Compass Azimuth in Site Photos: What It Is and How to Read It

Azimuth is the compass direction the camera was pointed when a photo was taken, measured in degrees clockwise from north — 0° is north, 90° is east, 180° is south, 270° is west. On a site photo, it answers a question coordinates alone can't: not just where you were standing, but which way you were facing when you took the shot.

Why azimuth matters for field photos

Two photos taken from the exact same coordinates can show completely different things depending on which direction the camera faced — the north wall of a structure versus the south wall, one property boundary versus the adjacent one. For inspections, defect documentation, and any photo where "what am I looking at" matters as much as "where was this taken," azimuth removes the ambiguity.

True heading vs magnetic heading

This is the part that trips people up. There are two different "norths":

• True north — the direction to the geographic North Pole, what maps and coordinate systems are based on.
• Magnetic north — the direction a compass needle points, which is offset from true north by an amount that varies by location (called magnetic declination) and shifts slowly over time.

A phone can calculate true heading by combining its magnetometer reading with its GPS location (to look up the local declination) and orientation sensors. When that calculation isn't available or reliable — often due to nearby metal, hardware limitations, or a location fix that hasn't settled — apps fall back to raw magnetic heading instead.

Reading the ≈ symbol

A well-built app marks the difference visibly: a plain heading like 216° means true heading was available and used. A heading shown as ≈216° (with a tilde/approximation symbol) means the app fell back to magnetic heading, which can be off from true north by anywhere from a few degrees to over 20° depending on your location on Earth.

Why phone compasses drift in the first place

• Nearby ferrous metal — rebar, vehicles, structural steel, even some phone cases can distort a magnetometer reading.
• Uncalibrated sensors — phone compasses periodically need recalibration (the figure-8 motion prompt), and skipping it degrades accuracy.
• Hardware limitations — consumer phone magnetometers are not survey-grade instruments; expect real-world accuracy in the range of several degrees even when working correctly, and up to roughly ±10° in less favorable conditions.

How to use azimuth data responsibly

1. Treat it as a field reference, not a survey measurement — useful for orientation and context, not for anything requiring true directional precision like a formal boundary determination.
2. Watch for the approximation symbol and note when a reading fell back to magnetic — it changes how much you should trust the exact number.
3. Calibrate your device's compass periodically, especially after being near strong magnetic sources.
4. For anything requiring true survey-grade bearing accuracy, use dedicated survey equipment — a phone compass stamp documents context, it doesn't replace a total station or calibrated compass for formal measurements.

Azimuth is one of several fields worth getting right on a field photo — see proof-of-work photos for field inspections for the full list, and GPS EXIF data explained for how location and heading actually get stored in the file.