backend/download_models.py

#!/usr/bin/env python3
"""
Download Depth-Anything V2 ONNX models from HuggingFace

This script downloads optimized ONNX versions of Depth-Anything V2 models
for fast inference without PyTorch dependency.
"""

import os
from pathlib import Path
from huggingface_hub import hf_hub_download
import sys


# Model configurations
MODELS = {
    "small": {
        "repo_id": "depth-anything/Depth-Anything-V2-Small",
        "filename": "depth_anything_v2_vits.onnx",
        "size": "~100MB",
        "speed": "Fast (25M params)"
    },
    "large": {
        "repo_id": "depth-anything/Depth-Anything-V2-Large",
        "filename": "depth_anything_v2_vitl.onnx",
        "size": "~5GB",
        "speed": "Slower (1.3B params)"
    }
}


def download_model(model_type: str, cache_dir: str = "./models/cache"):
    """
    Download a Depth-Anything V2 ONNX model

    Args:
        model_type: Either 'small' or 'large'
        cache_dir: Directory to cache models
    """
    if model_type not in MODELS:
        print(f"❌ Error: Unknown model type '{model_type}'")
        print(f"Available models: {', '.join(MODELS.keys())}")
        return False

    model_info = MODELS[model_type]
    cache_path = Path(cache_dir)
    cache_path.mkdir(parents=True, exist_ok=True)

    print(f"\n📥 Downloading {model_type} model...")
    print(f"   Repo: {model_info['repo_id']}")
    print(f"   File: {model_info['filename']}")
    print(f"   Size: {model_info['size']}")
    print(f"   Speed: {model_info['speed']}")

    try:
        # Note: Using a placeholder repo since actual ONNX models might not be available
        # In production, you would either:
        # 1. Convert PyTorch models to ONNX yourself
        # 2. Use a community ONNX conversion
        # 3. Host your own converted models

        print("\n⚠️  IMPORTANT NOTE:")
        print("Official ONNX models may not be available on HuggingFace yet.")
        print("You'll need to convert PyTorch models to ONNX format.")
        print("\nTo convert models yourself:")
        print("1. Install: pip install torch transformers")
        print("2. Download PyTorch model")
        print("3. Export to ONNX using torch.onnx.export()")
        print("\nAlternatively, check these resources:")
        print("- https://github.com/LiheYoung/Depth-Anything")
        print("- Community ONNX conversions on HuggingFace")

        # Placeholder for actual download
        # model_path = hf_hub_download(
        #     repo_id=model_info['repo_id'],
        #     filename=model_info['filename'],
        #     cache_dir=str(cache_path)
        # )

        print(f"\n✓ Model would be saved to: {cache_path / model_info['filename']}")
        return True

    except Exception as e:
        print(f"\n❌ Error downloading model: {e}")
        return False


def create_conversion_script():
    """Create a helper script for converting PyTorch to ONNX"""

    script_content = '''#!/usr/bin/env python3
"""
Convert Depth-Anything V2 PyTorch model to ONNX
"""

import torch
from transformers import AutoModel
import sys

def convert_to_onnx(model_name, output_path):
    """Convert model to ONNX format"""

    print(f"Loading PyTorch model: {model_name}")
    model = AutoModel.from_pretrained(model_name, trust_remote_code=True)
    model.eval()

    # Dummy input
    dummy_input = torch.randn(1, 3, 518, 518)

    print(f"Exporting to ONNX: {output_path}")
    torch.onnx.export(
        model,
        dummy_input,
        output_path,
        input_names=['input'],
        output_names=['output'],
        dynamic_axes={
            'input': {0: 'batch', 2: 'height', 3: 'width'},
            'output': {0: 'batch', 2: 'height', 3: 'width'}
        },
        opset_version=17
    )

    print(f"✓ Conversion complete: {output_path}")

if __name__ == "__main__":
    # Example usage
    convert_to_onnx(
        "LiheYoung/depth-anything-small-hf",
        "depth_anything_v2_vits.onnx"
    )
'''

    script_path = Path("convert_to_onnx.py")
    script_path.write_text(script_content)
    script_path.chmod(0o755)

    print(f"\n✓ Created conversion script: {script_path}")
    print("  Run with: python convert_to_onnx.py")


def main():
    """Main download function"""

    print("=" * 60)
    print("Depth-Anything V2 Model Downloader")
    print("=" * 60)

    # Create models directory
    models_dir = Path("./models/cache")
    models_dir.mkdir(parents=True, exist_ok=True)

    # Download models based on command line args
    models_to_download = sys.argv[1:] if len(sys.argv) > 1 else ['small']

    if 'all' in models_to_download:
        models_to_download = list(MODELS.keys())

    for model_type in models_to_download:
        download_model(model_type)

    # Create conversion helper
    print("\n" + "=" * 60)
    create_conversion_script()

    print("\n" + "=" * 60)
    print("Next Steps:")
    print("=" * 60)
    print("1. Convert PyTorch models to ONNX (see convert_to_onnx.py)")
    print("2. Place ONNX models in ./models/cache/")
    print("3. Update .env with correct model paths")
    print("4. Start the server: uvicorn api.main:app --reload")
    print("=" * 60)


if __name__ == "__main__":
    main()