Alexander Patterson IV
Ph.D. Candidate

GRASP Laboratory
Department of Computer and Information Science
University of Pennsylvania
Advisor:
Kostas Daniilidis
xandey (at) gmail.com

Google Scholar Profile
Publications
Projects
Software
CV (PDF)

I have accepted a position at Sightlogix beginning November 2013.

Current Interests:

My main research topic is laser scan data. Range images contains a different sort of data from traditional images, and presents specific challenges that are not always present in other imaging modalities. I am interested in the fields of object recognition, learning, registration between image and range data, and data fusion between range images and other modalities. I have been contributing to this field since 2006.

Publications:

Automatic Alignment of a Camera with a Line Scan LiDAR System
Oleg Naroditsky, Alexander Patterson IV, Kostas Daniilidis
IEEE International Conference on Robotics and Automation, May 2011.
Download: [PDF] [CODE]

Object Detection from Large-Scale 3D Datasets using Bottom-up and Top-down Descriptors
Alexander Patterson IV, Philippos Mordohai, Kostas Daniilidis
European Converence on Computer Vision, October 2008.
Download: [PDF]

Fully Automatic Registration of 3D Point Clouds
Ameesh Makadia, Alexander Patterson IV, Kostas Daniilidis
IEEE Conference on Computer Vision and Pattern Recognition, New York, June 2006.
Oral Presentation (CVPR06 accepted 6% of submitted papers for oral presentations)
Download: [PDF] [CODE]

Digitizing Archaeological Excavations from Multiple Views
Xenophon Zabulis, Alexander Patterson IV, Kostas Daniilidis
International Conference in 3D Digital Imaging and Modeling, June 2005.
Download: [PDF]

Written Preliminary Exam II: 3D Pose Estimatino in Point Clouds
Alexander Patterson IV
Download: [PDF]

Projects:

Highway Mapping: Designed and implemented a calibration solution for acquiring city scale georeferenced stereo image data. Sensors fused were Hokuyo line scan LiDAR, PointGrey Flea2 cameras, and OxTS IMU-GPS. Helped develop hardware capture system for real time scanning system which was used to scan the Cypriot highway system at an ultimate accuracy of 10cm. This work leveraged the LiDAR-Camera calibration result. The companies involved were Kapou and Geomatic Technologies.

Complex Mapping: Designed and Implemented pan/tilt scan-head software for real time 3D mapping and data fusion of stereo cameras and laser scan data. Collaborated closely with Sarnoff Corporation. Replicated the Sarnoff designed robot using a spare segway and parts from our lab. Included custom integration and capture software/hardware for our Hokuyo and 4 cameras.

ARM-S: Autonomous Robotic Manipulation Software Track DARPA project. Built object recognition modules for recognizing objects and their poses in a constrained environment. Also built a system to replace the supplied robot calibration routines including hand-eye, camera, and camera-range image calibrations. Collaborated with IRobot.

URGENT: Urban Reasoning and Geospatial Exploitation Technology DARPA laser scanner mapping project with the eventual goal of building a system capable of city scale processing with semantic object classification. We implemented segmentation and object recognition components.

Range Image Registration: Developed and released code which automatically calibrates the transformation between range image scans using a novel global feature, the Constellation Extended Gaussian Image.

Archaeoviz: 3D image mapping for archaeology. Developed calibration and reconstruction algorithms suitable for use in archaeological environments using surveyed markers both for calibration and to constraing the stereo search range. Included fieldwork in Bolivia.

TeleImmersion: Developed a stereoscopic OpenGL viewer for use with the Teleimmersion system including a virtual object interaction demonstration for teleconferencing application. Also developed a camera simulator for planning out camera placement in software. This project lives on at UC Berkeley.

JptView: The Java OpenGL Point Cloud Viewer (JptView) is intended to visualize pointclouds both inside and outside Matlab, and as an interface to perform manual segmentations. The source is released under the GPL.

Calib2GL: Calibrated OpenGL camera simulator that I wrote for the Teleimmersion Project.

Debunked (aired June 17, 2004): Featured explaining the details of measuring how spherical ancient stone balls are for the Discovery Channel.

Software:

Camera-3D Scanner Calibration: The matlab [code], available under the BSD license, computes the transformation between a camera and laser scanner given 2D image (line) to 3D (point) correspondences and the camera calibration matrix.

3D Range Image Registration: The matlab [code], available under the BSD license, computes the transformation between two 3D laser scan images given the point locations and estimated surface normals.

JptView: The Java OpenGL Point Cloud Viewer (JptView) is a tool which visualizes pointclouds both inside and outside Matlab, and as an interface to perform manual segmentations. The [code] is available.

Calib2GL: Calibrated OpenGL camera simulator that I wrote for the Teleimmersion project. The [code] is available.

Updated 8/2013