# Caption Quality Test for Cross-View Geo-Localization

Validate whether generated text captions improve retrieval R@1 in cross-view
geo-localization (drone-to-satellite).

## Architecture

### Overview

Asymmetric dual-encoder with domain-specific frozen backbones and hierarchical
text fusion for drone-to-satellite image retrieval.

```
┌──────────────────────────── QUERY BRANCH ────────────────────────────┐
│                                                                       │
│  drone_img ──► DINOv3 ViT-L/16 LVD ──► CLS token                    │
│  [B,3,256,256]   (frozen, 303M)         d_img [B,1024]               │
│                                            │                          │
│  L1 (overview)    ──► DGTRS-CLIP ──► z₁ [B,768] ─┐                   │
│  L2 (full desc)   ──► DGTRS-CLIP ──► z₂ [B,768] ─┼─ cat ──► [B,2304]│
│  L3 (fingerprint) ──► DGTRS-CLIP ──► z₃ [B,768] ─┘    │             │
│      (248 tokens, KPS pos. emb.)          MLP(2304→1024→1024)        │
│                                                 │                     │
│                                            d_txt [B,1024]            │
│                                                 │                     │
│           q = σ(α_q)·d_img + (1−σ(α_q))·d_txt   GatedFusion_q      │
│                          │                                            │
│                    q̂ = q / ‖q‖₂  ──► query [B,1024]                  │
└───────────────────────────────────────────────────────────────────────┘

┌──────────────────────────── GALLERY BRANCH ──────────────────────────┐
│                                                                       │
│  sat_img ──► DINOv3 ViT-L/16 SAT ──► CLS token                      │
│  [B,3,256,256]  (frozen, 303M)        s_img [B,1024]                 │
│                                          │                            │
│  sat_L1 ──► DGTRS-CLIP ──► z₁ [768] ─┐                               │
│  sat_L2 ──► DGTRS-CLIP ──► z₂ [768] ─┼─ cat ──► MLP ──► s_txt [1024]│
│  sat_L3 ──► DGTRS-CLIP ──► z₃ [768] ─┘      (shared MLP)            │
│                                          │                            │
│       g = σ(α_g)·s_img + (1−σ(α_g))·s_txt   GatedFusion_g           │
│                                          │                            │
│                                   ĝ = g / ‖g‖₂  ──► gallery [B,1024]│
└───────────────────────────────────────────────────────────────────────┘

Retrieval space: 1024-dim (DINOv3 native, no projection layers)
TextFusionMLP shared between query and gallery branches
For sat images without captions: s_txt=None → g = s_img (gate passthrough)

BASELINE: σ(α) = 1.0 for both branches (text disabled, DGTRS not loaded)
```

### Text hierarchy (L1 / L2 / L3)

Each drone image has a VLM-generated caption (Qwen3-VL) split into 3 levels:

| Level | Name | Content | Typical length |
|-------|------|---------|----------------|
| **L1** | Overview | First sentence of P1: land-cover summary with class percentages | 15–30 tokens |
| **L2** | Full description | Complete P1 (inventory) + P2 (spatial layout with 5+ zones) | 100–200 tokens |
| **L3** | Fingerprint | P3: unique landmarks and spatial signature for matching | 20–50 tokens |

All three levels are encoded by a **single DGTRS-CLIP ViT-L-14** text encoder
(248-token context via KPS positional embedding, 768-dim output).

**Text fusion (shared MLP for both branches):**

```
z_text = MLP( [z₁ ; z₂ ; z₃] )

where [z₁ ; z₂ ; z₃] ∈ ℝ^(B×2304)  — concatenation of three 768-dim embeddings
      MLP: Linear(2304, 1024) → GELU → Linear(1024, 1024)
      z_text ∈ ℝ^(B×1024)
```

**Gated fusion (separate gates for query and gallery):**

```
q = σ(α_q) · d_img + (1 − σ(α_q)) · d_txt     (query branch)
g = σ(α_g) · s_img + (1 − σ(α_g)) · s_txt     (gallery branch)

where α_q, α_g — separate learnable scalars in logit-space (init: σ(α) ≈ 0.7)
      σ — sigmoid function
      d_img, s_img — DINOv3 image embeddings [B, 1024]
      d_txt, s_txt — fused text embeddings [B, 1024]

For satellite images without captions: s_txt = None → g = s_img
```

