• Ekstrand, L., Zhang, S., Grieve, T., Chumbley, L. S., & Kreiser, M. J. (2014).

62a1⁝ Research Note - Physically Based Simulation of Surface Micro-Geometry Analysis of Contact Mechanics, Elastoplastic Deformation, and Rendering Algorithms

Some notes

Kilka rzeczy do wzięcia pod uwagę aby generowanie było rzeczywistą symulacją

  1. Contact mechanics + plastic deformation (depth, groove width, pile‑up, contact patch shape)
  2. Microscopic striation modeling (edge micro‑geometry, wear, chatter, serration pitch)
  3. Surface topography synthesis (anisotropic roughness, brushed/grain direction, stochastic pits)
  4. Multi‑pass and tool slip (overshoot, stick‑slip, acceleration profile)
  • [x]
    1. Physics: Elastic Springback & Strain Hardening
    • What is missing: Currently, the simulation is purely plastic (permanent deformation). In reality, metals are elastic-plastic. After the tool passes, the material “springs back” slightly (Elastic Recovery), making the groove shallower and tighter than the tool itself.
    • Improvement: Implement a Springback Factor based on Young’s Modulus.
    • Strain Hardening: As you drag, the metal ahead of the tool should get harder (work hardening), increasing resistance and changing the pile-up shape dynamically.

  1. Complex Trajectories & Variable Mechanics
  • What is missing: Real tool marks are rarely perfect straight lines with constant force.
  • Improvement:
    • Bezier/Freehand Paths: Allow curved scratches (e.g., wrist rotation).
    • Variable Profiles: Force and Angle should change during the cut (e.g., a “scooping” motion where the tool dives deep and then lifts off).
    • Tool Roll: Using the corner of a flathead screwdriver (30° roll) creates a completely different, V-shaped asymmetric trace.
  1. Forensic Visualization (The “CSI” View)
  • What is missing: Real examiners don’t just look at a gray 3D mesh. They use specific lighting and color modes to find matches.
  • Improvement:
    • Raking Light Control: A light source you can move to 0-5° elevation to exaggerate shadows and reveal faint striations.
    • Depth Map (False Color): Render the surface as a heat map (Blue = Deep, Red = High) for precise depth analysis.
    • Normal Map Mode: Visualizing surface slope changes to remove color distractions.
  • 5. Material Fracture & Chip Formation
    • What is missing: Currently, we “displace” material. We don’t “tear” it.
    • Improvement: For brittle materials or sharp knives, we should simulate Chip Detachment (where material is actually removed/curled off, not just pushed aside) and Fracture (cracks radiating from a crowbar impact).

62 Forensic