Phase 1 - Ingestion & Processing
Introduction​
The first phase of geometric reconstruction focuses on ordering and analyzing source media streams to extract technical data and convert raw footage into usable assets. This foundation is critical for the accuracy of the entire project.
CRITICAL: Never alter original source files. All manipulations (sharpening, un-distorting) must be done on duplicates/proxies. Log every filter & setting applied for transparency.
Ingest
Securely archive and hash all source material.
Analysis
Assess optics, artifacts, and metadata.
Processing
Enhance images and align footage temporally.
Source Intelligence (Analysis)​
Ingest​
Collect all Video, Photos and other source material.
Master Archive:
- Create a (protected) directory (e.g.,
/00_Master_Archive). - Save all sources here exactly as received/downloaded.
Fingerprinting (Hashing):
- Generate a Checksum (SHA-256) for all files (See Hashing)
- Store the Source Name, Download Date, Download location, Hash in a spreadsheet/text file (See Bellingcat best practices)
Create working_file directory
- Copy all source material here.
Segmentation​
If one video contains multiple clips, create separate clips.
Naming:
- Create Directories for each video
- Extract Frames from each Video
Source Grouping: Sort and group files by physical device (e.g., "Source A - CCTV North," "Source B - Witness iPhone").
/01_WORKING_COPIES
/00_MASTER_INGEST
[Project]_Master_Compilation_Copy.mov <-- The big file you copied
/01_SOURCES <-- The result of your "Chop"
/SRC_A_CCTV_North
/Footage <-- The segmented video clip (ProRes/DNxHR)
/Image_Seq <-- The full PNG/EXR sequence extracted from footage
/Stills <-- Specific keyframes picked for reference
/Work <-- Undistorted/Sharpened versions
/SRC_B_Mobile_Witness
/Footage
/Image_Seq
/Stills
/Work
Technical Assessment (See Camera Fundamentals for Investigation)​
Optics: Analyze footage for Lens Distortion types (Barrel, Pincushion, Mustache) and Vignetting per main source file.
Artifacts: Identify Motion Artifacts (Motion Blur, Rolling Shutter, Compression blocks).
Geometry: Identify sources with optimal Perspective Lines (One-point, Two-point, or Three-point) to determine the best solving method for each specific angle.
Check for Metadata / Metadata Extraction (See Metadata Extraction)​
Action: Analyze file headers (EXIF/XMP) for each main source file (look at the main video, not the videos derived from it)
Key Data: Look for Camera Make/Model, Focal Length, Sensor Size, Date/Time, and GPS coordinates.
Note: If source is from social media, metadata is likely stripped; rely on visual "Technical Assessment."
If no metadata: Estimate if each specific camera uses a Prime Lens (Fixed) or Zoom Lens (Variable focal length). Estimate the Focal Length for Fixed Lens (Wide angle shots, zoomed shots), Possible Sensor Width (mm) for each profile independently.
Temporal Alignment (See video alignment)​
Sync all video footage to a single master real-world timeline (e.g., "Event Time 12:00:00") using metadata timestamps or visual anchors (e.g., a specific flash of light visible in all cameras).
Further Processing​
Image Enhancement (Working Copies):
Create separate "Work Files" for selected images. See if lens distortion can be countered, reduce blur (sharpening), upscale, or adjust contrast to reveal stronger perspective lines.
Summary​
In this phase, we have established a secure and organized foundation for the investigation. By strictly separating master archives from working copies and systematically analyzing the technical properties of each source, we ensure that all subsequent reconstruction steps are built on verified data.
Key Takeaways:
- Preservation: Always keep a pristine, hashed copy of original evidence.
- Organization: Use a consistent folder structure and naming convention.
- Analysis: Understand the technical limitations (distortion, artifacts) of your footage before modeling.
- Alignment: Sync multiple sources to a single timeline early in the process.
Documentation for Methodology​
What to document during Ingestion & Processing
In Your Method Section​
Describe the chain of custody for your digital assets. "All source material was hashed (SHA-256) upon receipt and stored in a read-only master archive. Working copies were generated for analysis. Metadata was extracted using [Tool Name] to establish camera parameters."
In Your Decision Log​
Record the following:
- Hash values of original files.
- Any enhancements applied to working copies (e.g., "Applied unsharp mask to Frame 405 to read license plate").
- Estimated camera parameters when metadata was missing.
- Synchronization points used for temporal alignment.
Verification​
"Checksums of working copies were verified against the master archive log to ensure data integrity."
Further Resources: