This project focuses on the processing and interpretation of Ground Penetrating Radar (GPR) data acquired from a concrete wall in a basement car box. The primary objective was to process 15 parallel vertical profiles to detect and visualize the reinforcement rebars structure. The project moves from raw data analysis to a full 3D cube representation, enabling a clear view of the rebar layout within the wall.
The dataset consists of 15 parallel vertical profiles collected with the following specifications:
| Parameter | Value |
|---|---|
| Nominal Frequency | 3 GHz |
| Polarization | HH |
| TX-RX Distance | 6 cm |
| Profile Inter-distance | 10 cm |
| Trace Increment | 4 mm |
| Total Traces | 6752 |
The data was processed using Reflexw software through the following pipeline:
- Phase Correction: We applied the "correct max. phase" operation two times to align all profiles effectively.
- Time Calibration: The start time was moved by -0.9 ns to calibrate the zero-time surface reflection.
To improve the signal-to-noise ratio:
- Bandpass Butterworth Filter: Applied to isolate the most energetic region of the spectrum (Lower Cutoff: 650 MHz, Upper Cutoff: 4030 MHz).
- Background Subtraction: A subtracting average procedure (window: 250 traces) was used to remove background noise and horizontal ringing.
- Velocity Analysis: By fitting diffraction hyperbolas, the propagation velocity was estimated at 0.135 m/ns.
- Migration (Diffraction Stack): This step collapsed the diffraction hyperbolas to correctly position the targets. A summation width of 50 was calculated based on the hyperbola aperture (~0.2m).
- Envelope Extraction: Calculated to visualize signal energy strength.
- 3D Modeling: A 3D cube was generated to view the rebar grid in volumetric space.
- Rebar Spacing: The analysis revealed a clear grid with rebars spaced approximately 0.2 m (20 cm) apart.
- Target Depth: The reinforcement bars are located at a depth of approximatel 5 cm.
- Structure: The 3D view highlighted that the rebars are not perfectly straight, indicating variations during the construction phase.