As I said in this series’ previous post, the Ankara visit didn’t go as planned. Our plan was to visit the city during the day and take the night train to Istanbul. I had read that the night train was really something to try so as soon as we arrived at Ankara we headed for the train station to buy the night train’s tickets and guess what… the wonderful night train was full!
Those were bad news, so after talking with Helena, we came to the conclusion that the best plan was to go to Istanbul on the next train. Of course, we didn’t have a place to stay at Istanbul and we would arrive there late that same night.

(217 Km per second!? Actually the s stands for saat: hour)

Fortunately I had written down the phone number of the hotel I had booked for the day after that one. I bought a public phone card, called them and, to our relief, they had a free room for that night. Now all we had to do was to wait a few hours for our train to Istanbul and we stayed at the station during that time because we couldn’t risk missing the train (and Ankara doesn’t really seem to have much to see, I was pretty much only interested in visiting the Atatürk Mausoleum).
Finally the train came, it would be another long trip and we would arrive late (at 11pm supposedly) but Helena and I had our first dinner ever at a train (at the train’s restaurant, that is), so it wasn’t all bad.

Late night adventures

What’s the worst you can do when you already know you’ll arrive late at the wrong side of the city (wrong continent, actually) and you’re pretty much confident of your travelling Turkish language skills? Hop off on the wrong station, of course!
The problem was that I was worried that we arrived too late to get the last ferry boat from the Asian shore to the European one (where our hotel was, in Sultanahmet) and I thought I heard the train announcement saying we had just arrived at Haydarpaşa (our destination)…
So we hopped off and it took us some long 5 minutes to realize I was wrong. Now I was getting nervous, I didn’t know how far from Istanbul we were, nobody seemed to speak English enough to understand me and the pride I had in having learned some Turkish was gone, leaving a trail of shame. After being told there was still a train to Istanbul that night, we bought new tickets and went to the platform.
When the train came, it resembled a subway one, with open space but dark, we also realized it was more than 10 stops until Haydarpaşa…

(Haydarpaşa train station)

Finally we arrived safely at the train station and now there was another challenge for us to face: how to get the other shore.
It was almost midnight and we didn’t know when the last ferry to the other shore departed so we asked one of the passengers that was leaving the train station like us and he told us we needed to rush because we had perhaps 10 minutes or so to catch the ferry. We were so tired that we gave up on that idea and instead decided to take a cab. The designated cab driver didn’t speak much English so another driver helped us with the negotiation. The price was 40 TRL (~20 €) to take us to our hotel in Sultanahmet, I still had energy to bargain but the driver was inflexible, “40 lira it is!” I said.
The drive took about 40 minutes to get to Sultanahmet (the area) but as soon as we got there, he stopped and said “Okay, here. Sultanahmet!”. I told him that our hotel was still too far for us to walk with two big backpacks and reminded him that I had explicitly negotiated the price to get to the hotel, not the area. He said “okay” and drove around a little more, stopping every once in a while asking other taxi drivers for the hotel’s street (I kept telling him where it was and I had a map but he wouldn’t look at it). This lasted for 20 minutes or so until he found our hotel. When I reached my wallet to pay him, I said “40 lira, thank you!” and he said “thank you, but 40 lira Sultanahmet, please 10 lira more”, I said no-way, it wasn’t my fault he decided to take us to a destination he didn’t know and I tried to explain this to him. He said he had driven around so much that the 40 lira would not make it; “5 lira more!” he said with a lost puppy face and I gave in, took out a 5 lira bill thinking “it is just 2.5 € anyway…” and gave it to him; he said “okay, now 10 lira more”, “WHAT!?”, “10 lira more” he said. I wouldn’t take it, I felt bad that I was fighting over a couple of euros but the fact is that it was indeed his fault, he didn’t know where the hotel was, he didn’t use the taximeter and this sort of extortion was even advertised in our guide book so I took back the 5 lira from his hand, repeated my point a couple of times and headed to the hotel leaving him entering the cab while giving me a look not so much of a lost puppy but rather of an angered pitbull…

