Tag Archives: NMEA

NMEA 0183 Reference

nmea_logo

The human brain is amazing in that is can process text and discern meaning.  Computers are getting better but they still have a long way to go.  So when it comes to writing simple programs that can interpret files and easily extract data from one or more sensors of one or more types, having standardized formats are clutch.

The National Marine Electronics Association (NMEA) exists to develop, define and promote many of the data format standards that ship operators depend on to safely operate their vessels.  Turns out oceanographers depend on them a lot too.  To that end I’ve compiled a list of NMEA-defined standardized data strings for sensors commonly used in oceanographic research.

If you have an additional NMEA string you would like added please let me know in the comments.

I hope this helps,
– Webb

 

Bulk Geo-Tagging of Images Using SCS Timestamped NMEA GGA, HDT and ROV Data

The idea idea of Geo-Tagging or Geo-Referencing images is straight forward; embed time and position information into an image file so that you know when and where the image was taken without having to keep track of the information externally.  It is a technique that is widely used among professional and amateur photographers alike to show where their photos were taken.  Technically speaking, geo-tagging is the process of populating storage bins in the image file’s metadata header with GPS time, longitude, latitude, heading (true or magnetic), and altitude (above or below sea level).  This metadata header is only present on PSD, JPEG and TIFF image types so the techniques discussed here will only work on those files. Continue reading

Convert SCS timestamped NMEA GGA data to KML

Overview

For better or worse Google Earth is becoming the defacto standard for geospatial visualization.  I’m guessing this is due to the amazingly powerful and beautiful yet intuitive user interface (giving credit where credit is due).  Regardless of the reasoning, for the near future Google Earth is going to be how most people prefer to show off their GIS data and the interest of being good datarats we should try to figure out how to accommodate our scientists. Continue reading