EuroVis 2011

I’ve written before about EuroVis, the most important European scientific conference on visualisation. In 2009, it took place in Berlin, in 2010 it was in Bordeaux, and, an a surprise non-twist of alliteration, the 2011 edition was held in Bergen, Norway. With 216 attendees and a practically perfect organization, this year’s edition has been described as the biggest and the best EuroVis ever. In a bid to save some time (I still owe you a mega-edition of the Weekly (actually Monthly) Head Voices), I’m going to give my biased account in bullet-list form:

  • On Tuesday evening, we were welcomed by the very charismatic vice mayor of Bergen in the Tårnsalen of the Lysverket building of the Bergen Art Museum. It seems the photo I took of the inside of the art deco tower, built in 1938, is quite a popular shot. The food was divine, thank you very much.
Art Deco tower from the inside in the Tårnsalen, Lysverket.
  • The next morning, during the conference opening, the following Bergen (rainiest city in Europe) joke was told: A visitor asks a local boy in exasperation “Does it rain like this all the time?” and the little boy answers “I don’t know, I’m only 12 years old!”.
  • The conference keynote was given by Scott McCloud, American cartoonist and comic theorist, on aspects of visual communication. This was most probably the best presentation I’ve ever had the privilege of experiencing. Besides brilliant oratorship, his slides are somehow more a visual stream of consciousness affair than discrete quanta of information. When I grow up, I’m going to present like that.

As per usual, I get to award the Weekly Head Voices Best Paper awards, and they go to the following papers:

  • A Shader Framework for Rapid Prototyping of GPU-Based Volume Rendering by Christian Rieder, Stephan Palmer, Florian Link and Horst K. Hahn. Rieder and his colleagues have constructed a full GPU-based volume rendering pipeline in MeVisLab of which the various shader based components are modifiable at runtime. This means that you can prototype your GPU-based volume rendering ideas in no time flat!
  • Curve Density Estimates by Ove Daae Lampe and Helwig Hauser. Back to basics and really important work on the effective visualisation of complex curves at any resolution, with smooth scaling between levels.
  • A Gradient-Based Comparison Measure for Visual Analysis of Multifield Data by Suthambhara Nagaraj, Vijay Natarajan and Ravi S. Nanjundiah. Another back-to-basics paper in which the authors show how to find the agreement between hundreds of scalar fields and visualise this agreement, thus enabling comparison.

The slightly less prestigious EuroVis 2011 Best Paper awards went to:

  1. Uncertainty-Aware Exploration of Continuous Parameter Spaces Using Multivariate Prediction  by Wolfgang Berger, Harald Piringer, Peter Filzmoser, Eduard Gröller. I was unfortunately in the other session, but was told by numerous colleagues that this was indeed an award-winning presentation as well.
  2. A User Study of Visualization Effectiveness Using EEG and Cognitive Load by Erik Anderson, Kristin Potter, Laura Matzen, Jason Shepherd, Gilbert Preston, Claudio Silva. This was presented in the Evaluation session which I had the privilege of chairing. It is indeed a very compelling idea to measure the effectiveness of a visualisation through cognitive load and this paper documents the first very important steps in this direction.
  3. A Gradient-Based Comparison Measure for Visual Analysis of Multifield Data by Suthambhara Nagaraj, Vijay Natarajan and Ravi S. Nanjundiah. This was also amongst the more prestigious WHV best paper award winners, see above!

The rest of the conference featured the following bullets:

  • During the social event on Thursday evening, Frits Post (my boss), was elevated to the rank of Eurographics Honorary Fellow, recognizing his service to and standing in the visualisation community. Including this newest addition, there are only five (5!) EG Honorary Fellows in the world today. I am very proud!
  • During the first session of the morning after the social event, I had the exquisite privilege of presenting the work of my Brazilian colleagues: Piecewise Laplacian-based Projection for Interactive Data Exploration and Organization by Fernando V. Paulovich, Danilo M. Eler, Jorge Poco, Charl P. Botha, Rosane Minghim, Luis G. Nonato. I really do like presenting at events like these, and it’s been a while. Do read and cite the paper, it documents a practical way of reducing any set of high-dimensional data points to the visual space, and enabling interaction with those points on the visual space!
  • The capstone of the conference was presented by the legendary Prof. E. Gröller, also known by the whole community as Meister. In typical style, the title of his talk was only announced during the talk itself. The title was The Haunted Swamps of Heuristics. In this philosophical and visionary contribution, it was argued that algorithms and parameters are too deeply intertwined to focus only on the former, but that it was more important to study, in detail, the exact behaviour of the latter. More broadly speaking, we need to accept the fact that there is a great deal of uncertainty also in the parameter spaces of our algorithms, but that this uncertainty can and should be dealt with correctly.