### Loss function

Symmetric InfoNCE with learnable temperature (CLIP-style `logit_scale`):

```
L = w_q2g · L_q→g + w_g2q · L_g→q

L_q→g = CrossEntropy( q̂ · ĝᵀ / τ,  targets )
L_g→q = CrossEntropy( ĝ · q̂ᵀ / τ,  targets )

where τ = 1 / exp(logit_scale),  logit_scale — learnable scalar
      τ ∈ [0.01, 0.5]  (clamped)
      τ_init = 0.07
      w_q2g = 0.6,  w_g2q = 0.4
      targets = [0, 1, 2, ..., B−1]  (positives on diagonal)
      label_smoothing = 0.1
```

Loss is computed in **fp32** (outside AMP autocast) to prevent gradient overflow
in the learnable temperature.

### Metrics

| Metric | Formula | Direction |
|--------|---------|-----------|
| **R@K** (Recall at K) | fraction of queries where correct gallery is in top-K | drone → satellite (primary) |
| **Delta R@1** | R@1(with_text) − R@1(baseline) | higher = text helps |

Reported: R@1, R@5, R@10 for both q→g and g→q directions.

### Optimizer & scheduler

```
Optimizer: AdamW
  - TextFusionMLP, gate α_q, gate α_g, logit_scale:
      lr = 1e-4,  weight_decay = 1e-4
  - DGTRS text encoder (last resblock + ln_final + text_projection):
      lr = 1e-5  (10× lower, --text-lr-factor 0.1)

Scheduler: Linear warmup (2 epochs) + cosine annealing
  - Per-step (not per-epoch)
  - warmup: lr linearly ramps from 0 to lr_max over warmup_steps
  - cosine: lr decays from lr_max to 0 over remaining steps

Gradient clipping: max_norm = 1.0
Mixed precision: AMP fp16 for model forward, fp32 for loss
```

### Augmentations

| Transform | Drone (train) | Satellite (train) | Eval |
|-----------|:---:|:---:|:---:|
| RandomResizedCrop(256, scale=0.7–1.0) | ✓ | ✓ | — |
| Resize(256) + CenterCrop(256) | — | — | ✓ |
| RandomHorizontalFlip(0.5) | ✓ | ✓ | — |
| RandomRotation(15°) | ✓ | — | — |
| ColorJitter(0.3, 0.3, 0.2, 0.1) | ✓ | ✓ | — |
| RandomGrayscale(0.05) | ✓ | ✓ | — |
| GaussianBlur(k=3, σ=0.1–2.0) | ✓ | — | — |
| ImageNet Normalize | ✓ | ✓ | ✓ |

### Model summary

| Component | Params | Trainable | Notes |
|-----------|--------|-----------|-------|
| DINOv3 ViT-L/16 LVD (drone) | 303M | 0 | frozen |
| DINOv3 ViT-L/16 SAT (satellite) | 303M | 0 | frozen |
| DGTRS-CLIP ViT-L-14 (text) | 124M | ~7.6M | last block + ln_final + text_projection |
| TextFusionMLP (shared) | 3.5M | 3.5M | Linear(2304,1024) + GELU + Linear(1024,1024) |
| GatedFusion α_q | 1 | 1 | query gate scalar |
| GatedFusion α_g | 1 | 1 | gallery gate scalar |
| logit_scale | 1 | 1 | learnable temperature |
| **Total** | **734M** | **11.1M (1.51%)** | retrieval dim = 1024 |

## Experiments

### V3 — GTA-UAV + DINOv3 + DGTRS-CLIP (active)

**Dataset:** GTA-UAV-LR (33K drone + 14K satellite, GTA V synthetic)
- RGB: `/home/servml/Документы/datasets/GTA-UAV-LR/`
- Captions: `/home/servml/Документы/datasets/GTA-UAV-LR-captions/` (40K JSON, 3-paragraph VLM)
- Segmentation: `/home/servml/Документы/datasets/GTA-UAV-LR-aug/` (17 classes)
- Seg filter: 37,498 passed / 10,905 excluded (>=90% background+water)
- Split: 80/20 random (26,966 train / 6,742 test → 24,891/6,252 after seg filter)

