Online VDatum: Vertical Datums Transformation

Online Vertical Datum Transformation
Integrating America's Elevation Data

Regional Information


* Region :

Horizontal Information

	Source	Target
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Zone:

Vertical Information

	Source	Target
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Unit:
	Height Sounding	Height Sounding
	GEOID model:	GEOID model:

Ellipsoidal Transformation Epoch Inputs

To provide data transformations with closer agreement to those produced by the NGS HTDP program. VDatum now allows the user to specify the input and output epochs of positions. These epochs will be used to apply a time-dependent, 14 parameter transformation that utilizes HTDP 3.5.0-predicted velocities, where available. If the user does not specify input and output epochs, they will be handled as described below.

Non-User Specified input and output epochs of positions:

If a user does not specify an input or output epoch for positions, the following will be utilized by default as the input epoch and the output will be established based on your computer time and date:
◉ 2000 for the following frames: IGS20, ITRF2020, IGS14, ITRF2014,IGS08, ITRF2008, IGb08, ITRF2000, ITRF2005, WGS84 (G1674), and WGS84 (G1762)
◉ 1997 for all NAD83 (2011/CORS96/2007; PA11/PACP00; MA11/MARP00) realizations, ITRF97, WGS84 (transit).
◉ 1996 for ITRF96
◉ 1988 for ITRF88, ITRF89, ITRF90, ITRF91, ITRF92, ITRF93

User Specified input and output epochs of positions:

Dates may be entered either in the month-day-year format or in the decimal-year format. For the month-day-year format, the month is a number between 1 and 12 and a four-character year is required. The month, day, and year may be separated by spaces or by commas. Valid examples are: 5,4,1998 for May 4, 1998.

For the decimal-year format, enter yyyy.xxx where yyyy denotes the year and xxx denotes the fraction of the year. Valid examples are:

2010.0 for January 1, 2010
1979.359 for May 12, 1979

The decimal point is required but the precision of the fractional year is optional. The fractional year is obtained by subtracting one from the day-of-year and then dividing the result by 365 (or 366 if it is a leap year). Thus, the fractional year corresponds to UTC midnight at the beginning of the day.

month-day-year

decimal year

Specify the reference date of the input position(s) :
Specify the reference date of the output position(s):

Note: Remove output position reference date to proceed with default epoch positions.

Point Conversion
ASCII File Conversion

	Input
Latitude:		Latitude:
	e.g. 33.7586 or 33 45 30.9600
Longitude:		Longitude:
	e.g. -118.7691 or -118 46 8.7600
Height:		Height:
	e.g. 3.037

	to DMS
Vertical Uncertainty:	1 sigma 95% Confidence
	Add Observation Vertical Uncertainty
	(expecting 1 sigma input)