Free Online Outcrop Photo Annotator: Scale Bar and North Arrow
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Choose a photo or load the demo. Your image never leaves this page.
The photo that explains itself
Every geologist has a phone full of outcrop photos that made perfect sense on the day and none whatsoever a month later. Which way was north? How big is that channel? Which bed was the coal? This annotator fixes all three in about a minute: drop the photo in, place a scale bar, spin the north arrow to match your compass reading, and click anywhere to plant a label. Export the result as a PNG that can go straight into a report, a thesis figure, or a message to a colleague, and still make sense years from now.
How to use it
Load a photo, or press the demo button for a synthetic outcrop to practice on. Type your label text, choose a size, and click the photo where the label belongs: white text with a dark outline stays readable over any rock color. The scale bar sits bottom left with an adjustable length and whatever label fits your scene, one meter or ten centimeters or a lens cap. The north arrow sits top right and rotates to any bearing, so a photo taken facing southwest can still carry true orientation. Undo removes the last label if your click wandered.
Field kit, part three
Together with the phone clinometer and the GPS waypoint logger, this completes a free field kit that lives entirely in the browser: orientation measurements, positioned stations, and self documenting photographs, with nothing installed and nothing uploaded. The photo is processed on your device from first pixel to exported PNG, which matters when the outcrop is on a client site or a competitive license.
Honest limits
The scale bar is only as honest as you are: it marks a length you assert, not one the tool measures, so estimate against a hammer or a person in frame. The arrow marks the bearing you give it. This is annotation, not photogrammetry, and that is exactly why it stays fast.
Related Calculators and Reference
- Phone Clinometer and Compass: measure the strike and dip you are photographing.
- GPS Waypoint Logger: record where every photo was taken.
- Soil Description Generator: put standard words next to the picture.
- Demo Valley Worked Project: where field records end up.
- USGS: masters of the well documented field photograph.