How To: Calculate mean sea level values from altitudes using a high-accuracy receiver connected to Collector for ArcGIS
Collector for ArcGIS stores altitude values representing Height Above Ellipsoid (HAE) instead of Mean Sea Level (MSL). The antenna height value associated with or entered for the receiver is used to subtract the incoming altitude values to ensure accuracy at the ground level.
A field can be created to record MSL values, which are calculated using the following formula:
Z-value (MSL) = HAE - geoid separation – antenna height
This formula must be configured manually in ArcMap or incorporated into the CollectorUtils scripts available on GitHub.
From the Catalog window, connect to the folder containing the toolbox.
Open the ProjectZ tool.
Input the required parameters, as listed below, and click OK. The following image is an example of the parameter values.
Input Coordinate System (of the x, y, z values)
Output Dataset or Feature Class
Output Coordinate System
Download the relevant le*binary GEOID12B file here. Determine the appropriate grid using this image.
Add the downloaded GEOID12B .bin file to ArcMap by creating a connection to the file in the Catalog window and dragging the .bin file to the map frame.
Project the GEOID12B .bin file to the same coordinate system as the data using the Project Raster tool. The .bin file projects on-the-fly when added to the map, which may add some degree of inaccuracy for the geoid height if the layer is not reprojected.