A user-friendly implementation of the NGS VERTCON transformation from NGVD 1929 to NAVD 1988 vertical datums in the contiguous United States.
The VERTCON model was developed by the US National Geodetic Survey. The source for that version (2.1) is available here. The NGS's web tool is here. The original VERTCON 2.1 README is included in this repository.
VERTCON represents the difference between the NAVD 1988 and NGVD 1929 datums. This value varies over the country, which the original developers represented in a 3-minute grid across the country. The value for a given point is bilinearly interpolated from the values of the surrounding cells. While the grid is slightly larger than the contiguous US, values outside the US should not be considered valid.
Clone the repo and navigate to the directory.
Set up a virtual environment:
virtualenv venv
or
python3 -m venv ./venv
Install the packages:
pip install -r requirements.txt
And run with either
python3 app.py (for debug mode)
or
gunicorn app:app (for production mode)