Greg R. Roelofs

San Jose, CA
(408) 866-5922
roelofs@pobox.com

Goal: To do challenging, innovative research or development in web search, imaging/graphics/visualization, compression, advanced user interfaces, or related areas, preferably in a Unix/Linux or cross-platform environment.
 
Education: University of Chicago University of Minnesota
    Ph.D., Physics (Radial Motions in Spiral Galaxies)           B.S., Physics  
    M.S., Physics             B.S., Astrophysics  
                  B.S., Mathematics  
 
Experience:   Yahoo! Sunnyvale, CA
Senior Member of Technical Staff ("Technical Yahoo!") on core runtime search-engine team, September 2004 to October 2007; Principal MTS, October 2007 to present. Rewrote core "results presentation" code to provide more intelligent and relevant summaries of web pages returned as users' search results; profiled and optimized code; managed search-engine releases and database performance-testing on rotating basis; helped monitor and troubleshoot "unusual behavior," such as specific types of hardware failure or unusual cluster latency; documented evolving design of summarization component and of overall search engine; led effort to expand, automate, and "robustify" runtime performance-testing infrastructure; etc.
 
Philips Semiconductors San Jose, CA
Software Architect and Research/Development Engineer, June 2001 to September 2004.
  • 2004: Helped create embedded-Linux SDK for triple-core (MIPS + two DSPs) processor, to support digital video and audio applications.
  • 2003-2004: Ported interprocessor-communication (IPC) module of internal SDE to triple-core, dual-OS processor; unified host RPC support across VxWorks, Windows, and Linux; added VxWorks protected-memory extensions.
  • 2001-2002: Part of new innovation and strategy group for home networking and consumer-electronics architectures, with special emphasis on Linux-based gateways and set-top boxes. Led development of first Linux distribution for dual-core (MIPS + VLIW DSP) processor and helped isolate and fix several toolchain, kernel, and hardware bugs.
 
Philips Research Sunnyvale, CA
Member of Technical Staff, August 1995 to April 1996; Senior MTS, April 1996 to May 2001. Researched and developed multiple projects, including Internet TV (WebTV-like prototype); GOLD, a hybrid image format designed for low-bandwidth channels (US 6,128,021); virtual communities, with emphasis on level-of-detail algorithms, scalability, and 3D navigation (US 6,270,414, US 6,765,572); the virtual CD jukebox (software design, audio codec optimization); the reliable home server, a series of Linux-based prototypes for home networking, remote monitoring, and remote control; and the context browser, a grab-bag of experimental techniques for managing large stores of text, images, audio and video clips, Web bookmarks, appointment and scheduling data, and ordinary computer files, with special emphasis on useful and natural navigation via a handheld device (US 7,047,500).
 
Open-source developer (Internet)
Shareware, open-source, and free/libre software developer, 1985 to present.
  • PNG Development Group, since 1995: Founding member of group to define, implement, and standardize (IETF, later ISO/IEC) a patent-free, lossless replacement for the GIF image format. Created (and still maintain) official Portable Network Graphics and Multiple-image Network Graphics home sites; wrote PNG: The Definitive Guide (O'Reilly, June 1999) and PNG chapter of the Lossless Compression Handbook (Academic Press, December 2002); wrote and/or contributed to numerous PNG-supporting programs (see Software below).
  • Info-ZIP, 1990-2004: Helped create and distribute portable, free compressor/archiver utilities. Contributed to Zip; led development of UnZip for eight years; maintained web site for more than ten.
 
Additionally, research experience at the University of Chicago and NASA Ames (simulation and visualization software, including a doubly iterative fitting program for galactic dynamics, a 2.5-dimensional gravitational hydrodynamics code, and particle dynamics codes), AT&T Bell Labs, Argonne National Laboratory, and Fermilab (summers); teaching experience (electronics, modern physics, electromagnetism, freshman physics); and excellent technical-writing skills (see Publications below).
 
Patents: Issued:
     
Dynamically Configurable Virtual Window Manager,
G. Roelofs; filed November 2001, issued May 2006 (US 7,047,500).
Apparatus and System for Abstract Visual Representation of Audio Signals
G. Roelofs; filed September 2001, issued August 2005 (US 6,937,211).
Virtual [Elephant] Modeling by Shadow-cast Voxel-clipping
G. Roelofs; filed April 2001, issued July 2004 (US 6,765,572).
Compensating for Network Latency in a Multi-player Game
G. Roelofs; filed March 2001, issued November 2002 (US 6,475,090).
Exoskeletal Platform for Controlling Multi-Directional Avatar Kinetics in a Virtual Environment
G. Roelofs; filed December 1997, issued August 2001 (US 6,270,414) and December 2002 (EP 0 974 087 B1).
Downloading Image Graphics with Accelerated Text Character and Line Art Creation
P. v. d. Meulen and G. Roelofs; filed October 1996, issued October 2000 (US 6,128,021).
  More than a dozen additional disclosures (user interfaces, micromachines, etc.) and filings (Force-Mediated [Font] Rasterization, Nonlinear Display Method for Data of Infinite Extent, Security System Simulates Patterns of Usage of Appliances, System and Method for Remote Control of Consumer Electronics over Data Network with Visual Feedback, Advanced Path Checker, Virtual Model Generation via Physical Components, GUI has Library Metaphor Based on Non-Euclidean Geometry, Handheld Retrieves UI from Server for Controlling Apparatus via Server).
 
Publications:
PNG Lossless Image Compression, in Lossless Compression Handbook, Academic Press (Elsevier Science), December 2002.
 
XV Viewer, Web Review, 10 December 1999.
 
PNG Gaining Acceptance, Web Review, 13 August 1999.
 
PNG: The Definitive Guide, O'Reilly and Associates, June 1999.
 
The Future of Linux, Linux Journal, October 1998.
 
PNG's Not GIF!, Web Review, 9 May 1997.
 
History of the Portable Network Graphics Format, Linux Journal, April 1997.
 
Take Command: unzip, Linux Journal, January 1997.
 
Radial Motions in Spiral Galaxies (dissertation), University of Chicago Press/UMI, December 1995.
 
Software: Primary author of pngquant (RGBA to RGBA-palette quantization and dithering); rpng/rpng2/wpng cross-platform demo programs (Unix, VMS, Win32); pngsplit (PNG chunk-extraction utility); UnZip; gpr (ASCII-to-PostScript converter); various Unix scripts and utilities; "which" clone for OS/2; original OS/2 port of Elvis (text editor); etc.
 
  Contributor to intel2gas (assembler-syntax converter), Firefox/Mozilla/Netscape 6+, Arena, X Mosaic, libpng, gif2png, tiff2png, pnmtopng/pngtopnm, pngcheck, XV, XPaint, giftool, Zip, lha, unrar, check/crc, file/magic, BSD mailx, BSD uuencode/uudecode (VMS port), hd (hex dumper), fm (hex editor), life (OS/2 screen saver), VMS zmodem, and others.
 
Technical: C/C++/STL, x86/x86-64 assembler, some Perl, FORTRAN, VRML; Unix/Linux and X development, 32-bit Windows, VxWorks, pSOS+, OS/2, DOS, VMS; PC, Sun, SGI, Cray, TriMedia, MIPS, and other hardware.

This page can be found at   http://gregroelofs.com/resume.html .
Last updated 30 August 2009.