That thought-provoking capstone and this blog post will share the same concluding quote:

Doubt is not a pleasant condition, but certainty is absurd. — Voltaire / Gröller

I hope to see you in the comments below! You could also opt to click on my shiny new +1 button, or my slightly older but no less shiny retweet or facebook share buttons.

On the importance of taking notes. [Weekly Head Voices #38]

Post summary: Part one is about friends graduating from Evil School, part two is rather short mentioning vague bits of good news and part three is 100% time management and productivity boosting goodness! Feel free to skip, skim or reorder!


On Thursday, February 10, 2011, my dear friend Mister Krekel graduated from Evil School after years of hard work and evil-doing, and will henceforth go through life as the formidable Doctor Krekel. Please do watch out.

Evil School. (Photo by the talented

The joyous transition took place in the Evil School’s Academiegebouw in Leiden, and this time yours truly (I’m referring to me in a round-about fashion) even had the great honour of playing a part in the formal proceedings. If you’re curious as to what exactly this ritual constitutes, see this previous edition of the WHV on the graduation of another terribly evil colleague. I believe that the bunch of us now constitute a bona fide Axis of Evil. No, the evil jokes can unfortunately not stop yet.

The Party was held in a secret cafe nearby. You will notice that I’ve capitalised Party, as it was not your average run of the mill Evil School graduation affair, but a social event of note. Here in Holland, the PhD defence and graduation are a combined affair, and so the whole day is dedicated to just one person. It is actually very special: People take time off from work, sometimes even temporarily put aside their differences, and travel from all over to attend the festivities. It’s like a wedding, except that there’s only one of you. I can only recommend it very highly. At the Party, everyone had clearly read the memo, and they were there with that singular goal in mind: Celebrate the freshly minted Evil Doctor. Presents were given, speeches were held, photos were shown, beer was imbibed and, flying in the face of all advice concerning the mixing of alcohol, cameras and social networking, the best evil photographer in town, who’s coincidentally also in Evil School, took the most amazing photos that you should be able to see on Facebook if you’re one of the privileged few to belong to The Network, also known as The Friends of the Axis of Evil.


On the good news front, you’ll see (or not) on the list of EuroVis 2011 conditional accepts, that a paper by cool colleagues from far away, to which I contributed a small part, has been conditionally accepted, and hence has a significant chance of being presented at said event in Bergen, Norway (May 31 to June 3). We also have plans to submit a poster (or two), so there’s an even more significant chance that I will make an appearance at this fantastic conference! We’re also cooking up various odds and ends that will hopefully crystallise sufficiently by the end of March to be submissible for VisWeek 2011. Cross yer fingers.


Today’s backyard time management section is in fact more about planning than it is about notes. However, my Pro-Tips involve combining them in an easy to implement productivity booster. When people start out in research, one of the first bits of advice they get is keeping some kind of lab journal. I think this advice applies to more than just research: If you do any kind of independent or project work, jotting down your activities, thoughts and results during the day is useful in helping to structure your thought processes, and also very helpful when you have to backtrack a complex multi-day procedure. During my Ph.D., I filled a number of real cardboard-and-paper books with notes. More recently, I’ve started using Google Documents for the same purpose. Besides all the other advantages, having to document explicitly your work output keeps you productive and on your toes.

Pro Tip #1: Keep a lab journal, even if you don’t work in a lab.

I’ve mentioned before that my resolutions for 2011 included more concrete planning. This has manifested in a work-in-progress planning for the whole year, including milestones, awards won, and so forth, but much more practically, it has manifested in a little lab-journal-compatible trick. Every morning when I sit down to begin the day, I spend a few minutes thinking and then start the day’s journal entry by writing down, as concretely as possible, the tasks that I plan to complete by the end of the day. This also ensures that I spend effort on the important things, and not only on the urgent things. So, that brings us to:

Pro Tip #2: At the start of each day, write down in your lab journal exactly and concretely what you plan to accomplish by the end of that day.

These pro tips appear to be quite straight-forward, but together they help one to focus, and to keep tabs on one’s effective productivity. In other words, just being terribly busy the whole day gets you nothing; the trick is being terribly busy in all the right directions.


Somebody is clearly pushing the boundaries of awesomeness… cowboys AND aliens!

