A Checklist for Geotagging Your Field Photos

You find a clean fold in a sea cliff. The light is flat and kind, the beds are washed clear, and you take twelve photographs before the tide turns. Nine months later you are trying to find that fold again, and you have twelve pictures of grey rock with no idea whether you were at the north end of the bay or the south. Location, scale and orientation are the three things field photographs lose first, and they are the three things that make a photograph geological rather than decorative. Here is a checklist you can work through at every stop.

Record the location three ways

One method will fail. Two might hold. Three will survive a lost notebook, a dead phone or a corrupted card.

First, take a waypoint at every stop rather than every photograph. Name or number it in the device so that it matches the stop number in your notebook. If you are working on a site you will revisit, note the grid reference as well; for much of the UK that means an OS grid reference, and it is worth writing both the grid reference and the latitude and longitude if your software uses one and your map uses the other.

Second, write it down. Pencil, paper, no battery. Record the grid reference, the stop number, the time and a plain description of where you were standing, not just what you were looking at. "Photographs taken from the path 20 m east of the exposure, looking west" is worth more than any amount of clever naming later.

Third, photograph the evidence. Make the first frame at each stop a picture of the GPS screen or the notebook page showing the stop number and grid reference. It feels fussy standing in the rain. It takes four seconds, and it ties your whole sequence of files to a place without any guessing.

A contextual detail helps too: a gate, a bothy, a distinctive fence corner, a road sign. Anything you could walk back to and recognise.

Put a scale in the frame, in the right plane

A rock photograph without a scale tells a reader nothing about size. A fold a metre across and a fold a hundred metres across can look almost identical through a lens, because the camera has no way of knowing.

• A geological hammer, for anything from a hand specimen to a large outcrop.
• A lens cap or camera body cap, for the middle range.
• A hand lens: measure yours once and write the diameter in permanent marker on the rim, so you always know what it is.
• A grain-size card or comparator for sediment, where the grain size matters more than the outcrop.
• A tape measure or folding rule for fine detail, particularly cross-bedding and thin veins.
• A person, for large structures. Ask them to stand still and, if you can, to wear something bright.

Lay the scale against the feature, in the same plane as the surface you are photographing. A coin held out towards the lens on a bedding plane, ten centimetres in front of the rock, will mislead the reader about both grain size and thickness. If the surface is vertical, hold the scale flat against it. If you are photographing a vertical face from below, say so in your notes, because the foreshortening will not be obvious from the image alone.

Write the scale item down anyway. Photographs get cropped, coins get pocketed, and a reader who cannot see the hammer needs to be told it was there.

Fix the orientation

Every photograph should answer a second question: which way was the camera pointing? Without that, a bedding plane and a joint surface can be confused, and a dip direction becomes a guess.

Record the bearing of your view direction as a compass bearing, and note it in the same breath as the stop number. If your compass has a clinometer, take the strike and dip of the face you are photographing as well. Even when you have not measured a structure formally, note whether you are looking at a cross-section through the beds or along the bedding surface; that one sentence saves a great deal of argument later.

Where the terrain allows, include something that gives the reader their bearings: a horizon, a distant headland, a coastline running away to the left, a tree line. Photographing a vertical face straight on with nothing else in the frame removes every clue about which way it faces.

Crop away the sky and the sea and you have removed the only parts of the picture that told the reader where the camera was standing.

The three-frame routine at every stop

Once the routine is fixed, you stop having to think about it. At each stop, work through these in order.

1. Context. A wide shot showing the whole exposure, with a scale — a person or a hammer — and a landmark somewhere in the frame. Note the bearing.
2. The exposure. A middle-distance shot of the face you have come to see, scale card in position, taken square on so the geometry is honest.
3. The detail. Close in on the specific feature: the hinge of the fold, the sole marks, the chilled margin. Scale in the plane of the surface, and take a second frame with a different scale item if there is any doubt.
4. The record shot. GPS screen or notebook page, showing stop number, grid reference and the notes you have just written.

Then write the stop number, bearing, grid reference and a one-line lithology description in the notebook before you move on. The walk back to the vehicle is the last place you will remember any of it.

Filenames, clock drift and the evening sort

Use your stop numbers in the file names. Something like ST04_002_face-lookingNE_ruler.jpg is ugly and immensely useful; a folder of IMG_4471.jpg is neither. Keep one folder per day or per locality, and keep the numbering consistent across notebook, GPS and files.

If your camera does not have GPS, you can attach locations from a tracklog afterwards, but only if the clocks agree. Check the camera clock against your phone at the start of the day and note any offset. A camera that is four minutes fast will place your photographs a few hundred metres from where you took them, which is exactly the sort of error that is invisible until it matters.

Back up the card and write up your notes the same evening, while the confusion is still fresh. If you are unsure about something, photograph it again the next morning rather than trying to reason it out from a blurry frame in three months' time.

The field card

Copy this onto a card, tape it inside your notebook cover, and glance at it before you put the camera away.

• Waypoint taken and numbered.
• Grid reference written in the notebook.
• Screen or notebook page photographed as the first frame of the stop.
• Scale in the frame, in the plane of the surface, and named in the notes.
• Bearing recorded; strike and dip recorded if measured.
• Context shot, exposure shot, detail shot, record shot.
• Files named with the stop number; card backed up.

None of it takes long. Five extra minutes at an outcrop buys you a photograph that can still be used, described and argued over years later — which is the whole point of carrying a camera into the field in the first place.

Photo: TheAngryTeddy / Pixabay