Measuring in 3D: Structure Dimensions and Distances Between Layers

· 5 min read · AcademicAR Team

A kidney in a bounding box and the closest distance to a vessel

“How big is it?” and “How close is it to that?” are among the first questions a reader asks about a 3D structure. In a static figure the answer is a number in the caption. In AcademicAR, layered models carry their own measurements, so readers can see the numbers in context.

What is measured

When a model has multiple layers — structures from a segmentation, presets from a CT, or parts of a CAD assembly — the worker computes, for each layer:

  • Oriented dimensions: the three edge lengths of the tightest box around the structure, aligned with the structure itself rather than the scanner axes. This gives a meaningful length, width, and depth even for an oblique organ.
  • Maximum diameter: the largest distance between any two points of the structure — the familiar “longest axis” measure.

And between structures:

  • Minimum distance between neighbouring layers, with the two closest points marked in the viewer. Pairs further than about 5 cm apart are skipped, so the list stays focused on relationships that matter.

Values are reported in millimetres, computed from the full-resolution geometry before compression. Layer measurements are included in the paid model plans (pricing).

Oriented dimensions and maximum diameter of one layer, and the minimum distance between two layers What is measured per layer and between neighbouring layers.

Why this matters in medicine

  • Tumour-to-vessel distance is central to resectability discussions; showing it on an interactive model makes the spatial relationship obvious.
  • Organ and lesion dimensions support case reports and teaching cases.
  • Anatomical variation studies can present the measured structure and the number together.

And in engineering and the sciences

  • Clearances in assemblies: the minimum distance between two parts is a clearance check readers can inspect.
  • Morphometrics in biology, palaeontology, and archaeology: oriented dimensions and maximum diameter are standard descriptors of specimens.

You stay in control

Measurements depend on the model’s scale, so check units after upload; if you rescale the model, its measurements are recomputed. The owner can also hide the measurements from public viewers — useful when numbers are preliminary or when the model is meant for orientation rather than quantification.

For precise point-to-point checks at a specific level, combine these with the snapping measure in the slice view.

Publish a layered model and let readers see the numbers in 3D.