EuroVis 2010 [Weekly Head Voices #24]

Welcome all to the latest edition of the Weekly Head Voices!  In a bid to get more numbers into my titles (oh who am I kidding, I’m clearly trying to slightly injure or preferably frighten two birds with a single stone, splitting infinitives as I go along), this WHV is dedicated to the EuroVis 2010 conference, which on its part is the reason I spent most of last week in Bordeaux.

Château Faugères, youngest of the chateaux. Photo by Peter Krekel.

EuroVis is definitely the most important European scientific conference on Visualisation. For detailed and complete coverage, see T.J. Jankun-Kelly’s (he was also the uncontested tweetmaster of the conference) detailed blog posts on the first, second and third days of the conference. The post you are reading now is my very own extremely biased and mostly incomplete view of the conference and of conferences in general, which can sometimes be interesting.  Or just very misleading.

Let’s start with the basics: A scientific conference is where a bunch of mostly scientists get together somewhere in the world, ostensibly to present recent results of their research to each other. Work certainly gets presented, and in some cases it’s a treat seeing a gifted orator giving a superb presentation.

However, in my mind the primary reason to go to a conference is not to discuss work that was submitted half a year ago, but to meet with colleagues and friends and to discuss important things, such as life, science in general and the research that has not yet been published or even started up yet. It is a hugely important element of the social goo that keeps a research field coherent and cooperative.

There are numerous overlapping interest and social groups that continuously split off to discuss something or just socialise, and then merge back into the larger group. The various attendees each has their own character and associated mode of operation: Some flit around, speaking to all and sundry, some stick to and act as the backbone of the subgroup that they belong to, some walk around and think, sometimes being approach by yet another type of agent. It’s interesting to watch from the corner of one’s eye whilst one is also enjoying taking part in this system. Sometimes the backyard anthropologist in me wonders how exactly the nature of this social fabric affects the performance of science. I imagine that it would be cool to put together a taxonomy of social conference types and even map their behaviour during a single conference such as this.

In any case, at EuroVis there were, the same as last year in Berlin, 190 attendees.  Three days of presentations, with a poster session and a visit to Saint-Émilion thrown in for good measure.

With regard to the presentations, I seemed to notice an ever-so-slight upwards trend in the number of papers accompanied by open source software implementations (both MotionVA and ShapeSpaceExplorer by respectively our very own Peter Krekel and Stef Busking are open source, but there were more examples). This is really a great development, as it is an important component of the whole open science idea. With the implementations available, colleagues can reproduce one’s results and thus have a greater chance of being able to improve on them. Also, new implementations can be directly compared to existing ones, something which is currently incredibly hard.

Two of my favourite presentations were the following:

  • Visual Support for Interactive Post-Interventional Assessment of Radiofrequency Ablation Therapy by Christian Rieder, Andreas Weihusen, Christian Schumann, Stephan Zidowitz, Heinz-Otto Peitgen: I really like this genre of solutions, where complex 3D problems are reduced to normalised 2D representations. A previous example is the work of Neugebauer et al. at EuroVis 2009. In this case, the authors presented “tumor maps”, a 2D map-style representation of the tumor and its surroundings which greatly facilitates the post-therapy tumor assessment. The fulltext paper will hopefully be linked on Christian’s website soon.
  • Estimation and Modeling of Actual Numerical Errors in Volume Rendering by Joel Kronander, Jonas Unger, Anders Ynnerman, Torsten Möller: Although this is not my personal favourite type of research, I think the work (and work like it) is tremendously important. The authors meticulously measure the impact of different precision and sampling strategies on the volume rendering pipeline, and, as if that wasn’t enough, derive a mathematical model with which the role of these variables can be predicted in unseen volume rendering problems. In my view, this is a great example of research towards deriving elements of that elusive visualisation theory. Just to help ram the point home, the presentation was extremely well executed.

On a slightly higher level, what I’ve also started noticing is the different styles of visualisation.  Many research groups have a distinct style of visually representing their data: One can easily recognise a Viennese design, and sometimes even notice how elements thereof have been subtly adapted by a faction of ex-Viennese scientists in Bergen.  The Bergenesque style is still quite young, but will probably soon spread to different groups.  Of course not all groups are that easy: Our own style is heterogeneous, although I’m glad to see at least the blue-to-yellow more-or-less perceptually linear colour-scale starting to permeate our work. It would still be interesting to start a kind of genealogical tree showing the various styles and also how they spread along with the persons practising them.

