Is there a web site to convert veritical datum from 29 to 88
Vertcon on www.ngs.noaa.gov
Howdy,
Yes, VERTCON is the official federal government conversion tool. Not knowing your accuracy requirements I cannot determine whether it is appropriate for your work. Use the Search tool on this site and you'll find a lot of good information about its limitations.
Cheers,
DMM
I notice that the FEMA flood panel maps give a conversion factor (county wide) for converting 29-88
Howdy,
No doubt there are many approximate conversion factors, offset values from a variety of sources. The official US government Federal Register note is available here: http://www.ngs.noaa.gov/PUBS_LIB/FedRegister/VERTCON_FRN.pdf
As it indicates, a mathematical transformation tool like VERTCON is not the best method to accurately determine an NAVD88 value from an NGVD29 value.
The notice includes the following: " In order to maintain consistency of results and to minimize misuse associated with the mathematical transformation method, FGCS recommends software identified as VERTCON (Vertical Conversion) as a Federal standard."
A county-wide conversion factor is new to me. I do not deal with FEMA. Since I have retired I have attempted to limit contact with those things that annoy me...
Cheers,
DMM