System and method for measuring scene reflectance using optical sensors

• US 20070268481A1
• Filed: 05/17/2006
• Published: 11/22/2007
• Est. Priority Date: 05/17/2006
• Status: Abandoned Application

• Current Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Inventors: Zhao, Yong, Raskar, Ramesh, Dietz, Paul H., Nii, Hideaki, Bruns, Erich
• Application Number:
  US11/435,581
• Publication Number:
  US 20070268481A1
• Time in Patent Office: Days
• US Class Current: 356/218
• CPC Class Codes: G01J 1/42 using electric radiation detectors optical or mechanical part G01J1/04; by comparison with a reference light or electric value G01J1/10
• CPC Class Codes: G01N 2021/557 Detecting specular reflective parts on sample
• CPC Class Codes: G01N 21/55 Specular reflectivity
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/30204 Marker
• CPC Class Codes: G06T 7/73 using feature-based methods

Abstract

A system measures reflectance in a scene. A first optical sensor is configured to measure incident energy at a location in a scene. A second optical sensor is configured to measure reflected energy from the location in the scene. The incident energy and the reflected energy are analyzed to determine a photometric property at the location of the scene.

Claims

1. A system for measuring reflectance at a location in a scene, comprising:

a first optical sensor configured to measure incident energy at a location in a scene;

a second optical sensor configured to measure reflected energy from the location in the scene; and

means for analyzing the incident energy and the reflected energy to determine a photometric property at the location in the scene.

2. The system of claim 1, in which the photometric property includes incident illumination at the location.

3. The system of claim 1, in which the photometric property includes reflected radiance at the location.

4. The system of claim 1, in which the photometric property includes a bidirectional reflectance distribution function at the location.

5. The system of claim 1, in which the photometric property includes a parameterization selected from the group consisting of wavelength, amplitude, phase, polarization, phospherence, fluorescence, angle and combinations thereof.

6. The system of claim 1, in which the first optical sensor is a photo diode, and the second sensor is a camera.

7. The system of claim 1, further comprising:

means for comparing the incident energy and the reflected energy to determine a reflectance at the location.

8. The system of claim 1, in which the first optical sensor is a photo diode emitting an electronic signal corresponding to the incident energy, and the second optical sensor is a camera acquiring an image including pixels having intensity values.

9. The system of claim 8, in which the intensity value of a particular pixel corresponding to the location is divided by the electronic signal to determine a reflectance at the location.

10. The system of claim 8, further comprising:

means for setting parameters of the camera using the incident energy.

11. The system of claim 8, in which the reflected energy is compared to the incident energy to determine parameters for the camera.

12. The system of claim 11, in which the camera parameters are selected from the group consisting of exposure, focus, aperture, gain, white balance, color filters, polarization filters, anti-blooming, anti-ghosting, and combinations thereof.

13. The system of claim 1, further comprising:

means for factorizing the reflected energy into illumination and reflectance components of photometric properties of the scene.

14. The system of claim 1, in which the first photo sensor is embedded in an optical tag including a microcontroller and a memory configured to store the measured incident energy.

15. The system of claim 14, in which the optical tag further comprises:

a wireless transceiver configured to communicate the measured incident energy stored in the memory.

16. The system of claim 15, in which the measured incident energy is communicated to a base station.

17. The system of claim 9, in which the electronic signal is multiplied by a color transform function.

18. A method for measuring reflectance in a scene, comprising:

measuring incident energy at a location in a scene using a first optical sensor;

measuring reflected energy from the location in the scene using a second optical sensor; and

analyzing the incident energy and the reflected energy to determine a photometric property of the scene at the location.

19. The method of claim 18, in which the photometric property includes reflected radiance at the location.

20. The method of claim 18, in which the first optical sensor is a photo diode emitting an electronic signal corresponding to the incident energy, and the second optical sensor is a camera acquiring an image including pixels having intensity values, and further comprising:

dividing an intensity value of a particular pixel corresponding to the location by the electronic signal to determine a reflectance at the location.

21. The method of claim 18, in which the first optical sensor is a photodiode and the second optical sensor is a camera and further comprising:

setting parameters of the camera using the incident energy and the reflected energy.