Self-Supervised Monocular Depth

Self-supervised monocular depth estimation is the training approach that learns single-image depth prediction from unlabeled stereo pairs or monocular video using photometric consistency losses - it delivers practical depth models without dense ground-truth annotations.

What Is Self-Supervised Monocular Depth?

• Definition: Depth network trained by reconstructing one view from another through predicted disparity or depth.
• Training Data: Stereo pairs, monocular sequences, or mixed setups.
• Inference Mode: Single-image depth prediction at deployment.
• Scale Behavior: Metric scale can be learned with known stereo baseline during training.

Why It Matters

• Annotation-Free Learning: Eliminates need for expensive lidar-labeled datasets.
• Scalable Pretraining: Uses large video corpora across domains.
• Practical Deployment: Produces lightweight monocular depth predictors for edge devices.
• Domain Transfer: Easier adaptation through self-supervised fine-tuning.
• SLAM Support: Provides useful priors for visual odometry and mapping.

Training Recipe

Photometric Reconstruction:
- Warp source view to target using predicted depth and relative pose.
- Minimize pixel and structural similarity losses.

Regularization Terms:
- Edge-aware smoothness to reduce depth noise.
- Occlusion masking and auto-masking for dynamic regions.

Multi-Scale Supervision:
- Depth outputs at several scales improve optimization stability.
- Coarse-to-fine refinement improves detail.

How It Works

Step 1:
- Predict depth map and relative pose from unlabeled image pairs or sequences.

Step 2:
- Reconstruct target view through differentiable warping and optimize consistency losses.

Self-supervised monocular depth is a scalable route to practical depth perception that learns from geometric consistency rather than manual labels - it is a core technique for modern low-cost 3D vision systems.