How we build the models

Each type page shows a 3D model of one found coin: a real coin, made from the front and back photographs of that coin. Most are finds recorded by the Portable Antiquities Scheme; where a museum's openly licensed photograph of the type is much clearer, we use that coin instead (two types).

We have taken our as-minted reconstructions (how a coin may have looked when newly struck) off the site for now.

What the photographs can and cannot tell us

A photograph shows the outline and the design clearly, but not depth. We estimate relief from light and shade in the photograph. That depth is inferred: it is not measured, and the models are not scans or replicas.

Size

Where the record gives a diameter, the model is that size. Where it does not, we measure the scale bar in the photograph; on the coins with recorded diameters this method came within about 3 to 8 per cent. Thickness is only measured on one coin; elsewhere it is worked out from the recorded weight and an assumed density for the broad metal, or set from the diameter where no weight is recorded. Labels on the model quote recorded figures only.

Feature labels

Each marked feature says how much of it survives on the found coin: survives, partly visible or not visible. Features named in the find record but not visible are listed as record only.

Found examples and dies

Each coin page also shows other coins of the same type from openly licensed photographs, grouped by die where we can tell. Die labels are our own provisional labels, one scheme per coin; they are not published die numbers. Coins whose photographs have no open licence are counted but not shown.

Orientation of the two faces

We place the reverse relative to the obverse by matching the outlines of the two photographs. Where a record gives a die axis we check against it.

Tools

Models are built in Blender and shown with three.js (MIT licence).