19. Histogram of the differences between one CSC LiDAR survey and the Atlantic City DEM.
DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY 29

3.4.5 Comparison with NGS geodetic monuments

The elevations of 1247 NOAA NGS geodetic monuments were extracted from online shape files of 

monument datasheets (http://www.ngs.noaa.gov/cgi-bin/datasheet.prl), which give monument positions in 

NAD83 (typically sub-mm accuracy) and elevations in NAVD88 (in meters). Elevations were shifted to 

MHW vertical datum (see Table 10) for comparison with the Atlantic City DEM (see Fig. 21 for monument 

locations). Differences between the Atlantic City DEM and the NGS geodetic monument elevations range 

from -15 to 5 meters, with the majority of them being within + 2 meters. Negative values indicate that the 

monument elevation is less than the DEM (Fig. 20). Only 15 monuments out of 260 total showed 

significant deviations from the DEM. Such discrepancies are caused by the rough terrain in Atlantic City

area, where significant changes in local relief could occur on the scale of less then 10 meters.

Many monuments are mounted on buildings and bridges and were therefore not included in assessment

of the DEM.

Figure 20. Histogram of the differences between NGS geodetic monument elevations and the Atlantic City DEM.

Figure 21. Location of NGS geodetic monuments, shown as green triangles, and the NOAA Atlantic City tide 

station, yellow circle. NGS monument elevations were used to evaluate the DEM.
30 DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY

4. SUMMARY AND CONCLUSIONS

A bathymetric–topographic digital elevation model of the Atlantic City, New Jersey region, with cell 

spacing of 1/3 arc-second, was developed for the Pacific Marine Environmental Laboratory (PMEL) 

NOAA Center for Tsunami Research. The best available digital data from U.S. federal, state and local 

agencies were obtained by NGDC, shifted to common horizontal and vertical datums, and evaluated and 

edited before DEM generation. The data were quality checked, processed and gridded using ESRI ArcGIS, 

FME, GMT, MB-System and Quick Terrain Modeler software. 

Recommendations to improve the Atlantic City DEM, based on NGDC’s research and analysis, are listed 

below:

• Conduct hydrographic surveys for near-shore areas especially in bays and estuaries.

• Complete topographic LiDAR surveying of entire region especially at coastal marshes.

• Process CSC bathymetric–topographic LiDAR data to bare earth.

5. ACKNOWLEDGMENTS

The creation of the Atlantic City DEM was funded by the NOAA Pacific Marine Environmental 

Laboratory. The authors thank Chris Chamberlin and Vasily Titov (PMEL); LTjg David Fischman, 

NOAA/NESDIS/NGDC/MGG; NOAA Atlantic Hydrographic Office staff; and Monica Chasten, Harry 

Friebel, and Joe Scolari, USACE Philadelphia District Office.

6. REFERENCES

Nautical Chart #12214, 9th Edition, 2007. Cape May to Fenwick Island. Scale 1:80,000. U.S. Department 

of Commerce, NOAA, National Ocean Service, Coast Survey.

Nautical Chart #12300, 12th Edition, 2007. Approaches to New York Nantucket Shoals to Five Fathom 

Bank. Scale 1:400,000. U.S. Department of Commerce, NOAA, National Ocean Service, Coast 

Survey.

Nautical Chart #12304, 8th Edition, 2007. Delaware Bay. Scale 1:80,000. U.S. Department of Commerce, 

NOAA, National Ocean Service, Coast Survey.

Nautical Chart #12318, 1st Edition, 2007. Little Egg Inlet to Hereford Inlet. Scale 1:80,000. U.S. 

Department of Commerce, NOAA, National Ocean Service, Coast Survey.

Lathrop, Richard G., Paul Montesano, Scott Haag, 2003, Submerged Aquatic Vegetation Mapping in the 

Barnegat Bay National Estuary Update to Year 2003, http://crssa.rutgers.edu/projects/runj/bbay.html
DIGITAL ELEVATION MODEL FOR ATLANTIC CITY, NEW JERSEY 31

7. DATA PROCESSING SOFTWARE

ArcGIS v. 9.2, developed and licensed by ESRI, Redlands, California, http://www.esri.com/

FME 2007 GB – Feature Manipulation Engine, developed and licensed by Safe Software, Vancouver, BC, 

Canada, http://www.safe.com/

GEODAS v. 5 – Geophysical Data System, shareware developed and maintained by Dan Metzger, NOAA 

National Geophysical Data Center, http://www.ngdc.noaa.gov/mgg/geodas/

GMT v. 4.1.4 – Generic Mapping Tools, shareware developed and maintained by Paul Wessel and Walter 

Smith, funded by the National Science Foundation, http://gmt.soest.hawaii.edu/

MB-System v. 5.1.0, shareware developed and maintained by David W. Caress and Dale N. Chayes, 

funded by the National Science Foundation, http://www.ldeo.columbia.edu/res/pi/MB-System/

Quick Terrain Modeler v. 6.0.1, LiDAR processing software developed by John Hopkins University’s 

Applied Physics Laboratory (APL) and maintained and licensed by Applied Imagery, 

http://www.appliedimagery.com/