### V2 — UAV-GeoLoc + GeoRSCLIP (legacy)

Single backbone with template captions.

```
Query:   drone_img + caption -> GeoRSCLIP -> GatedFusion -> query
Gallery: sat_img -> GeoRSCLIP -> gallery
```

**Dataset:** UAV-GeoLoc Terrain split (206K train queries)

## Structure

```
caption-test/
├── conf/                         # Gin configs (v2)
│   ├── balanced.gin
│   ├── baseline_no_text.gin
│   └── text_heavy.gin
├── nn_models/                    # Pre-trained checkpoints (v3, gitignored)
│   ├── DINO_WEB/                 # DINOv3 ViT-L/16 LVD-1689M (.pth)
│   ├── DINO_SAT/                 # DINOv3 ViT-L/16 SAT-493M (.safetensors)
│   └── LRSCLIP/                  # DGTRS-CLIP ViT-L-14 (.pt)
├── meta/                         # Generated metadata
│   ├── train_80.json             # 80% train split (26,966 pairs)
│   ├── test_20.json              # 20% test split (6,742 pairs)
│   └── seg_filter.json           # Segmentation filter results
├── scripts/
│   ├── make_split.py             # Create 80/20 train/test split
│   ├── filter_segmentation.py    # Exclude 90%+ background/water images
│   ├── compare_runs.py           # Delta R@1 comparison report
│   └── generate_captions.py      # Offline caption generation
├── src/
│   ├── datasets/
│   │   ├── gtauav_dataset.py     # GTA-UAV-LR loader + L1/L2/L3 parsing (v3)
│   │   └── visloc_with_captions.py  # UAV-GeoLoc loader (v2)
│   ├── models/
│   │   ├── dgtrs/                # Official DGTRS-CLIP text encoder (Apache-2.0)
│   │   │   ├── model.py          # DGTRSTextEncoder, build_model, tokenize
│   │   │   ├── simple_tokenizer.py  # BPE tokenizer (248 tokens)
│   │   │   └── bpe_simple_vocab_16e6.txt.gz
│   │   ├── asymmetric_encoder.py # DINOv3 + DGTRS + GatedFusion (v3)
│   │   └── dual_encoder.py       # GeoRSCLIP + GatedFusion (v2)
│   ├── losses/
│   │   └── multi_infonce.py      # InfoNCE with learnable temperature
│   ├── training/
│   │   ├── train_gtauav.py       # Training loop GTA-UAV (v3)
│   │   └── train.py              # Training loop UAV-GeoLoc (v2)
│   └── eval/
│       └── evaluate.py           # R@K metrics, Delta R@1
└── checkpoints/                  # GeoRSCLIP RS5M_ViT-B-32.pt (v2)
```

## Prerequisites

```
torch>=2.0
safetensors
coloredlogs
tqdm
ftfy
regex
gin-config
Pillow
numpy
```

## Workflow (V3 — GTA-UAV)

### 1. Create 80/20 split and filter segmentation

```bash
python -m scripts.make_split --output-dir meta
python -m scripts.filter_segmentation --output meta/seg_filter.json
```

### 2. Train baseline (no text)

```bash
python -m src.training.train_gtauav --baseline --filter-meta meta/seg_filter.json
```

### 3. Train with captions (L1/L2/L3)

```bash
python -m src.training.train_gtauav --filter-meta meta/seg_filter.json
```

### 4. Resume from checkpoint

```bash
python -m src.training.train_gtauav --resume out/gtauav/with_text/ckpt_epoch004.pt \
    --filter-meta meta/seg_filter.json
```

### 5. Compare and get verdict

```bash
python -m scripts.compare_runs \
    --baseline_report out/gtauav/baseline/eval_report.json \
    --full_report out/gtauav/with_text/eval_report.json \
    --output out/gtauav/comparison.md
```

## Decision rule

| Delta R@1 (drone→satellite) | Verdict |
|---|---|
| >= +3% | **PASS** — captions informative, proceed to NADEZHDA teacher |
| +1% to +3% | MARGINAL — add VLM refinement, re-run |
| 0 to +1% | WEAK — redesign caption pipeline |
| < 0 | HARMFUL — critical bug |

## Code style

- `from __future__ import annotations` everywhere
- Type hints on all signatures
- Google-style docstrings
- English-only comments