Tracking Migratory BirdsAround Large Structures

by Arik Brooks and Nicholas Patrick

Senior Design Project 2003-2004Bradley University

Department of Electrical and Computer Engineering

Outline

1. Background2. Project summary3. Previous Work4. Detailed description

1. System block diagram2. Subsystems3. Modes of operation4. Design equations

Outline

• Preliminary design work• Datasheet• Schedule• Standards/Patents• References• Equipment List

Background

• Every year, many birds are killed when their migration path takes them near tall structures.

• This usually occurs on overcast nights, and one widely accepted theory on why these bird kills happen is that the birds do not want to leave the lighted area near a structure and end up running into it.

Project Summary

• The purpose of this project is to implement a system to track the trajectories of birds flying within the field of view of a set of cameras mounted on a rotatable boom in realtime.

• The positions of the birds are determined using stereoscopic vision by placing the two cameras a known distance apart in parallel with each other.

Project Summary

• The system output is a display depicting a three dimensional representation of the trajectories, and data relating to the trajectories.

• Inputs to the system include the position of the boom, images detected by the cameras, calibration information, and confidence level threshold.

Previous Work

• Seniors Brian Crombie and Matt Zivney worked on a senior project in Spring 2003 with the goal of tracking birds around tall structures via stereoscopic imaging.

• They achieved basic object tracking in a laboratory environment with major limitations.

• The groundwork laid out in their project (algorithms, design equations, software organization, etc.) will be used as a starting point for our system.

Detailed Description

System Block Diagram

System

Hardware Block Diagram

Subsystems

• Cameras

• Boom

• Frame Grabber

• PC

• Display and Interface

Camera Subsystem

• The camera subsystem includes two cameras mounted in parallel a known distance apart allowing objects to be located in space.

• Inputs– Photons -- Images from the environment within the

field of view of the cameras– Synchronization signal -- Signal from an external

source (frame grabber) to coordinate the capturing of images

• Outputs– Data -- Image data transmitted to the frame grabber

• Operation in Modes– The cameras capture images continuously

Boom Subsystem

• The boom subsystem holds the cameras in parallel and rotates via a stepper motor.

• The position of the boom is determined from the output of an encoder.

• Inputs– Stepper Motor Control Signal -- Rotates the boom in

two directions• Outputs

– Encoder Output -- Signal to the PC to determine the current angle of the boom

• Operation in Modes– The boom operates (changes position) only in Setup

mode

Frame Grabber Subsystem

• The frame grabber simultaneously captures images from both cameras and supplies the data to the PC.

• Inputs– Data -- Image data from the cameras– Setup -- Information from the PC

• Outputs– Image Data to PC– Synchronization Signal -- Signal to the cameras to

coordinate the capture of images• Operation in Modes

– The frame grabber operates continuously along with the cameras

PC Subsystem

• Inputs– Image Data -- Arrays of intensity information

from the frame grabber representing the collected images

– Encoder -- Angle information from the boom encoder

– Desired Boom Position -- Input from the user for desired boom position

– Real-time/Delay -- Input from user determining whether or not to calculate and display the trajectory information in real-time

– Calibration Input -- Calibration data for the cameras being used

– Confidence Level -- User defined level of non-linearity in trajectories allowable for consideration

PC Subsystem

• Outputs– Display -- Trajectories displayed in a three

dimensional representation and graphical user interface

– Statistics -- Pertinent information about the objects locations and trajectories (e.g. Number of birds within x distance of the cameras, maximum velocity, etc.)

– Raw Data -- Data file containing all position data for later analysis

• Operation in Modes– The PC is continuously operating in every

mode

Display and Interface Subsystem

• The trajectories will be displayed on a standard computer monitor.

• The user will interface with the system using a standard computer keyboard and mouse.

• Inputs– Display Information– User Inputs

• Outputs– Image Display– User Data

• Operation in Modes– The Display and Interface will be used in Setup and

Display modes

Modes of Operation

• Setup• Monitoring• Data Acquisition• Display and Computation

Setup Mode

Monitoring Mode

Data Acquisition Mode

Display and Computation Mode

Design Equations

Preliminary Design Work

• Based on preliminary work performed in the laboratory, it was determined that a better method of transient object correlation needs to be implemented to achieve the tracking of a large number of objects at one time.

• When objects cross paths or get close to each other, the current transient correlation algorithm fails to differentiate between those objects accurately and errors occur.

Preliminary Design Work

Preliminary Design Work

• The basic flow of the software to be designed including better organization and correlation method was determined.

• Preprocessing– Read in image, record initial time stamp and

time between frame grabs– Discard areas that are not within field of view of

both cameras– Perform a background subtraction to extract

moving objects– Threshold and convert each image to B/W– Apply filters– Find areas/centroids of all objects

Preliminary Design Work

• Correlation/Trajectory– Input areas/centroids found in preprocessing– Save data for later use– Find every “possible” 3d position for the objects

in the present frame • to be “possible”, must be within 30 pixels of each

other between cameras in horizontal position

– continued...

