Terrasolid and NAVD88 - Geoid18

Darrick Wagg, Support Manager

October 2019 Newsletter Article

On September 13, 2019 the National Geodetic Survey (NGS) released the Geoid18 model for the North American Vertical Datum of 1988 (NAVD88), the Puerto Rico Vertical Datum of 2002 (PRVD02), and the Virgin Islands Vertical Datum of 2009 (VIVD09).Accordingto the NGS, “GEOID18 does NOT cover Alaska, Hawaii, Guam and the Commonwealth of the Northern Mariana Islands (CNMI) where users should continue to use GEOID12B”. The Terrasolid Adjust to Geoid tools are not directly compatible with the formats of the geoid files as released by the NGS. Neither is TerraScan’s Convert geoid Model tool. Hence, users must create their own adjustment file for taking data from ellipsoidal to orthometric elevations. For users of the GeoCue workflow management and LP360 software, this will not be necessary as both of those products will support vertical datum transformations using Geoid18 in their upcoming releases expected close to the end of this year. For users with a developer on staff they can easily create a conversion tool to convert the NGS released ASCII formatted files to a Terrasolid compatible adjustment file. For those users which do not fall in either of those categories, we have a workflow on how to create a geoid adjustment file for your project area on our searchable support knowledge base, which uses the INTG program distributed by the NGS. For any questions about geoid adjustments in the Terrasolid products please contact support@geocue.com.