Archive for June 2007
Non-photorealistic rendering emerged out of the need for researchers to render a scene in styles other than photorealistic. Researchers have published their excellent work on topics as diverse as painterly rendering, charcoal rendering, pen-and-ink rendering, blueprint rendering and sketch drawing.
Painterly rendering as mentioned above is a type of non-photorealistic rendering. It deals with generating an image that mimics a painter’s attempt at generating a painting of a particular scene. This topic has received immense attention due to its “coolness factor” as well as complexity. The top image depicts a photograph which is used as input to the algorithm that generates the painterly rendering shown below the photograph. Image credits: Aaron Hertzmann, ‘Painterly Rendering with Curved Brush Strokes of Multiple Sizes’, Siggraph ’98.
Here is a small (definitely incomplete) list of papers that attempt to generate painterly rendered outputs based on various inputs (scenes, photographs and virtual environments).
- Painterly Rendering with Curved Brush Strokes of Multiple Sizes
A. Hertzmann. SIGGRAPH 98 Conference Proceedings. pp. 453-460. Orlando, Florida. July, 1998.
- Peter Litwinowicz, Processing images and video for an impressionist effect, Proceedings of the 24th annual conference on Computer graphics and interactive techniques, p.407-414, August 1997
- Steve Strassmann, Hairy brushes, ACM SIGGRAPH Computer Graphics, v.20 n.4, p.225-232, Aug. 1986
- Barbara J. Meier, Painterly rendering for animation, Proceedings of the 23rd annual conference on Computer graphics and interactive techniques, p.477-484, August 1996
- Cassidy J. Curtis , Sean E. Anderson , Joshua E. Seims , Kurt W. Fleischer , David H. Salesin, Computer-generated watercolor, Proceedings of the 24th annual conference on Computer graphics and interactive techniques, p.421-430, August 1997
- Maria Shugrina , Margrit Betke , John Collomosse, Empathic painting: interactive stylization through observed emotional state, Proceedings of the 4th international symposium on Non-photorealistic animation and rendering, June 05-07, 2006, Annecy, France
- Paul Haeberli, Paint by numbers: abstract image representations, Proceedings of the 17th annual conference on Computer graphics and interactive techniques, p.207-214, September 1990, Dallas, TX, USA
- James Hays , Irfan Essa, Image and video based painterly animation, Proceedings of the 3rd international symposium on Non-photorealistic animation and rendering, June 07-09, 2004, Annecy, France
- Aaron Hertzmann, Fast paint texture, Proceedings of the 2nd international symposium on Non-photorealistic animation and rendering, June 03-05, 2002, Annecy, France
- Doug DeCarlo , Anthony Santella, Stylization and abstraction of photographs, Proceedings of the 29th annual conference on Computer graphics and interactive techniques, July 23-26, 2002, San Antonio, Texas
This list can go on forever, but you get the idea.
After that introduction of painterly rendering, I can now discuss the application of the rich medium of paintings in the field of visualization. In the field of visualization, attributes such as brush size, color, orientation, texture and so on can be used for visualizing all the multiple attributes that comprise a dataset.
Painterly visualization is an interesting approach to visualizing scientific data. Researchers not only end up producing aesthetically pleasing images but also generate visualizations that domain experts can better use to visualize and understand their data.
Prof. Chris Healey from NCSU has been one of the primary researchers using the painterly rendering paradigm to visualize weather and other multi-attribute datasets. Some other work has emerged from the labs of Prof. David Laidlaw at Brown, Prof. Victoria Interrante at UMN.
Here are some of their papers and some other related papers. The beautiful painterly visualizations generated not only make it enjoyable but the techniques and the applications sure make for extremely interesting reading.
- Tateosian, L. G., Healey, C. G., and Enns, J. T. “Engaging Viewers Through Nonphotorealistic Visualizations.” To appear in Fifth International Symposium on Non-Photorealistic Animation and Rendering (San Diego, California, 2007).
- Healey, C. G and Enns, J. T. “Perception and Painting: A Search for Effective, Engaging Visualizations.” IEEE Computer Graphics & Applications (Visualization Viewpoints) 22, 2, (2002), 10-15.
- P. Coleman Saunders, Victoria Interrante and Sean C. Garrick (2005) “Pointillist and Glyph-Based Visualization of Nanoparticles in Formation“,, Joint Eurographics/IEEE-VGTC Symposium on Visualization”, pp. 169-176.
- Healey, C. G., Enns, J. T., Tateosian, L. G., and Remple, M. “Perceptually-Based Brush Strokes for Nonphotorealistic Visualization.” ACM Transactions on Graphics 23, 1, (2004), 64-96.
