Vertical space: elevation, altitude, and depth
Add the vertical dimension without mixing up ground height, object altitude, and depth below a surface.
Why this matters
Two observations can share the same latitude and longitude while occurring on the ground, above it, at the water surface, or below it. A third coordinate is useful only when its vertical meaning and reference are understood.
Learn it
Elevation commonly describes terrain or feature height relative to a vertical reference. Altitude commonly describes an object above a reference. Depth describes distance below a reference surface or datum. For Ocean Idea Machine, Z+ is a convenient teaching label for above-surface, Z0 for the surface, and Z− for below-surface context; it does not replace the real vertical datum or reference that a dataset requires.
Work through an example
A camera on a pier, a surface buoy, and an underwater sensor can share a horizontal position but have very different vertical contexts.
Z+ above the chosen surface
Z0 at the surface
Z− below the surface
Always preserve the actual vertical reference.Practice
- 1Describe one above-surface, one surface, and one below-surface observation.
- 2For each, name the vertical value and the reference you would need to interpret it.
- 3Decide whether the value belongs in geometry, properties, or both for your data format.
What to watch for
A number such as “12” is not enough. Twelve meters above what? Twelve meters below which surface? Preserve the reference.
Where this takes you
Vertical context matters for terrain, aviation, ocean observations, bathymetry, underwater vehicles, infrastructure, and 3D presentation.