Optical Metrology & Point Clouds // Protocol PCD-01
Point Cloud Density & Sampling Calculator
Calculate surface point cloud density (pts/mm²), spatial point pitch (µm), scanning duration, and polygon triangle budgets for reverse engineering and inspection.
0.120 m²
50 µm (0.050 mm)
20 µm (Fine Metrology)100 µm (Standard CAD)500 µm (Large Castings)
50%
Polygon reduction for CAD import
Point Cloud & Mesh Metrics
Surface Point Cloud Density
400pts / mm²
40.0k pts/cm² · Pitch: 50 µm
Total Point Count
96.00 M pts
96,000,000 raw pts
Sweep Duration
1.2 min
Pure optical capture
Uncompressed .PLY / .XYZ:2.86 GB
Compressed .E57 / .LAZ:549 MB
Decimated STL Triangle Mesh:96.00M triangles (4578 MB)
VDI/VDE 2634 Sampling Protocols
The Physics of Spatial Sampling Density & Polygon Budgets
1. Nyquist Sampling of Mechanical Features
To digitize a mechanical fillet or internal radius of curvature $R$ accurately, metrology guidelines require at least 5 to 7 point samples along the arc:
Pitch_max ≤ (2 · π · R · θ) / 360° · (1 / 6)
For a 1.0 mm sheet metal bend radius, point pitch must be 50 µm or finer (400 pts/mm²). Insufficient point density produces polygon faceting that fails GD&T profile-of-a-surface inspections.
2. Decimation & Curvature-Adaptive Meshing
Uniform high-density point clouds swamp CAD engines (SolidWorks, CATIA, NX) when files exceed 10 million polygons:
- Planar Decimation: Flat planar surfaces can be thinned by 80% without losing geometric integrity.
- Curvature Retention: Ensure non-uniform rational B-spline (NURBS) reverse engineering tools preserve raw point density around parting lines, knife edges, and hole boundaries.