Add tqdm progress bar for fragment loading

[tanmay-srivastav4]

Summary

While exploring the reconstruction pipeline, I noticed that fragment loading provides no visual feedback during processing. This PR adds a progress bar to improve user experience and provide real-time status updates during long-running fragment loads.

Key Changes

• Progress Visualization: Added tqdm progress bar to the fragment loading loop in load_and_process_fragments() method
• Real-time Feedback: Users now see:
  • Current file being processed
  • Progress percentage and file count (e.g., 2/10)
  • Elapsed time and estimated time remaining
  • Processing speed (files/second)
• Improved Error Messages: Enhanced error message clarity when no valid PLY files can be loaded

Verification

• Tested with multiple fragment sets (3, 5, and 10 PLY files)
• Verified progress bar updates correctly in real-time
• Confirmed error handling works for:
  • Empty directories (no PLY files found)
  • Corrupted/invalid PLY files (files exist but can't be loaded)

Example Output:

Loading fragments from: data/input
Loading fragments: 100%|███████████████| 3/3 [01:23<00:00, 27.8s/file]

Dependencies

• Added: tqdm>=4.65.0 to requirements.txt

Notes

I'm exploring opportunities to improve the pipeline's user experience.This change is intentionally minimal and focused, but the same pattern could be applied to other long-running operations (feature extraction, surface matching, alignment) if this approach looks good.

Happy to contribute more based on feedback!