3D_Object_Recognition_Slides_Lee

Report
3D Object Recognition Using
Computer Vision
VanGogh Imaging, Inc.
Kenneth Lee
CEO/Founder
[email protected]
Corporate Overview
Founded in 2007, located in McLean VA
Mission: “Provide easy to use, real-time 3D computer vision
(CV) technology for embedded and mobile applications”
– 2D to 3D for better visualization, higher reliability, and accuracy
– Solve problems that require spatial measurements (e.g. parts inspection)
Target customer: Application and System Developers
– Enhance existing product or develop new products
Product: ‘Starry Night’ 3D-CV Middleware (Unity Plugin)
– Operating Systems: Android and Linux
– 3D Sensor: Occipital Structure and Intel RealSense
– Processors: ARM and Xilinx Zynq
Our focus
– Object recognition
– Feature detection
– Analysis (e.g., measurements)
Potential Applications
3D Printing
Parts Inspection
Robotics
Security
Entertainment
Automotive Safety
Medical Imaging
Challenges for Implementing
Real-Time 3D Computer Vision
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Busy uncontrolled real-world environment
Limited processing power and memory
Noisy and uncalibrated low-cost scanners
Difficult to use libraries
Hard to find proficient computer vision engineers
Lack of standards
Large development investment
Starry Night Unity Plugin
(patent pending)
Starry Night Video:
https://www.youtube.com/watch?v=IZX-9PH7Erw&feature=youtu.be
The ‘Starry Night’ Template-Based
3D Model Reconstruction
Reliable - The output is always a fully-formed 3D model with known
feature points despite noisy or partial scans
Easy to use – Fully automated process
Powerful – Known data structure for easy analysis and measurement
Fast – Real-time modeling
Input Scan (Partial) + Reference Model = Full 3D Model
3D Object Recognition
Algorithm
for mobile and embedded Devices
Challenges - Scene
Busy scene, object orientation, and occlusion
Challenges - Platform
Mobile and Embedded Devices
– ARM – A9 or A15, <2G RAM
– Existing libraries were built for laptop/desktop platform
– GPU processing is not always available
Previous Approaches
(2D) Texture-Based Methods
– Color-based → depends heavily on lighting or color of the object
– Machine learning → robust, but requires training for each object
– Neither method provides transform (i.e., orientation)
(3D) Methods
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Hough transform and geometric hashing → slow
Geometric hashing → even slower
Tensor matching → not good for noisy and sparse scene
Correspondence-based methods using rigid geometric descriptors
– The models must have distinctive feature points which is not true
for most models (i.e., cylinder)
Tried
General Concept for CV-Based
Object Recognition
Reference
Object
Descriptor
Distance & Normal
Match Criteria
Compare
Scene
Distance & Normal of
Random Sample Points
Fine-Tune
Orientation
Location
Transpose
Block Diagram
Model Descriptor (Pre-Processed)
Sample all point
pairs in the model
that are separated by
the same distance D
Use the surface
normal of the pair to
group them into the
hash tablet
Note: In the bear example, D = 5 cm which resulted
in 1000 pairs
Note: The keys are angles derived from the normal of
the points.