Grand shopping at the Grand Bazaar

The next morning we had breakfast at the terrace of our hotel, Hotel Deniz. The breakfast was nothing special but the view over the sea was great. That day, June 24th, we went to the Grand Bazaar to do some real shopping this time. We got there early and it was really funny because every time we discussed or asked about the price of something, we were told “because you’re my first customer today, I have a special price for you”. Of course this was bullshit and we still had to bargain everything
Bargaining is funny, there were a couple of unsuccessful deals (as in, the salesmen would not give in) but we always got a good enough price. Helena was astonished by all the materials, both in quantity and in variety, she could find for making her crafts.
Among other things, we bought:
- A Turkish coffee can;
- Several “evil eye” key-chains;
- Handkerchiefs;
- Leather “Hugo Boss” shoes (the ones I’m wearing right now );
- A purse for my mother;
- A lamp made of tiny glass tiles;
- A traditional, hand-made flute for my brother;
- Turkish delight boxes (lokum);
- A traditional dagger replica;
- Purple “Converse All Star” shoes for Helena;
…

Helena bought these All Star shoes for 30 TRL (~15 €) and in purple, the color she loves and couldn’t find before. However, when we arrived at the hotel, we realized that one of the shoes didn’t have the Converse logo… Helena really loved the shoes so we headed back to the bazaar and found the salesman (just a boy, actually) who looked very embarrassed and swore he hadn’t sold those one purpose (I believed him). He made a phone call and soon after somebody came with a new, perfect pair.

Sightseeing and relaxing again

The Grand Bazaar is an amazing and hypnotizing place but we also did more than shopping for these last days. We went on trip up the Bosphorus where I took some nice photos despite the rainy day and when it finished, we ate a balık ekmek (fish sandwich) at a place under the Galata bridge. After that, we crossed the bridge by foot to visit Galata. This district seemed more urban (as in “European urban”) than the other two shores we had been at. We also passed by a jazz café that our Brazilian friends had told us about back in Cappadocia but we didn’t enter which was a pity because later that night, while at the Marmara Café, we found the Americans we also met at Capadocia and they told us they were there, at the jazz place, together with the Brazilians…

These last days we also found a really good restaurant in Sultanhamet. It is called Doy-Doy and we loved it so much we went there twice. The restaurant is in fact a building with several stories and we had dinner at the terrace. What is also incredible is that the kitchen is at the ground floor and there’s no elevator (not even a food elevator) so one of the waiters goes up and down all night. The price is good, the food is marvelous and the views of the Blue Mosque make it only more awesome. Go there if you have a chance.

We also passed by a famous calligraphist close to the Çemberlitaş Hamamı where I bought a plate with “Família Rocha” written on it for my mom. I know the calligraphist had a webpage that I once visited but I cannot remember what the shop’s name was, my attempts to find it on Google were unsuccessful as well but you can see his picture below. Still, it is easy to find if you pass by the Hamamı and is worth to go there instead of a street calligraphist as this guy is much better.

Hoşça kal

On the June 27th 2011 we boarded on a plane back to Spain. We loved Turkey, its people, its food and its beautiful landscapes and culture. I hope we go back at some point and I totally recommend it if you want a mixture of European and Middle-east cultures.

This finishes the series of articles about our Two Weeks in Turkey in the summer of 2011. Just like the Interrail series, it took me almost a year to wrap it up but hopefully I covered most of our little adventures in this amazing country.

Until the next trip!

Having participated in the organization of events during the University, I’m always happy to see these initiatives taking place.
It was also great to spend a couple of days with the folks at my University and meet with old friends.

