This dataset contains limb models scanned using the EINScan Pro 2X Plus scanner. At each of 3 sites, operator 1 (OP1) scanned the four limb models twice (OP1-A and OP1-B) with the structured-light scanner, and operator 2 (OP2) scanned the four limb models once with the same scanner, for a total of 12 scans per site. At the European site, an additional reference scan of each positive model (4 scans) was conducted by an independent professional Operator (OP0) using the metrological scanner (EINScan Laser FreeScan 5X). 

All limb models were scanned using the EINScan Pro 2X Plus with added HD Prime Pack (SHINING 3D Tech. Co. Ltd., China): an external add-on camera mechanically locked to the scanner with a latch-on USB port that allows for HD scanning. At the beginning of each measurement session the scanner was calibrated following the manufacturer’s instructions and using the etched glass board provided with the scanner. All scans were completed in hand-held HD Scan mode, without markers (“features mode”), setting a resolution of 0.5mm, at 20 frames per second, with 1 million points collected per second. A metrological scanner was used as a reference and assumed as ground truth: the EINScan Laser FreeScan X5 (SHINING 3D Tech. Co. Ltd., China).

Four distinct limb shapes were selected from a digital database of over 1000 sockets from one of the clinical sites:
A. Transfemoral socket for a long residual limb, with ischial containment producing undercuts/indentations around the proximal brim, referred to as “TF Ischial”;
B. Transfemoral socket for a long residual limb, with ischial containment but no undercuts/indentations around the proximal brim. Since this socket was based on hydrostatic casting with the Symphonie Aqua system (Romedis GmbH, Germany), it will be referred to as “TF Aqua”;
C. Transtibial socket for a mid-length residual limb, with a total surface bearing design and a cylindrical shape, referred to as “TT Cylindrical”;
D. Transtibial socket for a long residual limb, with patellar tendon bearing design and a conical shape, referred to as “TT Conical”.

Once selected, the four limb models were carved from polyurethane foam by a robot (Ortis, Fabrica Machinale, Caschina, PI, Italy). This material was chosen because it is lightweight and less fragile than plaster casts and less likely to be damaged during shipping to different sites. To prevent the limb models from deteriorating due to impact or abrasion, they were covered in polyethylene terephthalate glycol (PETG) by vacuum forming, starting from a 0.12mm sheet. The PETG surface was then sanded and sprayed with matte paint. Finally, 7mm holes were drilled in the extension above the proximal socket trim lines to serve as technical landmarks to align (i.e., spatially register) the scanned shapes during data analysis.

Three sites participated in the assessments, two in the United States (USA1 and USA2) and one in Europe (EU). Each site had its own structured-light scanner (same model). Two individuals participated at each site: Operator 1 (OP1) with experience using the scanner, and Operator 2 (OP2) with minimal prior experience using the scanner. The same four limb models were mailed to each site. At each site, OP1 scanned the four limb models twice (OP1-A and OP1-B) with the structured-light scanner, and OP2 scanned the four limb models once with the same scanner, for a total of 12 scans per site. At the European site an additional reference scan of each positive model (4 scans) was conducted by an independent professional Operator (OP0) using the metrological scanner (EINScan Laser FreeScan 5X). 

For each model, scans were processed as follows. First, the EINScan software was used to remove background surfaces and geometries and to generate watertight meshes in STL file format. Then, the obtained digital meshes were processed, using custom Python software, which takes advantage of Meshlab and Visual Toolkit (VTK) libraries as computational geometry engines, with Qt to support the graphical user interface. To decrease computational costs, all seven scans from each limb model were decimated to 30%, i.e. removing 70% of mesh vertices, to obtain meshes of reduced dimension in PLY file format.