July 2003

Our Chief Scientist, David Stork, has been doing some side research the past few years in art history. In particular he’s been assessing a theory that artist David Hockney presents in his book “Secret Knowledge”: that artists as early as 1430 have secretly used optical devices such as mirrors and lenses to help them create their almost photo-realistic paintings.

The theory is fascinating. Art historians know that some master’s used optical devices in the 1600’s, but Hockney and his collaborator Physicist Charles Falco claim that as early as 1430 the masters of the day used concave mirrors to project the image of a subject onto their canvas. The artist would then trace the inverted image. This alone, Hockney and his supporters claim, can account for the perfect perspective and “opticality” of paintings that suddenly appear at in this time period.

If the theory itself is fascinating, I find Stork’s refutation even more interesting. Stork’s argument is based on several points. First, he argues, there is no textual evidence that artists ever used such devices. Hockney and his supporters counter that the information was of course kept as a closely guarded trade secret, and that is why there was no description of it. It isn’t clear how these masters also kept the powerful patrons whose portraits they were painting from discussing their secret. Stork’s second argument is that, quite simply, the paintings aren’t all that perfect perspective after all. They look quite good, obviously, but if you actually do the geometry on the paintings Hockney presents as perfect you see that supposedly parallel lines don’t meet at a vanishing point as they would in a photograph. And third, Stork points out that the methods Hockney suggests would require huge mirrors to get the focal lengths seen in the suspected paintings: mirrors far far larger than the technology could create at the time.

My analysis is a little unfair to Hockney as I’ve only seen Stork’s presentation, but I must say I’m impressed with his argument. Hockney’s argument is quite media-pathic. It’s a mystery story that wraps history, secrecy, geniuses, modern science and great visuals all in one — no wonder it’s captured people’s attention! Unfortunately, I expect Stork’s right about one of the less fun aspects of the theory. It’s also probably dead wrong.

For those interested, a CBS documentary on Hockney’s theory will be rebroadcast this Sunday, August 3rd, on 60 Minutes.

References:

• Was It Done With Mirrors? (CBS 60 Minutes, 16 January 2003)
• Art & Optics (Conference Web Site, 1 December 2001)
• Further Reflections (Stork’s objections from the Art & Optics conference)
• Optical Projection in Renaissance Art: Did the Great Masters Cheat? (Interview with David Stork, Advanced Imaging, June 2003)
• FAQs about claims by David Hockney and Charles Falco on the purported use of optical devices by early Renaissance painters (David Stork’s page on the subject)

A couple weeks ago I attended the New Paradigms in Using Computers workshop at IBM Almaden. It’s always a small, friendly one-day gathering of Human-Computer Interaction researchers and practitioners, with invited talks from both academia and industry. This year’s focus was on the state of knowledge in our field: what we know about users, how we know it and how we learn it.

The CHI community has a good camaraderie, especially among the industry researchers. I suspect that’s because we’re all used to being the one designer, artist or sociologist surrounded by a company of computer scientists and engineers. Nothing brings together a professional community like commiseration, especially when it’s mixed with techniques for how to convince your management that what you do really is valuable to the company.

One of the interesting questions of the workshop was how to share knowledge within the interface-design community. Certainly we all benefit by sharing knowledge, standards and techniques, but for the industry researchers much of that information is a potential competitive advantage and therefore kept confidential. Especially here in Silicon Valley, that kind of institutional knowledge gets out into the community as a whole through employment churn, as researchers change labs throughout their careers.

Here are my notes from several of the talks. Standard disclaimers in place: these are just my notes of the event and subjected to my own filters and memory lapses. If you want the real story, get it from the respective horses’ mouths.

Electronic voting is getting slammed this week. First, Dan Gillmor’s Sunday Column took election officials to task for not insisting on providing physical paper trails that can be followed should the results of an election be in doubt. Then on Wednesday several computer security experts at Johns Hopkins University and Rice University published a scathing analysis of the design of the Diebold AccuVote-TS, one of the more commonly used electronic voting systems, based on source code that the company accidentally leaked to the Internet back in January. Exploits include the ability to make home-grown smart-cards to allow multiple voting, the ability to tamper with ballot texts, denial of service attacks, the potential to connect an individual voter to how he voted, and potentially the ability to modify votes after they have been cast. The New York Times and Gillmor’s own blog have since picked up the report. Diebold has since responded to the analysis, but at least so far they haven’t addressed the most damning criticisms.

There are several lessons to be learned from all this:

Frank Moss, US deputy assistant secretary for Passport Services, announced at the recent Smart Card Alliance meeting that production of new smart-card enabled passports will begin by October 26, 2004. Current plans call for a contactless smart chip based on the ISO 14443 standard, which was originally designed for the payments industry. The 14443 standard supports a data exchange rate of about 106 kilobytes per second, much higher than that of the widely-deployed Speedpass system.

Nearly six years to the day after the process was started, it looks like the IEEE is honing in on a single standard for a fast (around 100 Mbit/s), short-range (< 10m), low-power, low-cost wireless communication. The standard, which will be IEEE 802.15.3a, comes out of the IEEE Wireless Personal Area Network (WPAN) working group. Unlike cellular or Wi-Fi networks, the point of a personal area network is to communicate with other devices that are there in the room with you. For example, a high-speed WPAN would allow your PDA to stream video directly to a large-screen TV. Alternatively, your core CPU could wirelessly communicate with medical sensors, control buttons, displays and ear-pieces, all distributed around the body. The standard fills much the same niche as Bluetooth (the first standard adopted by the working group, also known as 802.15.1), but the new technology is significantly faster than Bluetooth (up to 100 times faster, according to champions of the technology).

Trade news columnists who know more than I do about this are picking Texas Instruments’ proposal for OFDM UWB (that’s Orthogonal Frequency Division Multiplexing Ultra Wide Band, thank you for asking) as the likely technology to be picked. Assuming it does, TI’s UWB business development manager says we can expect to see the first UWB products hitting the marketplace in 2005.

Update: The standard did not receive enough votes to pass, and will be voted on again in mid-September.

References:

• IEEE 802.15 Website
• Wireless raises the final standard (ZDNet, 22nd July 2003)
• Basis of UWB Spec Could Be Decided This Week (Electronic News, 21st July 2003)
• Military’s ‘sneaky wave’ out of hiding (C|net, 11 March 2003)
• Texas Instruments’ UWB page