Preliminary Design Work

• Correlation/Trajectory (continued)– Search for closest position to predicted

position, within the user defined threshold, for each object based on its previous two locations

– Search for objects that were first detected in the previous frame based on closest position and area within a threshold (Different from the user defined threshold)

– Correlate any remaining objects between two cameras based on closest horizontal distance and area

– Calculate new predicted positions for any object with two or more data points in time

– Display

Datasheet

• Average Migratory Bird Size (AMBS): TBD• Max # of Objects Tracked Simultaneously: TBD• Max Distance from Cameras: TBD• Min Distance from Cameras: TBD• Max Location Error: TBD• Light Level Sensitivity:

– Lab Cameras: 0.22 Lux– Low Light Cameras: 0.0002 Lux

• Max Framerate: TBD• System Latency: TBD• Max Trackable Bird Speed: TBD• Total Volume of Space Observed: TBD• Boom Rotation Step Resolution: TBD

Test Plan

• There will be four primary test procedures that will be performed to verify the system specifications:

• Location Accuracy– track an AMBS object in known trajectories

(including trajectories proceeding primarily towards and away from the cameras) and compare the measured and actual locations

• Max/Min Distance from Cameras– track an AMBS object in known trajectories and

check accuracy/ability to track• Max # Objects

– TBD• Contrast Resolution

– track objects of various known intensities in front of a variety of backgrounds

Schedule

Week beginning Task Assigned to

1/22 Research/Develop algorithms to improve tracking and correlation

Determine final output to the user and layout of the user interface

Both

1/29 Implement final preprocessing code in C++Implement improved algorithms in MATLAB for

testing

NickArik

2/5 Continued Both

2/12 Continued Both

2/19 Integrate new cameras to systemPort MATLAB to C++

NickArik

2/26 Develop Graphical User Interface for system and continue other software development

Both

Schedule

3/4 Continued Both

3/11 Test system in near real environment Both

3/18 Attend wet T-shirt contest in Cancun Both

3/25 Develop and implement final boom system and stepper motor

Both

4/1 Continued and create test plan and final specifications

Both

4/8 Test system Both

4/15 Continued and make any necessary changesPrepare for Expo presentation

Both

4/22 Prepare final report and presentation Both

5/6 Give presentation Both

Standards

• There are no overarching standards that apply to bird tracking, but several standards are used to interface cameras to the PC.

• NTSC– The cameras selected produce NTSC compatible

signals, which is the standard in North America – The Frame Grabber converts NTSC inputs to digital

images• DirectX

– DirectX is a defacto standard for Microsoft Windows which includes a programming interface to video capture devices such as frame grabbers

– DirectX was chosen over proprietary APIs to maintain a maximum amount of hardware independence

Patents

• Patent #6,366,691– Stereoscopic image processing apparatus and

method

• Patent #6,028,954– Method and apparatus for three-dimensional

position measurement

• Patent #6,035,067– Apparatus for tracking objects in video

sequences and methods therefor

• Patent #5,812,269 – Triangulation-based 3-D imaging and

processing method and system

Referenceshttp://www.intel.com/research/mrl/research/openCV/

Pinhole camera model, image processing reference.http://www.digibird.com/primerdir/eqn.gif

Equations relating focal length to zoomhttp://www.ipsimaging.com/support/camerasensitivity.htm

Light levels for various time of day and weather conditions.http://sportscience.org/adi2001/adi/services/support/faq/software_genlock.asp

Estimating position when synchronized cameras are not available.http://www.fmsystems-inc.com/vtmtips_article.htm

Using line lock cameras.http://www.imaginghardware.com/Tutorials/Docs/t00002A.asp

Equation relating focal length to target object size, distance, and CCD width.http://www.machinevisiononline.org/public/articles/cohu.PDF

Measurements for various CCD sizes.http://cegt201.bradley.edu/projects/proj2003/birdtrak/pdf/proj_prop.pdf

Project proposal from previous group

Chen, Tieh-Yuh; Bovik, Alan Conrad; Cormack, Lawrence K. “Stereoscopic Ranging by Matching Image Modulations,” IEEE Transactions on Image Processing. Vol 8, # 6, June 1999, pg 785-797.

Equipment List

• Cameras and Lenses– Lab

• Sanyo VCB-3444

• Rainbow L8DC4P Auto Iris Lens

– Low Light• Hitachi KP-200E

– $920 at www.opsci.com

• DV10x7.5A-SA2 Auto Iris Lens– $273 at www.opsci.com

Equipment List

• Video Capture Card– Data Translation DT3132 Dual

Frame Grabber• Supports simultaneous acquisition

of images from two sources.

• Programmable through DirectX

Equipment List• PC

– Windows 2000 or higher OS– DirectX 8.1 or higher installed– One PCI slot for frame grabber– Enough processor power for real-

time operation– Development software

• DirectX 8.1 SDK• Microsoft Visual Studio 6.0• MATLAB 6.5 with image

processing toolbox

Tracking Migratory BirdsAround Large Structures

Questions?