On the topic of Saint-Émilion: 1000 vineyards covering 95% of the available land, oldest of the vineyards 2000 years old, number of beautiful old Chateaux (castles man, castles!) each having on average 6 hectares of land. 5 different classes of wine produceds, ranging from 5 euros per bottle (hello there!) up to 7000 euros per bottle. It’s a beautiful piece of country.  In fact, it reminded me very strongly of the Western Cape in South Africa,where I grew up.

My group ended up visiting Château Faugères, by far the youngest of the chateaux, but awesomely cool nonetheless, as it was designed by a Swiss-Italian architect by the awesomely cool name of Mario Botta. We got to taste one (1) wine. This was slightly less reminiscent of the vineyards of the Western Cape in South Africa, where one can taste wines until one starts developing very entertaining coordination problems. Fortunately, this very small oversight was more than compensated for by the subsequent visit to the town of Saint-Émilion, its monolithic church and the catacombs, all narrated by an extremely gifted and humorous guide, and finally by the marvelous concluding dinner, done as only the French can.

So kids, that it was it for this week’s lecture on Further Mystifying Scientific Conferences!  I have to go, as I have to start thinking about the next Weekly Head Voices.

Weekly Head Voices #18: Refactor my dogfood.

Welcome all, to this, the 18th edition of the Weekly Head Voices, in which I discuss a number of issues that mostly have nothing specific to do with the 11th week of 2010, but which might or might not have crossed my mind during that time! Issues include good news on the EuroVis 2010 front, a new edition of the Head Voices Review featuring my completely unexpected stay in a 7 Tesla MRI scanner (as a test subject, of course)  and finally some nerdy backyard philosophy dealing with the well-known itch to Rewrite Everything From Scratch, Because What’s There Now Sucks.

First, because I have no other visual element for this week’s post, and  because I am, as you might have noticed, a method blogger, I present you with probably the best improv I’ve ever seen so far. For those of you who have been completely asleep the past few weeks, chatroulette is a new site that’s been taking the interwebs by storm. The site pairs up random strangers for webcam chats. One is allowed to move to the next random stranger with the click of a buttom (resulting in the new English verb “to next” someone..). Random hilarity (and often perversity) ensues! Here’s that mostly SFW and brilliant piano improv:

(The original video had to be pulled, after 4 million views, due to some YouTube issues. Merton, pianist, has posted this new version. Thanks to Francois for the heads-up!)

Back to business, we have just heard the great news that our two EuroVis 2010 submissions have been finally accepted for publication.  The articles are:

  1. S. Busking, C.P. Botha, and F.H. Post, “Dynamic Multi-View Exploration of Shape Spaces,” Computer Graphics Forum, 2010.
  2. P.R. Krekel, E.R. Valstar, J. de Groot, F.H. Post, R.G. Nelissen, and C.P. Botha, “Visual Analysis of Multi-Joint Kinematic Data,” Computer Graphics Forum, 2010.

Fantastic work you first authors you! Remember people: YOU HAVE TO CITE THESE SOON, AND YOU HAVE TO CITE THEM OFTEN! This also means that a number of us will be going to Bordeaux in June (I can imagine worse places to go to in June) to mingle with other scientists and to drink really good red wine.

That good news brings us to the influential WHV feature, the Head Voices Review! (My TPN is still working on the new jingle.  Hopefully it’ll be on time for our joint Vodka review feature.) In this edition, I’ll be reviewing the Philips 7 Tesla MRI scanner and the JBL Duet-200 computer speakers.

On Friday, I unexpectedly had the pleasure of trying out a state-of-the-art 7 Tesla Philips MRI scanner, as a test subject. I can report that the bore, although small, is quite comfortable. However, test subjects with claustrophobic tendencies should probably look elsewhere.  Scanning can be quite noisy, especially when a diffusion weighted imaging protocol is applied that involves scanning in 162 different gradient directions (to study the structural connectivity in my brain). However, the music that gets piped in between scanning sessions more than makes up. After scanning, it was scientifically confirmed that there is indeed a brain housed in my skull, an observation that pleasantly surprised me. Soon I hope to be able to post visualisations, made by one of our MedVis ninjas, of the structural connections in my brain.

All in all, if you have a few million euros lying around, this piece of kit is highly recommended.  To summarise:

  • Philips 7T MRI: AWESOME.

