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3D scanning: the basics for makers

3D scanning5 min readUpdated: 10/2026

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A 3D scanner captures the shape of a real object and turns it into a digital 3D model. Many devices also record colour. For makers this is mainly interesting when a part is to be reprinted, adapted or processed further digitally: a broken bracket, a figure, a face for a bust.

You will find all the scanners in the wiki with technology, accuracy and price in the overview of 3D scanners.

What happens during scanning

The scanner measures a very large number of points on the surface of the object. Together they form a point cloud. The software connects the points into a network of triangles, the mesh. This is the actual 3D model. If the scanner has a colour camera, the software additionally lays a texture over the mesh, meaning the colour of the surface.

A scanner only sees what it illuminates and captures with its camera. For a complete model you therefore need many individual captures from different directions. The software assembles them. For this to work, it relies on the shape of the object, on its surface structure or on markers stuck onto it. What it has never seen, such as the underside, remains a gap.

File formats

  • STL stores only the shape as triangles, no colour and no unit. It is the standard format for 3D printing.
  • OBJ stores shape and texture coordinates. The colours are in an additional MTL file with an image.
  • PLY can store colour directly at every point and is suitable for point clouds and coloured meshes.

The common scanning programs export all three formats.

What makers scan for

  • Spare parts and reverse engineering: capturing an existing part to reprint it or to use as a basis for your own design.
  • Figures, sculptures and art: digitising objects, scaling them down or up, or printing them as a replica.
  • People: scanning a face, torso or whole person, for example for a bust. Handheld scanners are suitable for this because they are fast enough if someone does not keep completely still.
  • Parts that fit exactly: designing a holder around an existing object, for example for a tool or a device.

Limits

  • Dark, shiny and transparent surfaces are difficult. Dark ones swallow the light, shiny ones throw it back uncontrollably, transparent ones let it through. Depending on the technology, a scanning spray helps.
  • Movement distorts the scan, because the points are captured at different times.
  • Fine details below the scanner’s point spacing are lost, even if it is otherwise very accurate.
  • Deep recesses and undercuts are often out of the scanner’s reach. Holes remain there, which the software can only estimate.

From scan to print

The scanner delivers a model at real size. Before it goes into the slicer, you usually tidy it up: remove stray points, close holes, reduce the triangle count. How this works is covered under From scan to print. Which technology suits which use is explained in the article Scanning technologies compared, and a decision aid for buying can be found under Which 3D scanner is right?.

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