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Phase 4: Environmental Reconstruction (Geospatial)

WORKFLOWADVANCED
📖10 min read

Introduction​

Environmental reconstruction focuses on rebuilding the geospatial context of the scene. This phase establishes the "Ground Truth"—the accurate, real-world stage upon which the investigation plays out.

Geolocation

Verify coordinates and establish a relative origin.

Acquisition

Import vector data, elevation models, and satellite imagery.

Verification

Ensure CRS consistency and align with Ground Control Points.

Geolocation​

Verify coordinates. If no location is found, proceed with Relative Reconstruction (arbitrary origin).

Chronolocation: Determine the time of day and date to accurately simulate lighting conditions (sun position).

Terrain & Context Acquisition​

Vector Data: Import OSM (OpenStreetMap) footprints via QGIS.

Elevation: Import DEM (Digital Elevation Models) for accurate terrain topography.

Photorealistic Context:

  • Satellite: Google/Bing Satellite imagery (Regular and possibly Historical/Dated).
  • 3D Tiles: Import Photogrammetry Mesh (Google Earth 3D) or Geometry Rip (via RenderDoc).

Critical Check: When using BlenderGIS ensure CRS (Coordinate Reference System) consistency across all datasets.

Coordinate System Verification​

  • Document CRS: Explicitly state which CRS you're using (e.g., WGS84, UTM Zone X).
  • Resolution standards: Specify minimum acceptable resolution for satellite imagery (e.g., "prefer 1m/pixel for urban scenes").
  • Temporal matching: If your event happened in 2023 but Google Earth imagery is from 2019, document what changed (construction, demolished buildings).
  • Vertical datum: Clarify whether elevation is relative to sea level (EGM96, EGM2008) or ellipsoid.

Ground Control Points (GCPs)​

  • Identify Landmarks: Find fixed landmarks visible in both your evidence AND satellite/maps (corners of buildings, painted road markings).
  • Anchor Points: These become your "anchor points" for aligning everything.
  • Documentation: Document GCP coordinates in a table with confidence ratings.

Summary​

A solid environmental reconstruction ensures that your scene is geographically accurate. By integrating vector data, elevation models, and satellite imagery within a consistent coordinate system, you create a reliable base for placing evidence and testing hypotheses.

Key Takeaways:

  • CRS Consistency: Ensure all data layers use the same Coordinate Reference System.
  • Temporal Awareness: Be aware of the date of your satellite imagery vs. the event date.
  • Ground Control: Use GCPs to lock your reconstruction to the real world.

Documentation for Methodology​

What to document during Environmental Reconstruction

In Your Method Section​

"The environment was reconstructed using [CRS Name] as the coordinate reference system. Terrain data was derived from [DEM Source] with a resolution of [X] meters. Vector data for building footprints was imported from OpenStreetMap and verified against satellite imagery dated [Date]."

In Your Decision Log​

Record the following:

  • The specific CRS code (e.g., EPSG:32633).
  • The source and date of satellite imagery used.
  • Any discrepancies found between map data and visual evidence (e.g., "Satellite image shows a building that is not present in the video evidence; confirmed demolition date via news source").
  • Coordinates of Ground Control Points used for alignment.

Verification​

"The alignment of the 3D terrain model was verified by checking the position of [Landmark A] and [Landmark B] against their known GPS coordinates."

Further Resources:

Last updated on by blender-visual-investigation