In a previous review, I was quite negative about the Logitech S3-30 speakers, for a large part due to the absolute mess of cables that it comes with. This past week I took delivery of the new JBL Duet-200 speakers I ordered, for the grand amount of 30 eurobucks, to replace it. The JBL is a single unit containing two speakers, something which might be seen as a drawback, but which I consider an advantage. In spite of its compact appearance, it packs quite a base and more than sufficient volume.  In addition, there are exactly two (2) cables: One for the power supply, and one for the audio. I can only hope that Logitech contracts JBL on their next PC speaker product design. My only (minor) gripe is that the JBL-supplied audio cable is only about 40cm long. All in all:

  • JBL Duet-200 at € 30 price-point: AWESOME.

MRI scanners and PC speakers: No product too big, no product too small for the Head Voices Review!

Finally, it’s time for some backyard philosophy.  This week, it’s a brief point of really nerdy philosophy, although I think the principles apply to some non-nerdy activities as well. Software developers, as well as many other engineering types, often reach a point during working on a project, when they have a hard-to-control urge to trash the whole thing and start from scratch.  There is usually a very strong belief that the project / software / product can be designed much better by starting from scratch.

It turns out that this is an insidious and mostly incorrect belief, for a large part due to all the knowledge present in the existing “ugly” product that will get thrown out. Engineers easily underestimate the importance of this knowledge. It turns out, much as we don’t like to hear this, that refactoring is, nine times out of ten, a far better answer than rewriting from scratch. Experienced developers know this, and are mostly able to suppress the rewrite from scratch itch.

Joel Spolsky wrote a really good essay on this phenomenon. Go read it!

Weekly Head Voices #13: So you want to sue me?!

In this post, I talk about our latest EuroVis news, give a quick break-down of my activities of the past week whilst turning my productivity glut into a game, sing an ode to DropBox, get threatened with a lawsuit (again) and impart, as per usual, some applied backyard philosophy.

EuroVis 2010 Logo
All hail the beautiful EuroVis 2010 logo!

To kick start this blog post, allow me to get this off my chest: BOTH Stef Busking’s paper on the <CENSORED> and Peter Krekel’s paper on the <CENSORED> were conditionally accepted for EuroVis 2010! There’s some hard work ahead to get the papers ready for the final round, but this conditional acceptance (70% of submitted papers were rejected) is a great achievement. You may send them your webcammed applause and adoration.

During the past week, the 6th of 2010, I did 2 hours of lecture preparation, 3 hours of straight lecturing, 4 hours of demonstrations and 11 hours of scheduled meetings, most of them quite energising. According to my GTD system, I also completed 19 tasks spread over 11 projects. I’m mentioning this here, as I want to increase my weekly task completion count, and posting this on my blog turns it into a weird kind of game. Once again, you are allowed, no you’re encouraged, to boo and hiss at the appropriate moments.

I also finally got around to updating our research group’s publications listing scripts to generate per-paper pages, so that we’ll henceforth have a (hopefully) attractive webpage to go with each published paper. See this for an example of the per-year listing, and this for an example of such a paper page.

Screenshot of example per-paper page.
Screenshot of example per-paper page, click to go there!

On Wednesday, three of us got together at my house to convert a complete PhD thesis (a good one, if I might add, and I’m allowed to, since it’s not my own) from Word to LaTeX, to get it ready for print production. Besides having lots of fun (besides bubbling personalities, beer was also involved), we got to stress-test DropBox by concurrently working on a shared folder filled with .tex files, and often doing full LaTeX builds involving latex, dvips, ps2pdf and bunches of image conversions. In spite of this dangerous concoction of a PhD thesis, concurrent editing, beer, laughter and the cloud, Murphy never arrived at the party and we ended up with 170 pages quite handsomely typeset in LaTeX. Kudos to Dropbox! (and us of course. duh.)

On a slightly less excited note, I’ve just been threatened with a lawsuit for the second time due to activities on my blog. This time, it’s a very angry and foul-mouthed homeopath. If you’re interested, search the latest few comments on my Werner post for the ones made by a certain DJ. Currently I’m hoping he’ll take the reasonable (for both of us) option and stay away. (DJ, if you’re reading this, no this is not THAT promised post. I’m keeping to my end of the deal: You stay away, your identity is safe.)

Continuing a short but promising tradition in backyard philosophy, I’d like to conclude with something I seem to remember a Very Flat Cat telling me years ago, and something that recently came up again in yet another interesting discussion with the same extremely interesting guy from last week’s visualisation science discussion:

Under-promise, then over-deliver.

I’ve seen some pretty good mottos, but this one’s an absolute keeper. Thank you very much Very Flat Cat, also for this.