COSBOS: COlor-Sensor-Based Occupancy Sensing

COSBOS is a high-performance MATLAB/Octave toolbox for occupancy sensing using color sensors. It implements advanced Light Transport Matrix (LTM) recovery techniques and occupancy models, optimized for speed and reliability.

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Table of Contents

• Project Overview
• Installation and Setup
• Key Features
• Modules
  • LTM Recovery
  • Blockage Model
  • Reflection Model
• Running Demos
• Unit Testing
• Python Package
  • Installation
  • Usage
  • Development
• Citation

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Project Overview

Color sensors can be used as low-cost, privacy-preserving alternatives to cameras for occupancy sensing. By measuring changes in the Light Transport Matrix (LTM) of a room, we can infer the presence and location of occupants. COSBOS provides the tools to:

1. Recover the LTM from sensor measurements, both overdetermined and underdetermined. This work is described in [2].
2. Model occupancy using light blockage (for wall-mounted sensors). This work is described in [1] and [3].
3. Model occupancy using light reflection (for ceiling-mounted sensors). This work is described in [1].

More information:

• [4] is not directly related to this package. It is about the new color sensors that we have built for occupancy sensing.
• In each demo, we included example data. But the code for data collection has too many dependencies: platform, hardware, driver, and other software packages. Thus we are not including the code for data collection here.
• More information on this work can be found here:
  • https://sites.google.com/site/cosboswiki/
• This library is also available at MathWorks:
  • https://www.mathworks.com/matlabcentral/fileexchange/48428-cosbos-color-sensor-based-occupancy-sensing

Installation and Setup

1. Clone the repository: git clone https://github.com/wq2012/COSBOS.git
2. Ensure you have MATLAB or Octave installed.
3. If using the Blockage Model, you need to compile the C++ MEX files:
   • Go to BlockageModel/ and run compile.m in MATLAB/Octave.
   • Requires a C++ compiler (e.g., GCC, Clang, or MSVC).

Key Features

• High Performance: Vectorized computations and optimized C++ MEX implementations.
• Robust Modularity: Module-specific configuration files (e.g., coordinates_blockage.m) to prevent name collisions.
• Absolute Path Support: All demos and tests are designed to run from any directory without path issues.
• Clean Output: Silenced runtime warnings and polished logs.

Modules

LTM Recovery

Located in LTM_Recovery/. Solves $Y = AX$ for the mapping $A$.

• solve_A_fullrank.m: Standard pseudo-inverse solution.
• solve_A_Fnorm.m: Stable low-rank approximation via SVD.
• solve_A_0norm.m: Sparse recovery using Orthogonal Matching Pursuit (OMP).
• solve_A_1norm.m: Sparse recovery using primal-dual interior point methods.

Blockage Model

Located in BlockageModel/. For wall-mounted sensors.

• Uses coordinates_blockage.m for spatial configuration.
• hashGaussians.cpp: Optimized MEX code for distance hashing (no heap allocation in hot loops).
• volumeFromHashing.cpp: Fast volume rendering via optimized internal matrix management.

Reflection Model

Located in ReflectionModel/. For ceiling-mounted sensors.

• Uses coordinates_reflection.m for spatial configuration.
• getReflectionKernel.m: Fully vectorized implementation for near-instant kernel generation.

Running Demos

Each module includes a robust demo script:

• LTM_Recovery/demo_LTM.m: Demonstrates LTM recovery techniques.
• BlockageModel/demo_Blockage.m: Renders a 3D occupancy volume.
• ReflectionModel/demo_Reflection.m: Generates a floor-plane occupancy map.

Unit Testing

Run the master test script from the project root:

addpath('tests');
run_tests;

This verifies LTM recovery accuracy, MEX script correctness, and model performance.

Python Package

COSBOS is also available as a Python package cosbos. It provides pure Python implementations of the core algorithms (Reflection Model, Blockage Model, LTM Recovery).

Installation

pip install cosbos

Usage

from cosbos import reflection, blockage, ltm
import numpy as np

# Reflection Model
# Calculate reflection kernel for a light-sensor pair
# light: [x, y, z], sensor: [x, y, z], dim: [dx, dy, dz]
K = reflection.getReflectionKernel(light=[75, 22.5, 86.4], 
                                   sensor=[66, 22, 86.4], 
                                   dim=[87, 136, 88], 
                                   para=1)

# Blockage Model
# Hash Gaussians for occupancy volume
# sensors: [N, 3], lights: [M, 3]
H = blockage.hashGaussians(sensors, lights, dim, sigma=2.0)
# Reconstruct volume
V = blockage.volumeFromHashing(sensors, lights, dim, H, E)

# LTM Recovery
# Recover matrix A from measurements Y and training data X
# X: [m, N], Y: [l, N] (m: features, l: sensors, N: samples)
A = ltm.solve_A_1norm(X, Y)

Development

To run tests locally:

cd python
pip install -e .
pytest tests/

Citation

If you use this work in your research, please cite:

Plain Text:

[1] Quan Wang, Xinchi Zhang, Kim L. Boyer, "Occupancy distribution estimation for smart light delivery with perturbation-modulated light sensing", Journal of Solid State Lighting 2014 1:17, ISSN 2196-1107, doi:10.1186/s40539-014-0017-2.

[2] Quan Wang, Xinchi Zhang, Meng Wang, Kim L. Boyer, "Learning Room Occupancy Patterns from Sparsely Recovered Light Transport Models", 22nd International Conference on Pattern Recognition (ICPR), 2014.

[3] Quan Wang, Xinchi Zhang, Kim L. Boyer, "3D Scene Estimation with Perturbation-Modulated Light and Distributed Sensors", 10th IEEE Workshop on Perception Beyond the Visible Spectrum (PBVS).

[4] Xinchi Zhang, Quan Wang, Kim L. Boyer, "Illumination Adaptation with Rapid-Response Color Sensors", SPIE Optical Engineering + Applications, 2014.

[5] Quan Wang. Exploiting Geometric and Spatial Constraints for Vision and Lighting Applications. Ph.D. dissertation, Rensselaer Polytechnic Institute, 2014.

BibTeX:

@article{wang2014occupancy,
  title={Occupancy distribution estimation for smart light delivery with perturbation-modulated light sensing},
  author={Wang, Quan and Zhang, Xinchi and Boyer, Kim L},
  journal={Journal of solid state lighting},
  volume={1},
  number={1},
  pages={17},
  year={2014},
  publisher={Springer}
}

@inproceedings{wang2014learning,
  title={Learning room occupancy patterns from sparsely recovered light transport models},
  author={Wang, Quan and Zhang, Xinchi and Wang, Meng and Boyer, Kim L},
  booktitle={2014 22nd International Conference on Pattern Recognition},
  pages={1987--1992},
  year={2014},
  organization={IEEE}
}

@inproceedings{wang20143d,
  title={3d scene estimation with perturbation-modulated light and distributed sensors},
  author={Wang, Quan and Zhang, Xinchi and Boyer, Kim L},
  booktitle={Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition Workshops},
  pages={252--257},
  year={2014}
}

@inproceedings{zhang2014illumination,
  title={Illumination adaptation with rapid-response color sensors},
  author={Zhang, Xinchi and Wang, Quan and Boyer, Kim L},
  booktitle={Optics and Photonics for Information Processing VIII},
  volume={9216},
  pages={49--60},
  year={2014},
  organization={SPIE}
}

@phdthesis{wang2014exploiting,
  title={Exploiting Geometric and Spatial Constraints for Vision and Lighting Applications},
  author={Quan Wang},
  year={2014},
  school={Rensselaer Polytechnic Institute},
}