- Michael Kirby, Daniel Keefe, and David H. Laidlaw. Painting and Visualization. In Visualization Handbook. Academic Press, June 2004.
- Kirby, R. M., Marmanis, H., and Laidlaw, D. H. Visualizing Multivalued Data from 2D Incompressible Flows Using Concepts from Painting. In Proceedings of the 10th IEEE Visualization 1999 Conference (VIS ’99) (October 25 – 28, 1999).
This too is by no means a complete list and any input regarding additions will be appreciated.
Visualization researchers enjoy coming up with innovative techniques to visualize their data. The field almost borders on art where design choices, color choices and many other decisions can make the generated visualization very appealing.
But, the least favorite part of the work that visualization researchers have to do (or are strongly encouraged to do) is a formal evaluation of their visualization techniques. It requires one to be fair and ensure that one’s techniques are being accurately evaluated without any bias.
As one would imagine, the practitioners have observed this reluctance on the part of their peers to conduct user studies and to do it well. A particularly well written paper by Ellis and Dix discusses why conducting a user study is hard and how many user studies are conducted haphazardly, in a biased manner to ensure success for their techniques. My favorite paragraph from this paper is
”If your aim is to prove that your system is best, go get a job as an advertising executive. If your aim is simply to make your system as good as possible, then sell your product but don’t write about its development. If your aim is to make your product as good as possible in order to effectively deploy it and so learn, this is essential, but not a thing to report in detail. However, if your aim is to understand whether, when and under what circumstance a technique or design principle works or is useful – yes now you are doing research.”
They have also cited some excellent work by researchers in the field of HCI.
- Henry Lieberman from MIT Media labs - Rant: The Tyranny of Evaluation and
- Shuman Zhai’s reply Evaluation is the worst form of HCI research except all those other forms that have been tried
These definitely make for very interesting reading.
There are other researchers who want to share their experience on the topic of conducting a user study and help new researchers who are about to embark on their first user study. Some excellent papers have been written covering topics such as why should one bother conducting a user study in the first place or why should one take the trouble of finding experts and getting one’s techniques evaluated from them and so on. I would highly recommend reading some of these papers first:
- Robert Kosara, Christopher G. Healey, Victoria Interrante, David H. Laidlaw, Colin Ware, Thoughts on User Studies: Why, How, and When, IEEE Computer Graphics & Applications (CG&A), Visualization Viewpoints, vol. 23, no. 4, pp. 20-25, July/August 2003. http://www.kosara.net/papers/Kosara_CGA_2003.pdf
- G. Ellis and A. Dix(2006). An explorative analysis of user evaluation studies in information visualization. In Proceedings of the 2006 Conference on Beyond Time and Errors: Novel Evaluation Methods For information Visualization (Venice, Italy, May 23 – 23, 2006). BELIV ’06. ACM Press, New York, NY, 1-7.
- Plaisant, C. The Challenge of Information Visualization Evaluation. Advanced Visual interfaces, Italy, 2004, ACM Press. http://hcil.cs.umd.edu/trs/2004-19/2004-19.pdf
- Tory, M., Möller, T. Evaluating Visualizations: Do Expert Reviews Work? IEEE Computer Graphics and Applications, 25(5), 2005, 8-11.
Here are some researchers and research groups who have taken the effort to conduct a user study correctly and evaluate their results.
- Chris North and Ben Shneiderman(2000), Snap-Together Visualization: Can Users Construct and Operate Coordinated Views?,International Journal of Human-Computer Studies, Academic Press, vol. 53, no. 5, pp. 715-739. http://people.cs.vt.edu/~north/papers/snap-IJHCS.pdf
- David H. Laidlaw, Michael Kirby, Cullen Jackson, J. Scott Davidson, Timothy Miller, Marco DaSilva, William Warren, and Michael Tarr (2005). Comparing 2D vector field visualization methods: A user study. Transactions on Visualization and Computer Graphics, 11(1):59-70, January-February 2005. http://www.cs.brown.edu/research/vis/docs/pdf/Laidlaw-2005-CVF.pdf
- An Evaluation of Pan &Zoom and Rubber Sheet Navigation with and without an Overview. D. Nekrasovski, A. Bodnar, J. McGrenere, F. Guimbretiére, T. Munzner. http://www.cs.ubc.ca/nest/imager/tr/2006/Nekrasovski2006CHI/
- Kobsa, A. (2004): User Experiments with Tree Visualization Systems. Proceedings of InfoVis 2004, IEEE Symposium on Information Visualization, Austin, TX, 9-16.http://www.ics.uci.edu/~kobsa/papers/2004-InfoVis-kobsa.pdf
- Layout of Multiple Views for Volume Visualization: A User Study, Daniel Lewis, Steve Haroz, and Kwan-Liu Ma, Proceedings of International Symposium on Visual Computing, November 6-8, 2006, pp. 215-226. http://www.cs.ucdavis.edu/~ma/papers/isvc06.pdf
This is a small sampling of some excellent user evaluation papers that are out there. I would request readers to comment on these and add more user study related papers that I may have missed. Please let me know your thoughts on conducting a user study and share your experience if you have any interesting ones.
