CSV export

Since the Surveyor is a multi-beam echo sounder, each time we emit a sonar pulse, we receive multiple signals and combine them to get multiple beams. Each ping consists of multiple “detections” and each detection is a row in the CSV.

Some data is per-detection, and some is per-ping.

The following columns are presented in CSV export:

column	notes
latitude	detection's geodetic latitude in decimal degrees north of equator (or negative south)
longitude	detection's geodetic longitude in decimal degrees east of prime meridian (or negative west)
altitude (m)	height of detected point above sensor. Will be negative.
northing (local m)	detection's Cartesian position in meters north. Relative to an arbitrary origin.
easting (local m)	detection's Cartesian position in meters east. Relative to an arbitrary origin.
ping number	sequence number of the ping which produced this data. Each ping has multiple detections, and thus multiple rows in the CSV.
elapsed (s)	time the ping was sent, in seconds since the session started
datetime	time the ping was sent, in UTC
altitude (m above MSL)	Altitude of the point relative to Mean Sea Level.
northing (UTM m)	detection's georeferenced Cartesian position
easting (UTM m)	detection's georeferenced Cartesion position
coordinate projection	Which UTM zone the georeferenced coordinates are in

Note that all positions and altitudes are those of the detected points, not those of the vehicle.

If the surveyor is mounted 0.5 below the vehicle center and a point is 10m down below the sensor then altitude (m) will be -10.5. Furthermore, if the GPS reports that the vehicle is 30m above MSL, then altitude (m above MSL) will be 20.5.