Moving object detection using a digital read-out integrated circuit and degree of polarization and angle of polarization at the pixel level

Patent metadata

Field	Value
Publication number	US-11195285-B2
Application number	US-202016837390-A
Country	US
Kind code	B2
Filing date	Apr 1, 2020
Priority date	Apr 1, 2020
Publication date	Dec 7, 2021
Grant date	Dec 7, 2021

Abstract

An object detection system comprises a polarizer configured to polarize an incoming image scene, a motor controller configured to control a spin rate of the polarizer, a lens configured to collect scene data from the polarized image scene, a first integrated circuit configured to measure the collected scene data at two different and orthogonal polarizations, a second integrated circuit configured to determine a degree of polarization (DoP) and an angle of polarization (AoP) for each image frame pair and to generate pre-processed data, and a processor configured to match the pre-processed data to target criteria. The first integrated circuit can be a DROIC imager and the second integrated circuit can be a FPGA. The AoP and DoP can be determined at a pixel level. The second integrated circuit is configured to apply spatial filtering having a DoP greater than 70% or where AoP is unique to immediate surroundings of AoP.

First claim

What is claimed:

1. An object detection system comprising:
a polarizer configured to polarize an incoming image scene, and to generate a polarized image scene;
a motor controller configured to control a spin rate of the polarizer;
a lens configured to collect scene data from the polarized image scene, the scene data including a plurality of image frames;
a digital read-out integrated circuit (DROIC) imager configured to measure the scene data collected from the polarized image scene such that each image frame pair of the scene data collected from the polarized image scene is collected at two different and orthogonal polarizations;
a field-programmable gate array (FPGA) configured to determine a degree of polarization (DoP) and an angle of polarization (AoP) for each image frame pair, to apply spatial filtering to the DoP and AoP for each image frame pair, and to generate pre-processed data as a result of the spatial filtering; and
a processor configured to match target criteria using the pre-processed data received from the FPGA,
wherein the FPGA is configured to:
determine the DoP by processing at least two image frame pairs of the plurality of image frames; and
determine the AoP for the at least two frame pairs based on the position of the polarizer received at the FPGA from the motor controller, and

wherein processing the at least two image frame pairs comprises adding a first frame of the first image frame pair to a first frame of the second image frame pair and subtracting a first frame of the first image frame pair from a second frame of the second image frame pair, the second image frame being consecutive with respect to the first image frame.

2. The object detection system of claim 1 , wherein the second integrated circuit is integral with the processor.

3. The object detection system of claim 1 , wherein the AoP and DoP are determined at a pixel level such that each pixel is analyzed.

4. The object detection system of claim 1 , wherein the polarizer is delayed by 180-degrees of rotation by the motor controller to determine the AoP.

5. The object detection system of claim 1 , wherein the polarizer is rotated by 360-degrees by the motor controller for each 0.5 seconds of search performed by the first integrated circuit.

6. The object detection system of claim 1 , wherein the spatial filter is searching for targets having the DoP greater than 70%.

7. The object detection system of claim 1 , wherein the first integrated circuit uses an image processing construct using cluster filters for contrast on each frame for 1-by-1-pixel clusters or 2-by-2-pixel clusters.

8. The object detection system of claim 1 , wherein a shift in the AoP and the DoP measurement will indicate the level of target detection confidence.

9. A method comprising:
spinning a polarizer, by a motor controller, at a rate that is slightly out of phase with respect to an image frame rate of a digital read-out integrated circuit (DROIC) imager;
acquiring a plurality of image frame pairs by the DROIC imager, each image frame pair having a first image frame and a second image frame;
determining a degree of polarization (DoP) and an angle of polarization (AoP) for each image frame pair using a field-programmable gate array (FPGA) wherein the FPGA is configured to:
determine the DoP by processing at least two image frame pairs of the plurality of image frame pairs; and
determine the AoP for the at least two image frame pairs based on the position of the polarizer received at the FPGA from the motor controller, and

wherein processing the at least two image frame pairs comprises adding a first frame of the first image frame pair to a first frame of the second image frame pair and subtracting a first frame of the first image frame pair from a second frame of the second image frame pair, the second image frame being consecutive with respect to the first image frame;
applying a spatial filter to both the DoP and AoP for each image frame pair to provide filtered images; and
searching the filtered images based on an amplitude of pixels relative to neighboring pixels to identify the pixels with a higher DoP relative to the neighboring pixels to identify a target.

10. The method of claim 9 , wherein determining the AoP for each image frame pair is based on the position of the polarizer.

11. The method of claim 9 , further comprising delaying the polarizer by 180-degrees of rotation with respect to an image acquisition rate of the imager of the first integrated circuit.

12. An object detection system comprising:
a digital read-out integrated circuit (DROIC) configured to measure scene data collected from a polarized image scene in which each image frame pair of the scene data from the polarized image scene is collected at two different and orthogonal polarizations;
a second integrated circuit configured to determine a degree of polarization (DoP) and an angle of polarization (AoP) for each image frame pair, to apply spatial filtering to the DoP and AoP for each image frame pair, and to generate pre-processed data as a result of the spatial filtering; and
a processor configured to match the pre-processed data to target criteria,
wherein the second integrated circuit comprises a field-programmable gate array (FPGA), wherein the second integrated circuit is configured to:
determine the DoP by processing at least two image frame pairs of the plurality of image frames, the processing including adding a first frame of the first image frame pair to a first frame of the second image frame pair and subtracting a first frame of the first image frame pair from a second frame of the second image frame pair; and
determine the AoP for the at least two frame pairs based on the position of a polarizer received at the second integrated circuit integrated circuit,
wherein processing the at least two image frame pairs comprises adding a first frame of the first image frame pair to a first frame of the second image frame pair and subtracting a first frame of the first image frame pair from a second frame of the second image frame pair, the second image frame being consecutive with respect to the first image frame.

13. The object detection system of claim 12 , further comprising:
a polarizer configured to polarize an incoming image scene, and to generate the polarized image scene;
a motor controller configured to control a spin rate of the polarizer; and
a lens configured to collect the scene data from the polarized image scene, the scene data including a plurality of image frames.

14. The object detection system of claim 12 , wherein the polarizer is delayed by 180-degrees by the motor controller of rotation to generate the AoP.

15. The object detection system of claim 1 , wherein the spatial filter is searching for targets that meet an expected dimension or targets where the AoP is unique with respect to immediate surroundings of the AoP.

Assignees

• Bae Sys Inf & Elect Sys Integ

Inventors

• Choiniere Michael J

Classifications

• G06V10/94

  Hardware or software architectures specially adapted for image or video understanding · CPC title

• G06V10/62

  relating to a temporal dimension, e.g. time-based feature extraction; Pattern tracking · CPC title

• G01J4/04

  Polarimeters using electric detection means (G01J4/02 takes precedence) · CPC title

• G06T2207/30236

  Traffic on road, railway or crossing · CPC title

• G06T2207/10016

  Video; Image sequence · CPC title