About the talks, Thomas gave an overview of gPodder and the infrastructure used to manage the project. Lucas gave a really nice talk about what Mozilla is, what it does and why you should care; because of it, I ended up installing Firefox Mobile nightly build for Android and it has improved a LOT.
My friend Luís Rodrigues (no blog because he’s a badass) talked about CERN, where he works. What an amazing place! He talked about how much CERN uses Python and Django to manage their data. As a Python lover, this makes me really happy.

This was also the first time I presented Skeltrack, my latest creation inside Igalia. Presenting such an algorithm is not an easy job so I took mental notes about what to improve the next time (which will be at LinuxTag) but I was happy that people made good questions about it.

I’d like to thank to the AAUE (Students Association) for the great time we all spent in there.

Presentation slides :

Fortunately, OCRFeeder has some users and contributors who did test it and warned me about some issues, which should be solved in this release.

Take a look at the short list of changes if you wanna see what’s solved and enjoy OCRFeeder.

Source Tarball
Git
Bugzilla

Still, one thing is to have the simple demo of drawing a sort of stick man from one’s joints like shown in the Skeltrack’s example video, another is to actually do something more useful with it. This is the way to check how reliable the library is, so Igalia has built a prototype that consists of controlling the GNOME 3 desktop or even playing some racing games using gestures that are interpreted from the positions of the joints that Skeltrack gives.

It uses one or both hands to control the mouse pointer, perform clicks, drag things around and it even simulates a pinch gesture which adjusts the zoom level. Hands can be also interpreted as if holding a steering wheel, making racing games so much fun.

The results are shown in the following video:

(direct link to video in Vimeo)

Just like pretty much everything we do at Igalia, this demo is also Free Software, so you can get its code from GitHub (check the README to see what the gestures are and what they do), tweak it to your needs or, if you need specialized help, you can always hire us.

The most famous solutions (or the only ones) to do so are the Microsoft Kinect SDK or the OpenNI framework. If you are looking for a Free software solution though, you are out of luck. Microsoft’s SDK, apart from obviously being close, does not even allow a commercial use of it which is something the OpenNI framework does but this is as far as the meaning of the word “open” in OpenNI goes… You cannot adapt/improve their code nor learn from it. To solve this problem, Igalia has just created Skeltrack.

Free Software Skeleton Tracking

Skeltrack is a Free and Open Source Software library whose goal is to provide easy to use human skeleton tracking.
Skeltrack’s implementation was based on a paper by Andreas Baak but, apart from other internal differences, it doesn’t use a pose database. This means that the skeleton joints extraction is based on mathematics and heuristics, no calibration pose nor pose database is needed.

It provides an asynchronous API written in GLib, supports single user tracking (one skeleton only) and tracks up to 7 joints currently: head, shoulders, elbows and hands.

Take a look at the video below to get an idea of what it can do:

(watch it in Vimeo)

How to use it

We took a more modular approach than the two projects mentioned above. This means that Skeltrack expects to be given a depth buffer (i.e. depth image from the Kinect) with nothing but the user on it as opposed to connecting directly to a Kinect device.
Still, three easy steps should be all that is needed for Skeltrack to be ready to use:
1) Use the GFreenect library we released a couple of months ago, connect to the depth stream signal and get the depth buffer;
2) If there are other objects (chairs, tables, walls, etc.) apart from the user, then these should be removed by performing background subtraction or by excluding everything that is out of a threshold;
2) Skeltrack performs some calculations that might be heavy depending on the machine and the buffer size so users should reduce the size of the buffer that is given to Skeltrack by using its dimension-reduction property as the reduction factor.

Take a look at the test-kinect example (shown in the video) shipped with Skeltrack where the steps above are implemented.
The documentation for the project is available here.

Skeltrack is in its early beginnings and we want to detect more skeleton joints and work on stabilizing the results so, its features and API might change in the future.

Feel free to get the code, file bugs and send patches at its GitHub repository.
Hopefully more people will contribute to it until we finally have a rock solid, easy to use, Free Software skeleton tracking library.

I need to thank Søren Hauberg who was kind enough to point me in the right direction when I needed.