Results & Validation¶
Research results and validation. All values match the submitted manuscript (Computers and Electronics in Agriculture).
Reconstruction Quality Metrics (Condition 1, 5 fps, Jan 19)¶
| Metric | Value | Interpretation |
|---|---|---|
| PSNR | 23.71 dB | Good (>20 dB acceptable) |
| SSIM | 0.773 | Good (1.0 = perfect) |
| LPIPS | 0.222 | Good (0.0 = perfect) |
| PSNR temporal CV | 3.5% | Excellent consistency across 22 sessions |
| Mean PSNR (22 sessions) | 23.84 dB | All sessions exceed 22.5 dB |
Plant Trait Monitoring Results (cross-session consistency)¶
Why CV is the right metric
This is a monitoring system: the goal is to track relative change over time, not to report absolute, calibrated trait values. The coefficient of variation (CV, lower = more consistent) is therefore the primary and appropriate evaluation metric.
| Metric | Proposed (render-space) | Baseline (direct PLY) | Improvement |
|---|---|---|---|
| h_norm CV | 9.8% | 28.0% | 2.86× more stable |
| a_norm CV | 16.7% | 22.6% (PLY spread) | More stable |
| Scale-calibrated PLY CV | — | 35.1% | Worse than direct PLY |
Biological Validation — Pruning-Event Detection¶
The render-space signal detects real crop-management events, which is the key evidence that it tracks biology rather than noise.
| Aspect | Result |
|---|---|
| Documented pruning events detected | 3 / 3 |
| Mean drop at pruning | ≈ 0.20 normalized height (15–27 pp) |
| Significance (pruning vs. non-pruning dates) | p = 0.0008 |
| Background variation | 9.8% (CV) — drops are well above it |
Physical-Reference Validation — 45 cm Pipe¶
Render-space height is corroborated against an in-scene 45 cm bench pipe used as a ruler, h_gt = (plant_px / pipe_px) × 45 cm, annotated across all 22 sessions.
| Aspect | Result |
|---|---|
| Correlation (render-space vs. pipe reference) | r = 0.74, p < 0.001 |
| R² | 0.55 |
| Reference mean height | 159.9 cm |
| Spread | h_gt CV 8.9% vs. h_norm CV 9.6% |
Corroboration, not accuracy
r = 0.74 shows the signal is grounded in real-world scale — it is not a claim of absolute-height accuracy. The ~45% unexplained variance is noise in the pipe reference itself (SfM scale ambiguity across sessions), not pipeline error.
Plant Growth Time-Lapse¶
3DGS-rendered plant growth across all 22 acquisition dates (Jan 19 – Mar 9, 2026). Each frame shows the height measured from the rendered canonical image.
Validation Results¶
- Dates: 22 capture dates
- Duration: 49 days (Jan 19 – Mar 9, 2026)
- Success Rate: 100% (22/22)
- Computing: DNN19, RTX 6000 Ada
Key Finding¶
Fixed viewpoint (Condition 1, 5 fps) outperforms all other acquisition conditions:
| Condition | PSNR |
|---|---|
| Cond. 1 — Fixed end-a, lower viewpoint | 23.71 dB |
| Cond. 5 — One-way a→d, tier 1 | 21.42 dB |
| Cond. 2 — Fixed end-b, lower viewpoint | 20.11 dB |
| Cond. 3 — Round-trip, tier 1 | 19.37 dB |
| Merged (all 6 combined) | 18.60 dB |
Lesson: Acquisition consistency > method sophistication
Limitations and Future Ground Truth¶
Honest limitations
- No calibrated ground truth (RMSE): these 22 sessions have no tape-measured physical heights, so the system is validated for consistency (CV) and change detection, not absolute accuracy. The 45 cm-pipe result is corroboration, not calibration.
- Reference-instrument noise: the pipe reference carries its own SfM scale ambiguity (pipe spans 263–420 px for a fixed 45 cm), which accounts for most of the unexplained variance in the r = 0.74 agreement.
- Operator not blinded to the pruning schedule; events were confirmed from work logs post-hoc.
Planned ground-truth protocol (future work)
A three-tier protocol would upgrade the evaluation from consistency to absolute accuracy:
- Tape measurements on 5–10 tagged plants per session (direct RMSE).
- Rigid calibration bar of known length in-scene — removes the dominant variance source of a movable pipe.
- ArUco markers for a full per-session similarity transform → absolute metric units.