CAP Viewer

CAP Viewer is a custom viewer built on top of aitviewer for reviewing SMPLX animations with synchronized foot pressure and EMG signal videos.

Features

• 3D SMPLX Animation: Main view displays SMPLX 3D model sequence
• Foot Pressure Video: Floating panel showing synchronized foot pressure video
• EMG Signal Video: Floating panel showing synchronized EMG signal video
• Frame Synchronization: All views are automatically synchronized to the same frame index
• Interactive Controls:
  • Drag panels to reposition them
  • Use Playback panel to control animation
  • Video frames update automatically when sliding the progress bar

Layout

The viewer uses a floating panel layout:

• Main window: Full 3D SMPLX animation view
• Floating panels: Foot Pressure and EMG videos (can be dragged and resized)

Usage

Basic Usage

from capviewer import CapViewer

viewer = CapViewer(
    smplx_path="path/to/smplx_animation.npz",
    foot_pressure_path="path/to/foot_pressure.mp4",  # Optional
    emg_path="path/to/emg_signal.mp4"  # Optional
)

viewer.run_animations = True
viewer.playback_fps = 30.0
viewer.run()

Command Line Usage

# With SMPLX only
python capviewer/capviewer.py path/to/smplx_animation.npz

# With SMPLX and foot pressure video
python capviewer/capviewer.py path/to/smplx_animation.npz --foot-pressure path/to/foot_pressure.mp4

# With SMPLX, foot pressure, and EMG videos
python capviewer/capviewer.py path/to/smplx_animation.npz --foot-pressure path/to/foot_pressure.mp4 --emg path/to/emg_signal.mp4

Test Script

# Run test script (will try to find .npz files automatically)
python capviewer/test_capviewer.py

Requirements

• aitviewer
• opencv-python (cv2)
• numpy
• imgui (included with aitviewer)

Frame Synchronization

The viewer automatically maps SMPLX frame indices to video frame indices using linear interpolation:

• If SMPLX has N frames and video has M frames:
  • Frame 0 of SMPLX → Frame 0 of video
  • Frame N-1 of SMPLX → Frame M-1 of video
  • Intermediate frames are linearly interpolated

This ensures smooth synchronization even if the frame counts differ.

Panel Controls

• Reposition: Click and drag the panel title bar
• Resize: Drag the edges/corners of the panel
• Close/Show: Click the X button or use the visibility toggle
• Frame Info: Each panel shows current frame numbers for both SMPLX and video

Notes

• Video files are optional - the viewer will work with just SMPLX animation
• Video frames are cached for performance (up to 100 frames)
• The viewer automatically handles different frame counts between SMPLX and videos
• All panels are synchronized to the Playback control in the main viewer