I spent two days last year scanning a sandstone frieze on a 140-year-old building in Sydney’s Rocks district. The carving was deteriorating—decades of salt air and pollution had softened details that were originally crisp. Within a generation, the finer elements would be gone entirely.

Ten years ago, documentation would have meant photographs, maybe some silicone moulds, and hand-drawn measurements. Today, a structured light scanner captured the entire frieze at sub-millimetre resolution. Every chisel mark, every eroded edge is preserved as a digital 3D model that will outlast the stone itself.

How the Scanning Works

Several technologies capture 3D surface data from stone carvings. Structured light scanning projects patterns onto the surface and reads distortion to calculate geometry. Photogrammetry uses overlapping photographs processed through software. LiDAR provides point cloud data at longer ranges.

For detailed documentation, structured light delivers the best resolution—current portable scanners capture detail down to about 0.05mm, fine enough to record individual tool marks. That means you’re not just recording a carving’s shape; you’re recording how it was made.

Photogrammetry is more accessible for larger installations where absolute precision matters less. A competent photographer with good software can produce serviceable 3D models without specialised scanning equipment. The practical challenge outdoors is environmental—direct sunlight confuses scanning systems, wind vibrates equipment, and most of my work happens early morning or on overcast days.

Preservation Through Documentation

The most immediate value is creating a permanent, precise record. Stone deteriorates—that’s not a possibility, it’s a certainty. Every carved surface is losing detail right now through weathering, pollution, or physical damage.

The Australian Heritage Council has funded scanning programs for significant sandstone buildings in Sydney and Brisbane. Sydney’s Hawkesbury sandstone is particularly vulnerable—relatively soft, it weathers noticeably within decades. Some carved details on buildings from the 1850s have already lost most of their original crispness.

Having a precise 3D record means future conservators can understand what the original looked like even after significant degradation. You can also track deterioration rates by comparing scans taken years apart.

Replication and Restoration

This is where scanning intersects directly with my work. When a damaged carving needs restoration, a 3D scan provides reference that’s far more useful than photographs or drawings.

For hand carving, I use 3D prints of scanned originals as bench references. Having the exact form sitting beside me while I carve is invaluable—I can measure depths, check profiles, and verify proportions at any point. It’s fundamentally better than working from photographs where perspective distortion misleads you about actual geometry.

CNC routing from scan data is also used for replication, particularly where multiple identical pieces are needed. The machine does bulk removal to within a few millimetres, and a carver finishes by hand. Purists argue this isn’t true restoration, but I think that’s a false boundary. The original carvers used whatever tools gave them the best results.

The team at a consultancy we rate has been doing interesting work on the software side, particularly around processing large scan datasets for conservation documentation and carving reference. The intersection of traditional craft and digital technology is producing better outcomes than either approach alone.

Challenges and Limitations

Scanning captures surface geometry brilliantly but misses internal structure—fractures, moisture content, and mineral composition all affect conservation decisions but remain invisible. Colour capture is improving but still imperfect, since stone colour changes with moisture, lighting angle, and surface finish.

File sizes for detailed architectural scans are enormous. A single facade at full resolution can produce terabytes of data, requiring infrastructure that not all heritage organisations have budgeted for.

What It Means for Stone Carvers

I see 3D scanning as a tool that expands what’s possible rather than replacing traditional skills. For working carvers, scanning is becoming part of the professional toolkit alongside chisel technique and stone selection. I invested in a portable scanner two years ago, and it’s paid for itself through documentation contracts and improved accuracy in restoration work.

The craft of carving stone hasn’t changed—you still need to understand the material, read its grain, and develop hand skills that only come through practice. But the tools we use to document, plan, and reference our work have improved dramatically. That’s not a threat to tradition. It’s an extension of it.