Vinayak Hegde

Computer Graphics is one of the few fields in computer science which has immediate applications in the real world. The only other field in Computer science in which time from academic innovation to time-to-market is comparable is Computer Networking. Computer graphics derives from and drives a whole lot of related fields such as computer architecture, programming languages and physics. SIGGRAPH is “The Conference” if you are interested in anything related to computer graphics. The papers submitted are top-notch with more than a few techniques described in the papers making their way to movie theaters in the form of computer graphics.

Since I am an amateur photographer, I am generally interested in papers and techniques related to photography. Below are two of my favorite papers from the SIGGRAPH conferences of the this year and past year.

Enhancing Videos using Photographs

A recent paper which was presented at SIGGRAPH was really mind blowing. You can use high resolution photographs to improve the quality of an video with dramatic results. Also by adding effects to a series of frames or to the photographs you can do a variety of transformations on the video such as transfer better exposure from images to photograph or add high dynamic range or even add, touchup or remove objects. The video is worth a million words.

The paper (Using Photographs to Enhance Videos of a Static Scene) is available for download. This paper was presented in SIGGRAPH 2008 which concluded recently.

Seam Carving.

Seam carving uses the information in the picture to retain the important features of the photograph while resizing. So when you resize a photograph inconsistent with the proportional dimensions of the original photo – either the relative size of the important objects in the photo will diminish or they will expand giving an unreal or distorted feel to the whole photograph. Seam carving does away with this. The video below actually demonstrates the technique. Neat.

The paper (Seam Carving for Content-Aware Image Resizing) is available at the authors site for download. Something like this would be interesting to have in the GIMP. This paper was presented in SIGGRAPH 2007.

Interestingly the first edition of SIGGRAPH Asia is happening in Singapore from Dec 10-13, 2008.

Open Source developers contribute code for a variety of reasons:

1. To scratch an itch – fulfill a particular current need and release it to the world hoping that someone finds it useful.
2. To contribute back to the community they are part of or has helped them in the past.
3. Some contribute it because they enjoy writing code and feel altruistic because they help the world.
4. Some release code to help it get widespread adoption (marketing strategy by companies) so they can charge for premium support and build a community of committed contributers.

These varied motivations are visible in the multiple licenses in the Open Source community. The most popular licenses are GNU GPL, GNU LGPL, BSD, MIT and Apache Licenses. The relationship between these open source software (OSS) licenses is illustrated below :

Attribution: David Wheeler [http://www.dwheeler.com/essays/floss-license-slide.html]

Software was earlier delivered via floppies then CDROMS and now software downloads. Enter the internet and the web. They have completed changed the way people work and communicate. The web moved from static html pages to Web 2.0. Software is increasing moving away from the delivery to the “hosted” model. Computing resource acquisitions is moving from buying to renting. This has given rise to new paradigms of delivering software such as Software-as-a-Service or SaaS and Cloud Computing.

Open source software has been one of the key enablers of these new revolution alongwith open standards (HTML, HTTP, CSS, XML etc). Whether it is Linux or Apache or Firefox or Python. As mentioned above the GPL which is by far the most popular Open Source licence. When the GPL was written, the modes of software delivery were either through physical media or by downloading from a FTP server (GPL v2 was written in 1991 when the web was in it’s infancy). The GPL has a strong copyleft clause (called as tit-for-tat by Linus Torvalds) which was crucial to the success of Linux, GCC and MySQL – three of the building blocks of much of the SaaS and Cloud Computing infrastucture. It has given the programmers who contributed to it the confidence that their work would benefit the whole world and remain free for distribution, rather than being exploited by software companies that would not have to give anything back to the community. This ethos is central to the motivation of many of the programmers who contribute to open source software (OSS).

However the GPL has some “loopholes” which Application Service Providers (ASPs) exploit. Since the distribution clauses of GPL v2 (and now GPL v3) do not govern the software whose functionality is accessed over a network (mostly the Internet), ASPs and SaaS companies were able to make changes to OSS and not give them back to the community. The license that fixed this loophole was the Affero GPL v3. This has a clause that governs the usage of a software over the Internet.

13. Remote Network Interaction; Use with the GNU General Public License. Notwithstanding any other provision of this License, if you modify the Program, your modified version must prominently offer all users interacting with it remotely through a computer network (if your version supports such interaction) an opportunity to receive the Corresponding Source of your version by providing access to the Corresponding Source from a network server at no charge, through some standard or customary means of facilitating copying of software. This Corresponding Source shall include the Corresponding Source for any work covered by version 3 of the GNU General Public License that is incorporated pursuant to the following paragraph. Notwithstanding any other provision of this License, you have permission to link or combine any covered work with a work licensed under version 3 of the GNU General Public License into a single combined work, and to convey the resulting work. The terms of this License will continue to apply to the part which is the covered work, but the work with which it is combined will remain governed by version 3 of the GNU General Public License.

This clause is important to all Cloud Computing and SaaS vendors as any modifications they make to the software licensed under Affero GPL will have to be released to the users who use that software at nominal or no cost. This has made atleast a few vendors unhappy.

Continuing my Ladakh Photograph series with another photo. This photo was taken along the south-western bank of the Pangong Tso (pronounced with a silent T – Tso means Lake in Ladakhi). Part of the lake lies in China (Aksai Chin). You will need a inner-line permit (easily obtainable with the help of a local travel agent) to visit. If you are on a budget or are constrained by time you will have to choose between visiting one of the two major lakes in Ladakh – Pangong Tso and Tso moriri. Camping on the shores of Pangong Tso by night is an amazing experience because of the extremely clear skies.

To take this photo I put it my camera very close to the waters of the Pangong Tso to get a better wideangle shot. I have used this extremely well for shooting water-bodies. More technical details about the photo at my photoblog (click on Image Info).

The view from the top of Namgyal Palace which towers over the small town of Leh in Ladakh. Leh is very small but very welcoming place. The city market is just two streets wide with several old charming shops on either side with several antiques shops. The climb to the top of hill on which Namgyal Palace sits, is steep and tiring but the views are rewarding. One of the striking things you will soon notice about of the ladakhi landscapes are the contrasts in the landscapes around you. This photo shows that well.

I was going to Nubra valley when I took this photo. To go to Nubra valley, you have to cross the world’s highest motorable road – The Khardungla Pass. We went through the Khardungla pass during June 2006, when the snow was getting cleared. We were lucky that the pass was open as we could see the snow-ploughs of Border Roads Organisation continuously clearing the lower reaches of the pass on both the north and south sides of the pass. The best part of the photographs were the striations in the ridge and the snow melting in the side facing the sun which gives it zebra like stripes. We were initially planning to do a 3-day trip but cut it short by a day. How lucky we were as the pass was closed due to heavy snowfall from the 3rd day onwards for 3 more days.