Introducing Vertical

Transformations in ArcGIS

Melita Kennedy

Vertical Coordinate System (VCS)

• Defines the origin for height or depth

The Origin for Height or Depth

Geometric model

Earth’s surface

ellipsoid

The Origin for Height or Depth

Geometric model

Gravity related model

geoid

Earth’s surface

ellipsoid

Gravity-Related Earth Model

• Geoid

- Global representation of mean sea level

- Complex shape

- Modeled with geoid height / undulation (N)

Vertical Coordinate System

Vertical Coordinate System

Datum or

Vertical Datum

DirectionVertical Shift

Linear Unit

Datum vs. Vertical Datum

• Datum

- Ellipsoidal datum

- Ellipsoidal height (h)

• Vertical datum

- Gravity-related datum

- E.g. orthometric height (H)

Direction and Shift

• Direction

- axis direction is positive for heights or depths

• Vertical Shift

- parameter for a built-in offset from

the VCS definition

Vertical Transformations

Ellipsoidal Heights (NAD83)

Orthometric Heights (NAVD 88)

NAD_1983_To_NAVD88_

CONUS_GEOID12B_Height

Vertical Transformation Methods

Geoid models

EGM2008

EGM84 and EGM96

GEOID12B

VERTCON

Vertical offset

Vertical offset and slope

• Between ellipsoidal and gravity related heights

• Used with GNSS

Types of Vertical Transformations

GCS A / VCS 1

GCS A / VCS 2

Vertical transformation

using geoid model

• Between two geographic coordinate systems

• Heights are ellipsoidal

Types of Vertical Transformations

GCS B / VCS B3D Geog. Transformation

GCS A / VCS A

• Between two gravity related heights

Types of Vertical Transformations

Vertical

Transformation

GCS A / VCS 1

GCS A / VCS 2

• Between two gravity related heights

• May require interpolation GCS

Types of Vertical Transformations

GCS A / VCS 1

GCS A / VCS 2

• Between two gravity related heights

• May require interpolation GCS

Types of Vertical Transformations

GCS C / VCS 12D Geog. Transformation

GCS A / VCS 1

GCS A / VCS 2

• Between two gravity related heights

• May require interpolation GCS

Types of Vertical Transformations

Vertical

Transformation

GCS C / VCS 1

GCS C / VCS 2

2D Geog. TransformationGCS A / VCS 1

GCS A / VCS 2

• Between two gravity related heights

• May require interpolation GCS

Types of Vertical Transformations

Vertical

Transformation

GCS C / VCS 1

GCS C / VCS 2

2D Geog. TransformationGCS A / VCS 1

~2D Geog. TransformationGCS A / VCS 2

ArcGIS

Coordinate

Systems

Data

ArcGIS Coordinate Systems Data

• 1.5 GB additional data install

• GEOCON v1.0

- NAD 1983 HARN, NSRS2007, 2011

• NTv2 (CA, ES, CH, UK)

• VERTCON / GEOID12B

• Geoids (JP, NZ, CH)

• EGM2008 (1′ x 1′, 2.5′ x 2.5′)

Geographic

Transformations

Vertical

Transformations

Demo in ArcGIS Pro

Vertical

Transformations

Why couldn’t we transform a layer?

• Restricted to four (4) steps in a path

- 2 geographic

- 2 vertical

NAD 83 (2011)

NAD 1927

NGVD 1929

NAD 83 (2011)

Why couldn’t we transform a layer?

• Restricted to four (4) steps in a path

- 2 geographic

- 2 vertical

NAD_1927_To_NAD_1983_NADCONNGVD 1929

NAD 1927

NGVD 1929

NAD 1983

Why couldn’t we transform a layer?

• Restricted to four (4) steps in a path

- 2 geographic

- 2 vertical

NAD_1927_To_NAD_1983_NADCON

NGVD29_To_NAVD88_NAD83_ECW

NAD 1927

NGVD 1929 NAVD 1988

NAD 1983

Why couldn’t we transform a layer?

• Restricted to four (4) steps in a path

- 2 geographic

- 2 vertical

NAD_1927_To_NAD_1983_NADCON

NGVD29_To_NAVD88_NAD83_ECW

~NAD_1983_To_NAVD88_CONUS_GEOID12B_Height

NAD 1927

NGVD 1929 NAD 1983

NAD 1983

Why couldn’t we transform a layer?

• Restricted to four (4) steps in a path

- 2 geographic

- 2 vertical

NAD_1927_To_NAD_1983_NADCON

NGVD29_To_NAVD88_NAD83_ECW

~NAD_1983_To_NAVD88_CONUS_GEOID12B_Height

~WGS_1984_(ITRF00)_To_NAD_1983

NAD 1927

NGVD 1929 WGS 1984

WGS 1984

Why couldn’t we transform a layer?

• Restricted to four (4) steps in a path

- 2 geographic

- 2 vertical

NAD_1927_To_NAD_1983_NADCON

NGVD29_To_NAVD88_NAD83_ECW

~NAD_1983_To_NAVD88_CONUS_GEOID12B_Height

~WGS_1984_(ITRF00)_To_NAD_1983

WGS_1984_(ITRF08)_To_NAD_1983_2011

NAD 1927

NGVD 1929 NAD 83 (2011)

NAD 83 (2011)

More about Coord. Systems, Reference Frames, Transformations, Map Projections

• ArcGIS Pro Tips and Tricks:

Map Projections

• Coordinate Systems and Datum

Transformations in ArcGIS

• National Mapping Transformation with

New Terrestrial Reference Frame

• Geographic (datum) and Vertical

Transformations: A Deep Dive

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More about Coord. Systems, Reference Frames, Transformations, Map Projections

• Coordinate Systems and Datum

Transformations in ArcGIS

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