Good scan data starts before the scanner is switched on. The single most reliable way to improve 3D scanning outcomes is thorough object preparation — addressing surface issues, environmental factors, and fixturing in advance rather than trying to recover from them in post-processing. The extra time spent preparing an object can save multiples of that time in cleanup and rework.
Here’s a practical guide to preparing objects for 3D scanning, covering the most common challenges and how to handle them.
Assess the Surface Before You Scan Anything
Look at the object and ask: how will a scanner’s light interact with this surface? That single question surfaces most preparation needs before they become problems in the data.
Problematic surface types include:
- Highly reflective or mirror-finish surfaces — Polished stainless steel, chrome, machined aluminum, glossy paint. These scatter or mirror light back at unpredictable angles, creating data gaps and noise.
- Transparent or translucent materials — Glass, clear acrylic, polycarbonate, resin castings. Light passes through rather than reflecting back, causing the scanner to return nothing useful from those areas.
- Matte black or very dark surfaces — Absorb light instead of reflecting it, resulting in weak or missing data in dark regions.
- Highly textured or porous surfaces — Can cause fine-scale noise in the point cloud, though these are usually manageable without special treatment.
Using Temporary Scanning Spray
The standard solution for reflective, transparent, and dark surfaces is temporary matte scanning spray — a fine, even coat that gives the surface consistent, controlled reflectivity. Key points:
- Apply an even, thin coat from a consistent distance — typically 20–30cm. Thick or uneven application can add measurable surface buildup that introduces dimensional error.
- Allow the spray to dry fully before scanning. Wet or tacky spray changes its optical properties.
- Most scanning sprays wash off with water or a light solvent. Test on a non-critical area first if you’re unsure about compatibility with the surface finish.
- For precision metrology work, be aware that even very thin spray layers add a small amount to measured dimensions. Document this if working to tight tolerances.
Fixturing: Keeping the Object Stationary
Any movement during scanning introduces error — usually manifesting as blurry or doubled geometry in areas affected by the shift. Objects should be secured before scanning begins and must not be touched or disturbed until all required scan passes from a given position are complete.
Practical fixturing approaches:
- Non-slip mat or foam underneath for stable placement without clamping marks
- Purpose-built fixtures or V-blocks for cylindrical or precision parts
- Sandbags or wedges for irregular shapes that don’t sit stably on their own
- Rotary turntables for all-around capture of smaller objects — the object stays fixed while the scanner or camera positions change
If you need to reposition the object between scan passes, do so deliberately — noting what coverage was already captured and ensuring the new position is stable before continuing.
Adding Reference Targets
Many structured light and laser scanning systems use reference targets — small adhesive dots placed on or around the object — to help the software align consecutive scan passes. They give the scanner fixed known points to register each pass against, which improves alignment accuracy across complex objects or multi-pass setups.
Place targets:
- On the object itself, in areas that will appear in multiple scan passes
- On the surface the object rests on (table, fixture, or background board)
- In a non-uniform distribution — random spacing aligns better than evenly spaced grids
- Away from edges and critical features where they might obstruct the geometry you need to capture
Clean the Object
Dust, debris, grease, and oils affect both the surface appearance and how light reflects. For precision engineering scans, a clean surface is a baseline requirement. Wipe down the object before scanning — use appropriate cleaning methods for the material to avoid scratching or leaving residue.
Think Through Coverage Before You Start
Before the first scan pass, mentally map out which surfaces need to be captured and how many passes from which angles will be required to cover them all. Plan for deep recesses, undercuts, and enclosed areas — and be realistic about what a standard optical scanner simply cannot reach. Knowing those limitations upfront prevents wasted passes and missed areas that are difficult to re-capture after the setup is disassembled.
At Kemperle Industries, preparation is built into every scanning project we take on. Complex surfaces — from reflective automotive finishes to ornate historic plasterwork — require a tailored approach to each job. If you’re preparing an object for scanning and want to talk through the right approach, get in touch.
