Introducing Vertical Transformations in ArcGIS Melita Kennedy
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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