Digital images, laser scans, photogrammetry and video record different aspects of a scene. Select and validate the method for the required detail, geometry and uncertainty rather than assume newer equipment records everything.
Preserve original data, processing history and control measurements. A model or hash is useful evidence about its defined task, not proof of a complete scene, an event’s truth or legal compliance.
By the end of this topic you will be able to:
- Compare imaging, scanning and video tasks.
- Check measurement accuracy and coverage.
- Preserve data provenance and processing history.
- Evidence-grade digital imaging
- Documented capture, preservation and processing suited to the evidential task; no file-format label alone guarantees quality.
- 3D laser scanner
- An instrument sampling visible surfaces through measured range and direction, with instrument-dependent capability.
- Point cloud
- A set of spatial samples, sometimes with intensity or colour attributes; hidden regions remain unmeasured.
- Drone overhead capture
- Aerial recording subject to aviation, safety and privacy requirements.
- BNSS section 105 videography
- An Indian statutory recording provision with a specific scope, not a universal continuous-scene-film specification.
Digital Imaging: Originals, Derivatives and Provenance
Standard digital photography produces JPEG, RAW, or DNG files on a memory card. Evidence-grade digital imaging adds two things: the capture process is documented end-to-end, and the original file is hash-fingerprinted at the earliest possible moment so any later modification is detectable.
A documented workflow can include the following, according to the equipment and task:
- Retain original captured files; RAW can be useful but is not a universal admissibility requirement.
- Make controlled backups and record integrity checks.
- Identify reference hashes and intentionally different derivatives.
- Control access and retain processing and migration records.
A mismatch establishes that the compared bytes differ. It does not by itself prove malicious tampering; confirm that the intended files and versions were compared.
3D Laser Scanning at Scene
Laser scanning produces spatial samples from measured range and direction. Colour and intensity availability, sampling and accuracy depend on the instrument and settings.
Plan enough stations, suitable control and registration checks for the task. There is no universal setup time, station count or guarantee that every surface is captured.
What 3D scanning is good for:
- Record visible sampled geometry and derive measurements with stated uncertainty.
- Retain registration and control checks.
- Use clearly explained visualisations without filling missing regions as if measured.
What it's not good for:
- Capturing fine detail. Point density at the surface is too low for fingerprint or trace work; macro photography still owns that scale.
- Small or hidden evidence. The scanner sees what's visible from its setup position; an item under furniture or inside a drawer needs to be moved into view before scanning.
- Quick deployment. The hardware is bulky, the setup takes time, and the scan can't begin until the scene is fully secured.
Check actual instrument capabilities and service availability. Unsupported lists of national deployments are not evidence of the suitability of a particular scan.
Drone Overhead Capture
Aerial capture can provide useful context and mapping where lawful and safe. Aviation permissions and operator requirements are jurisdiction-specific.
Standard drone uses at scene:
- Choose viewpoint and altitude for lawful safe operation and required detail.
- Use suitable overlap and control for photogrammetry.
- Check orthomosaic or 3D product accuracy independently; a stitched picture alone is not a measurement guarantee.
Check the relevant aviation authority, airspace, privacy and scene-safety requirements. Do not assume a standard altitude, police exemption or universal operator model.
BNSS Section 105 Videography
India’s BNSS section 105 addresses specified audio-video recording and forwarding duties within its scope. It is not a universal scanner, camera or hashing specification.
Retain original recordings, explain interruptions and derivatives, and record relevant integrity checks and access.
Operational details depend on the actual service and governing rules. Verify the applicable recording, retention and forwarding instructions.
How the Three Techniques Fit Together
Coordinate complementary methods around the required questions, access and available resources.
- Scans record sampled geometry; photographs can record selected surface detail.
- Video records a changing view or process.
- Specialist spectral capture answers additional optical questions.
Parallel work can help, but it may also introduce access conflicts or extra processing. Do not claim a measured national reduction in scene-release time without a dataset.
Check Your Understanding
Sources
- 1.Photographic Equipment and Infrastructure Recommendations · SWGDE
- 2.Image Processing Guidelines · SWGDE
- 3.Best Practices for the Forensic Use of Photogrammetry · SWGDE
- 4.Research on scene laser-scan presentation · National Institute of Justice