Field tool · worn inscriptions

Rakelight

Weathered stone still holds its letters as shape. Move the light, not the camera, and the shape comes back.

Carving a stone…
Flat light — as photographed

What this does

The letters never left.
They stopped being visible,
not present.

What the light just read

    A worn inscription is not gone. It is depth — a few tenths of a millimetre of it. Overhead light falls on the carving and the walls of the letters equally, so it disappears. Light coming in almost sideways catches one wall and shadows the other, and the letters come back.

    The stone above is generated, not photographed — so nothing here is a before/after trick.

    If the quick look isn't enough

    Four slower methods, in order of how much they ask of you.

    The quick look strips colour away, which is usually enough to tell whether there is anything there. It cannot recover depth — for that the light has to move, and moving the light costs time. Start at the top and only go further down if you have to.

    When to stand here

    The sun rakes this face for about an hour a day. Here is when.

    Set which way the inscribed face looks. Rakelight works out when the sun will graze it today — the only daylight that reveals worn carving.

    180°
    Face looks S

    Drag the dial, or focus it and use the arrow keys. A stone you read while facing north is a stone that faces south.

    Lock your exposure before you shoot. Press and hold on the stone in the camera app until it says AE/AF LOCK. Auto-exposure silently rebalances every frame and erases the exact shading differences this tool reads.
    Outside the window? Don't wait. Bright overhead sun is the worst light for reading stone and the best light for Shadow scan — the harder the sun, the crisper the shadow edge you sweep across the face. Flat overcast is the one condition neither method likes; that is when a torch after dusk wins.

    Bright sun · works at noon

    You can't move the sun. You can interrupt it.

    Sweep a hard shadow across the stone while recording. Rakelight times when the edge crosses each pixel; carving lags. That lag is depth — a measured height map, not a shading trick.

    What to bring. Anything with a straight edge: a clipboard, a book, a folded map, a hat brim, your own forearm. Hold it close to the stone — about a hand's width out. Far away the shadow goes soft and the reading blurs.
    1. Wedge the phone steady, square to the face. A bag, a kerb, another stone.
    2. Press and hold on the stone until it says AE/AF LOCK. This matters more here than anywhere else.
    3. Start. Hold the edge just outside the frame so the whole face is in sun.
    4. Sweep the shadow steadily across the face — 8 to 12 seconds, one direction, don't stop, don't reverse. Perpendicular to the lines of text works best.
    5. Keep going until the whole face is shaded.

    Or bring a video you already shot.

    No video to hand? and watch the timing solve.

    No sweep recorded yet.
    —°
    Virtual light

    Once depth is solved the light is yours. Rake it from any side, including sides the sun never reaches from.

    If it comes out as noise. Almost always one of three things: the phone moved, exposure wasn't locked, or the sweep reversed direction. Trust mode shows which pixels never saw a clean shadow crossing — if it is mostly orange, the sweep didn't cover the face.

    Multi-light capture

    Hold the camera still. Walk the light.

    Have someone carry a torch in a slow circle around the stone while you record — or shoot 8–20 stills as the light moves. Rakelight learns the surface from how the shadows change, then lets you light it from anywhere, including from angles the sun can never reach.

    Drop a video, or 8–20 photos.
    Same camera position, moving light.

    Nothing to upload? .

    No surface loaded yet.
    —°
    Light from

    The amber marks are light you actually captured. Between and beyond them Rakelight is extrapolating — trust it less.

    Logged stones

    Single photograph

    One flat photo, and honest limits.

    One photograph cannot be truly relit — the shadow information was never recorded. What it can do is separate faint carving from stone colour and lichen stain. Use this when you only get one pass at something.

    One photo. Sharp, filling the frame, shot square-on.

    No photograph loaded yet.
    Why this is the weak one. Incised letters survive as depth, not as darkness. A flat photo records only colour, so these filters amplify whatever tonal trace is left — real carving and lichen edges alike. Treat the result as a hint to come back under raking light, not as a reading.

    Field order. Check the light window. Lock exposure. Shoot the multi-light pass. Relight it on the spot — if it is still unreadable, log it and come back at the hour the chart gives you.

    Never chalk, flour, shaving cream or rub a historic stone. It drives salts and grit into failing surfaces and is banned in most burial grounds. Light costs the stone nothing.

    Works offline once loaded — save it to your home screen before you lose signal.

    What's the light doing right now?

    Look at the ground. The answer is whether things are casting shadows.

    3
    Fill the frame with the stone. Then wedge the phone somewhere it won't move.
    Relit inscription, magnified
    Scroll to move around
    Straight off the camera

    Fill the frame with the stone and hold still for a moment.

    Colour removed

    Fourteen frames stacked and aligned against your hand shake. Press and hold the picture to see what the camera actually saw.