Cultural heritage CAD documentation with computer vision

Conservation offices, restorers and heritage consultants work on protected assets where every intervention has to be documented graphically before, during and after the works. The drawing is not a by-product of the survey: it is the object the authority reviews, the base on which decay is mapped and the reference against which the finished intervention is checked. Producing it by tracing contours over photographs is slow, and the cost falls entirely on the professional's time.

CVCAD vectorises photoplans and orthophotos of historic facades, frescoed surfaces, mosaics, stucco apparatus, cornices, bas-reliefs and sculpture, returning a base drawing for condition mapping and restoration design in SVG and DXF.

Extraction is driven by tonal and material transitions rather than by architectural assumptions, so it performs on painted plaster, gilding, mosaic tesserae, modelled stucco and stone weathering as well as on masonry elevations. On modelled elements — capitals, bas-reliefs, sculpted profiles — raking light sharpens the boundary between planes and measurably improves the definition of the extracted profiles.

In practice this produces the layers a conservation report needs: outlines of colour fields and lacunae, detachment and blistering perimeters, crack patterns, joints and mortar courses, and the silhouette of plastic elements for template and repetition studies.

Calibration uses two points of known length — a survey target, a levelling rod, a dimension measured on site — and the file is regenerated server-side in real millimetre scale. Nothing is rescaled after download, so geometric integrity is preserved and the DXF opens without import errors.

Generated drawings belong to the user, with no restriction on professional or public-tender use: as-built elevations, decay mapping bases, technical attachments for authorisation procedures, and bases for quantity take-off and structural assessment. Uploaded files stay in a private per-user store for five days, are served through expiring signed links and are then permanently deleted — which matters when the commission itself is confidential.