alpha(α) = first normal to second point
beta(β) = second normal to first point
omega(Ω) = angle of the plane between two points
key
(α1,β1,Ω1)
P1, P2
P3, P4
(α2,β2,Ω2)
P5, P6
P7, P8
(α3,β3,Ω3)
P13, P14
P9, P10
P11, P12
Object Recognition Workflow
Grab Scene
Sample point pair w/
distance D using
RANSAC
Generate key using
same hash function
Use key to retrieve
similarly oriented
points in the model &
rough transform
Match criteria to find
the best match
Note: The example scene has around 16K points
Note: We iterated this sampling process 100 times
Note: Entire process can be easily parallelized
Very Important: Multiple models can be
found using a single hash table, for
example, sampled point pair in the scene
Use ICP to refine
transform
Implementation
Result
Object Recognition Video:
https://www.youtube.com/watch?v=h7whfei0fTw&feature=youtu.be
Object Recognition Examples
* CONFIDENTIAL *
18
Adaptive 3D Object
Recognition Algorithm
Resize and Reshape
Object Recognition
for Different Sizes & Shape
Objects in the real world are not always identical
Similarity Factor, S%, can be used to denote % of
shape difference
– This allows recognition of object that’s similar but does not have the
exact shape as the reference model
Size Factor, Z%, can be used to note the % size
the object can recognize
– This allows recognition of object that’s of different sizes from the
reference model
General Approach
Dynamically resizes the reference model
Dynamically reshapes the reference model
– Uses our ‘Shape-based Registration’ technique
Hence, the reference model is ‘deformed’ to match
the object in the scene
Results in very robust object recognition
The end reference model best represents the
object in the scene both in size and shape
Block Diagram – Adaptive Object
Recognition with feedback
Reference model is iteratively modified with every
new frame until it converges into the same object
in the scene
Note: Currently in the process of being implemented
and will be available in Version 1.2 later this year
Object Recognition
Performance Numbers
Reliability (w/ bear model)
Reliability
– % false positives – depends on the scene
– Clean scene: <1%
– Noisy scene: 5% (1 out of 20 frames)
– % negative results (cannot find the object)
– Clean scene: <1%
– Noisy scene: 10% (also takes longer)
Effect of orientation on success ratio
– Model facing front: >99%
– Model facing backwards: >99%
– Model facing sideways (narrower): 85%
Performance - Mobile
Performance on Cortex A-15 2GHz ARM (on
Android mobile)
– Amount of time it takes to find one object
– Single thread: 2 seconds
– Multi-thread & NEON: 0.3 second
– Amount of time it takes to find two objects
– Single thread: 2.5 seconds
– Multi-thread & NEON: 0.5 second
Note: Effective use of NEON led to significant performance gains of
X2.5 for certain functions
Hardware Acceleration Using FPGA
• Xilinx Zynq SoC provides
20 to 1,000 parallel voxel
processors depending on
the size of the FPGA
Zynq
FPGA
voxel
voxel
ARM
voxel
scan
voxel
voxel
Processor 1
Processor 1
Processor 1
Processor 1
Processor 20+
Hardware Acceleration:
FPGA (Xilinx Zynq)
Select Functions to Be Implemented in Zynq
– FPGA: Matrix operations
– Dual-core ARM: Data management + Floating point
– Entire implementation done in C++ (Xilinx Vivado-HLS)
Performance:
Embedded Using FPGA
Note: Currently, only 30% of the computationally
intensive functions are implemented on the FPGA
with the rest still running on ARM A9. Speed will be
much improved once the remaining high-intensity
functions are transferred to the FPGA.
Performance on Xilinx Zynq (Cortex A-9 800 MHZ
+ FPGA)
– Amount of time it takes to find one object
– Zynq 7020: 0.7 second
– Zynq 7045 (est.): 0.1 second
– No test results for two objects, but should scale the same way as for
the ARM
Future
The chosen algorithm works well in most real-world
conditions
The chosen algorithm is tolerant to size and shape
differences respect to the reference model
The chosen algorithm can find multiple objects at the
same time with minimal additional processing power
Additional improvements in performance are needed
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Algorithm
Application-specific parameters (e.g., size of the model descriptor)
ARM - NEON
Optimize the use of FPGA core
Summary
Key implementation issues
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Model descriptor
Data structure
Sampling technique
Platform
IMPORTANT
– Both ARM & FPGA provide the scalability
Therefore
– Real-time 3D object recognition was very difficult but
successfully implemented on both mobile and embedded
platforms!
LIVE DEMO AT THE Xilinx BOOTH!
Resources
www.vangoghimaging.com
Android 3D printing: http://www.youtube.com/watch?v=7yCAVCGvvso
“Challenges and Techniques in Using CPUs and GPUs for Embedded
Vision” by Ken Lee, VanGogh Imaging—http://www.embeddedvision.com/platinum-members/vangogh-imaging/embedded-visiontraining/videos/pages/september-2012-embedded-vision-summit
“Using FPGAs to Accelerate Embedded Vision Applications”, Kamalina
Srikant, National Instruments— http://www.embeddedvision.com/platinum-members/national-instruments/embedded-visiontraining/videos/pages/september-2012-embedded-vision-summit
“Demonstration of Optical Flow algorithm on an FPGA”—
http://www.embedded-vision.com/platinum-members/bdti/embeddedvision-training/videos/pages/demonstration-optical-flow-algorithm-fpg
* Reference: “An Efficient RANSAC for 3D Object Recognition in Noisy
and Occluded Scenes” by Chavdar Papazov and Darius Burschka.
Technische Universitat Munchen (TUM), Germany.

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