Point Cloud
Definition
The raw data product of a LiDAR survey: a set of 3D coordinates (X, Y, Z) for each laser return, classified by return type (ground, low vegetation, medium vegetation, building, etc.).
- Data source
- Laser scanners or LiDAR systems
- Core components
- X, Y, Z coordinates; color and intensity values
- Data format
- Raw coordinates before reconstruction or processing
Common questions
What exactly is a point cloud in crime scene documentation?+
A point cloud is a 3D dataset created by laser scanners that captures millions of coordinates (X, Y, Z positions) for every surface in a scene. It's the raw data output before any reconstruction or processing, often with color and intensity information attached to each point.
How does LiDAR produce a point cloud?+
A LiDAR system fires laser pulses and records where each return comes from. Every return generates a 3D coordinate. The system then classifies what each return hit: ground, vegetation, buildings, or other objects. This classification helps forensic teams understand the scene structure.
Why use point clouds instead of photographs at a crime scene?+
Point clouds capture precise 3D geometry and measurements across an entire space, not just what the camera lens sees. They preserve the full spatial relationship between objects and can be rotated and analyzed from any angle in the lab, making reconstruction and distance calculations much more reliable.
Related terms
- 3D Laser Scanner
- An instrument that emits a laser sweep across the scene and records millions of distance measurements per second, producing a point-cloud model...
- Bare-Earth DTM
- A digital terrain model produced by filtering LiDAR returns to ground-level pulses only, removing vegetation and structure returns. The resulting surface represents...
- BNSS Section 105 Videography
- The mandatory continuous video recording of search and seizure under the Bharatiya Nagarik Suraksha Sanhita 2023.
- Drone Overhead Capture
- Aerial photography or videography from an unmanned aerial vehicle, used for outdoor scenes that exceed ground-level photographic coverage.
- Evidence-Grade Digital Imaging
- Capture and storage of digital images in a manner that preserves chain-of-custody integrity, typically through hash-based fingerprinting of the original RAW or...
- Ground Classification
- The algorithmic process (e.g., using LAStools or PDAL) that separates ground-surface returns from non-ground returns in a LiDAR point cloud, enabling bare-earth...
- LiDAR
- Light Detection and Ranging: an active remote-sensing method that emits laser pulses and records the time-of-flight of returning echoes to produce a...
- Micro-Topography
- Small-scale (centimetre to metre) variations in ground surface height. Grave mounding, subsidence hollows, and soil-scrape scars are micro-topographic features typically invisible to...
- SfM Point Cloud
- A 3D point cloud derived from overlapping photographs using Structure from Motion photogrammetry. Achieves similar resolution to terrestrial LiDAR at close range...
Explained in these topics
- Digital Imaging, 3D Scanning and Crime Scene VideographyThe 3D dataset produced by a laser scanner, consisting of millions of XYZ coordinates with associated colour and intensity values. The raw output before any re...
- LiDAR and Topographic SurveyThe raw data product of a LiDAR survey: a set of 3D coordinates (X, Y, Z) for each laser return, classified by return type (ground, low vegetation, medium vege...