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Status
Tutorial
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FAQs
- What is the maximum file size that can be submitted to multipoint conversion?
NCAT allows up to 500K in file size
- WGS84 is not an option in the conversion tool. If I have records from all over the world then which NAD 83 do I use in place of WGS84?
For now, you may use HTDP to transform WGS84 to NAD 83 first and use the transformed NAD 83 coordinates in NCAT. Future versions of NCAT may support WGS84. You may access HTDP from here
- Is there a batch mode for the Web service or plans to implement one?
No, there is no batch mode for web service.
- Are the results from NCAT and VDatum the same?
NCAT and VDatum share the same codebase and the results should be consistent between them. If you notice any discrepancies, please let us know.
- I expect the NCAT output to have a combined scale factor, but it is missing. Is there something special that I have to do to get it to work?
An ellipsoid height is needed for combined scale factor computation. Please be sure to choose the horizontal+height option and enter a height.
- How can I convert an elevation measurement for my home based on mean sea level datum from 1929 to reflect a more recent datum?
Please access NCAT from here
Once the page comes up, please select horizontal+height from the top row. Select orthometric from the third row. Enter your latitude, longitude and orthometric height. Towards the bottom of the screen you see an option to choose an input geopotential or vertical datum. Pick NGVD 29 from the dropdown and click submit. You should see transformed height under "Transformed Coordinate". - Will NCAT convert today's data to the modernized NSRS (NATRF2022, NAPGD2022, etc.), once fully implemented?
Yes, it will. Please keep an eye out for news or product update announcements on our website.
- Is there a simple tutorial (or YouTube demo) on how to use the NGS Coordinate Conversion and Transformation Tool (NCAT)?
You can find tutorial videos at and click on the Tutorial & FAQ's tab.
- Could I get the coordinate conversion tool to give me lat/lon in degrees-minutes-seconds instead of decimals of a degree?
The tool does generate results in both decimal degrees and degrees-minutes-seconds
- Where can I access the source code for NCAT? The engine that powers NCAT, known as ncat-lib, is publicly available on github
- Which browser is recommended for NCAT?
While NCAT works on all browsers, legacy versions of IE have known issues. NGS recommends Chrome for the best user experience.
- Does NCAT convert between ellipsoid and orthometric heights?
The current version of NCAT does not support conversions between ellipsoid and orthometric height, but future versions will. For the interim, to compute an NAVD 88 orthometric height from an NAD 83 (2011) ellipsoid height please use the Geoid tool
- Is the web-based NCAT tool a replacement for Corpscon 6?
No. CORPSCON is an official U.S. Army Corps of Engineers product, not an NGS product. Though CORPSCON offered integrated NGS products long before NCAT it has always been under the control of USACE. Although NGS is not aware of any issues with CORPSCON integrating NGS products and services, the only official tools NGS endorses for use in the NSRS are those directly under NGS control, such as NCAT.
- It appears that the NAD 27 to NAD 83(1986) transformation changed when comparing NADCON 4 (or NADCON 2.1 which I believe was used in Corpscon 6) vs. NCAT’s results. Is there documentation as to why these two superseded systems would experience a change in transformation results?
NADCON 5.0 release 20160901 supersedes all previous versions of NADCON. Minor differences are possible between NADCON 5.0 release 20160901 and legacy versions. NOAA Technical Report NOS NGS 63 (PDF, 17 MB) provides detailed information on NADCON 5.0 release 20160901 (including why these differences exist), and the digital archive includes plots and data.
- Is NCAT a replacement tool for Corpscon version 6?
NGS, the authoritative source for conversions/transformations grids, provides through its NCAT program the latest transformation grids for horizontal and vertical transformations. Industry or other agency conversion/transformation tools such as Corpscon version 6 (which is maintained by the U.S. Army Corps of Engineers) and others may or may not incorporate the latest grids. As such use of NCAT is strongly encouraged.
NGS Coordinate Conversion and Transformation Tool (NCAT) allows users to easily convert between different coordinate systems and/or transform between different reference frames and/or datums, in a single step. For coordinate conversion, NCAT allows conversion between lat/long/height, SPC, UTM, XYZ, and USNG systems. NCAT currently uses NADCON* to perform three-dimensional (latitude, longitude, ellipsoid height) coordinate transformations and VERTCON* to perform orthometric height transformations. Transformations are provided for a wide range of frames/datums and regions in the National Spatial Reference System. NADCON and VERTCON provide local error estimates for each transformation, and do not support transformations which are outside the boundaries of the supported areas (generally, CONUS, Alaska, Hawaii, Puerto Rico and the US Virgin Islands, American Samoa, and Guam and Northern Mariana Islands).
Please note that, although either orthometric or ellipsoidal heights can be used as inputs to NCAT, at this time NCAT does not convert between orthometric and ellipsoidal heights. Only orthometric-to-orthometric and ellipsoidal-to-ellipsoidal height transformations are currently possible in NCAT.
NCAT incorporates the capabilities of the following NGS computer programs, which originally were stand-alone products:
- XYZ Coordinate Conversion (XYZWIN 2.0)
- Universal Transverse Mercator Coordinates (UTMS 2.1)
- State Plane Coordinates, NAD 83 (SPC83 2.1)
- State Plane Coordinates, NAD 27 (GPPCGP 2.0)
- U.S. National Grid (USNG 2.3)
- Latitude,Longitude,and Ellipsoid Height Transformations (NADCON)
- Orthometric Height Height Transformations (VERTCON)
* See ChangeLog for information on the currently implemented releases of NADCON and VERTCON.
Version 2.1 View ChangeLog
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