Ever since I’ve been involved with visualization, the two factions in the visualization community have fascinated and amused me. Scientific visualization deals with visualizing data that has inherent structure such as medical, hurricane, CFD data and so on. Information visualization deals with visualizing data that does not have an inherent structure such as financial stock market data, census data, genetic data and so on.
On attending many editions of the Annual IEEE Visualization and IEEE InfoVis (Information Visualization) conferences, I found that they are two entirely separate entities. The set of people organizing, attending and involved one conference is almost disjoint from the other set. There are some practitioners and researchers who keenly attend and participate in both versions but they are far and few in between.
The Visualization community isnt unaware of this strange but interesting divide.
They have had two panels, one in 2004 and another one in 2006 to discuss this divide and examine the pros and cons.
In 2003, the topic was “Information and scientific visualization: Separate but equal or happy together at last?” with leading experts from both fields pitching in.
- Theresa-Marie Rhyne, North Carolina State University
- Melanie Tory, Simon Fraser University
- Tamara Munzner, University of British Columbia
- Matt Ward, Worcester Polytechnic Institute
- Chris Johnson, University of Utah
- David H. Laidlaw, Brown University
At the IEEE Visualization 2006 conference held in Baltimore, MD there was another panel. This was organized by Dr. Helwig Hauser and was aptly called SciVis, InfoVis – Bridging the Community Divide?!
Top researchers from both factions presented their point of view. The panelists were
- Daniel Weiskopf, Simon Fraser University
- Kwan-Liu Ma, UC Davis
- Jarke J. van Wijk, Technische Universiteit Eindhoven
- Robert Kosara, UNC Charlotte and
- Helwig Hauser, VRVIS Research Center
I have taken courses in Visualization that have included both SciVis and InfoVis papers and believe that they both fall under the umbrella of “Visualization” anyway. Personally, I think that having two conferences improves the number of excellent papers that a researcher can read, but I still believe that we are all conducting research to provide insight to application domain users using innovative visualization techniques.
Comments and thoughts are welcome.
1. Researchers at IBM Research in Cambridge, MA have developed an excellent online tool to facilitate easy visualization of data. One can upload their data and experiment with different visualization techniques that are built into the system.
The site is called Many Eyes and here is the link to it http://services.alphaworks.ibm.com/manyeyes/app
2. One of my all time favorite visualization sites has been visualcomplexity.com. Its such an easy to use site with interesting visualizations from diverse fields ranging from biology, business networks, world wide web and so on. They also have a great feature that allows you to look at visualizations that are similar to one another from various fields. On clicking on the “Method” tab at the top, one can pick from one of many different techniques such as radial convergence, arc diagrams, trees and so on.
3. Dr. Ben Shneiderman’s “Information Visualization” class assembles a Vis4All
page that has links to interesting visualizations that were found by his students. Its always interesting to find something like treemaps being used successfully for another new application or some company using graph layouts to facilitate easy navigation for customers on their website.
We need many more such amazing endeavors to help other fields with the power of visualization.
I was looking for some interesting blogs on visualization and found very few.
Here is a list of some that I have found. I may have missed some, so please feel free to write a comment and add some more.
Prof. T.J. Jankun Kelly and his lab at Mississippi State have an excellent blog which is frequently updated. Click here to look at their blog.
Prof. Robert Kosara from University of North Carolina at Charlotte has another interesting and fairly regularly updated blog called Eager Eyes. He has a new series called “list of influences” where he requests famous visualization researchers to list a few of their influences. Influences could be in the form of books, papers and other media.
Infosthetics is a great blog that deals with a wide variety of applications of visualizations that are found on the web.
Matt Hurst at Microsoft’s Live Labs is one of the few people harnessing the power of visualization to deal with the new challenges presented by the data in social media such as blogs. He has an exciting blogwhere he catalogs the use of visualization in the field of social media (blogs, twitters, google trends and so on).
I was not able to find any more blogs that are focused on visualization. If any of you are able to find any blogs that I may have missed, please feel free to add some comments.
Through this blog I hope to present some work that I think is interesting and showcases the power of visualization.