Fighting with computers

This year we've got for Christmas our very first home robot. I was a bit reluctant to buy an expensive item just to figure out later it might work elsewhere but not at our home. This has not been the case. Since day one, our Roomba performed nicely and the only trouble we've got is that it does not like our low-profile doorstoppers. We've made the comparison between them amount of dirt picked up by us and the one we remove from Roomba. I've to say the robot wins in the "who picked more dirt" game. The only extra work we're doing in preparation for Roomba to clean a room is to remove as many objects as possible that might interfere (i.e. chairs, trash bins, etc). I'd say it's been money well spent (as far as the robot keeps the performance level for a couple of years). What is a plus is that the robot may return to the charge station by itself (sometimes) when battery needs to be recharged. I'd day this is not a feature to trust on, as I'm a...

No, geo-tagging is not a built-in feature on Canon Powershot S95. However, there is an interesting technology for doing that with your favourite camera. I was introduced to that three years ago by googler Mano Marks (of AppEngine fame) but I was not too impressed at the time (as I was not sure how to store that info). However, once I started using iPhoto I saw that application was aware of geo-location information and therefore it could be useful to have it in my pictures. This Christmas I've got a 2GB Geo Eye-Fi SD card as a present. I'm happy to report that it works nicely with my Powershot S95, where each image is shown as uploaded or not uploaded by means of an icon (Eye-Fi cards can wirelessly upload your pictures using wifi networks). Uploaded images contain geo-location information, so when you import them into iPhoto they will include location information on where each picture was taken. This cards use the same Skyhook database used by other devices to pinpoint locat...

As shown in the video above I have been working on an algorithm to extract a person's silhouette for an arts installation I am working on. The main idea is to use the depth map provided by Microsoft's Kinect so only a small range of distances are used to identify the person standing on a certain spot marked on the floor. By discarding those pixels that are too far away and those too close what is left is the person or other obstacles placed a that desired distance from the camera. It is a bit tricky to make depth and RGB cameras to match exactly the same image (as they are located a few inches apart) so video shows some discrepancy between the dancing user and the drawn contour line. Code was written in Processing using Daniel Shiffman's kinect library for Macs, OpenCV library and MovieMaker library to create an output video file of the action. In the mean time I was developing this, Daniel updated his library and some changes were needed. Unfortunately, OpenCV for Proces...

It's been half a year since Canon PowerShot S95 appeared. Today I'm happy to learn that together with a software update to the "crashy" iPhoto '11 comes a software update for new cameras on Snow Leopard .

I was learning OpenCV for a new art project, but then I learned that the new Microsoft Kinect device had been hacked by a Spanish student after the bounty offered by Adafruit Technologies . This news changed it all, as Kinect drivers for several platforms were made available. I needed to extract the silhouette of a person from the exhibit space and having a depth image as the one Kinect provides made my job ten times easier. The previous plan was to keep an image of the background and substract the current frame from it to detect changes. But handling changes in lighting conditions was a bit challenging. What Kinect provides is a regular color (or infrared) webcam plus a second camera that measures depths (ie. each pixel brightness represents the distance to the kinect of that scene point). If you want to isolate object from an scene that are at a certain distance from the camera, all you need to mark those pixels between a certain value range on the depth image. Simple,...

I had some funds to kill and I thought a new small laptop running Windows 7 would help me not to be a total illiterate when it comes to whatever changes come with W7. I wanted to replace my old Acer Travelamte 3002 WTMi that served me well (though loudspeakers failed almost from day one). A quick look around the web showed that Dell M101z model could be a good choice: good value, acceptable battery time, small and not too heavy. I've never bought from Dell before but I guessed it won't be difficult or unpleasant: I was wrong. First of all, I wanted Dell to produce an invoice to the name of my employer. I contacted with Dell chat (sorry, not available over the weekend) and I asked them for help. I was provided an email of a Dell representative dealing with my employer. I sent her an email and waited. After 24h with no answer, I contacted Dell chat again asking how long should I wait to get an answer, as this being my first time with Dell I was not aware of what the typical servi...

A recent art project requires to do some image processing. This topic is a bit away of what I use to do so I asked around what was available now. Some people suggested me to use OpenCV , which is an open library for Computer Vision projects. I realized that Processing also had some basic features for real-time image capture. Even better, I learned that there was a version of OpenCV available for Processing . The reason of using OpenCV from Processing instead of directly programming in C++ is the easy setup you have with processing. If you have a PC or Mac the use of the system webcam is very easy. For Linux systems it is slightly more complicated. OpenCV makes very easy to do thinks like detecting faces on the image, which is quite funny. There is this book about OpenCV too.

Once I realized I needed to sync my iPad to pass every tiny file to it though iTunes I was not happy. So when I learned there was a Dropbox version for it that was free I saw an opportunity. Later, I found out that there were dropbox versions available for Linux, OSX and, of course, for Windows. A bit later, I learned that even there is an app for my trusty Nokia E71 so I can upload picture to a dropbox folder right away. Since then I've almost stopped using a USB pendrive in favor of dropbox and till now, the server has been great. In a nutshell dropbox is a shared folder on the web plus an app on each computer that syncs the content of your local folder with the copy held on the Internet. Any file you add or change is modified on the network storage. To put the icing on the cake there is also a web-based access to your data, so if you're visiting a friend or using a lab computer you cannot install software on, you still can access your dropbox account files. Basic service is...

One of the features that came with Java 6 is this neat trick: You can have a Javascript runtime on your Java program. You feed it with Javascript code and you can get the value of the variables. It looks great if you need to use some logic already encoded with Javascript and you need to include it in your Java program. No rewriting is needed then. I've done a sample program to evalaute a simple arithmetic expression as the first command line parameter of this Java program .

Just for testing it I installed the new iLife'11 on one of my systems. I mostly use iPhoto and I was happy with iLife'09. What I can see now is that iPhoto look has changed to be more similar to iMovie on the user interface. Some floating menus (like photo adjustment) are not embedded on the application window and general look is worse IMHO. But this is not the only problem. Calendars are no longer available on iPhoto, so it seems they will be back soon . The worst thing, however, happened when I was using the new iPhoto: Suddenly my system stopped responding to mouse click or keyboard. Pointer still moved with the mouse but that was it. I suspend the system and when restarted I've just got a blue screen. I power it off by holding the power button for a few seconds. On the next power up they system asked me if I wanted to send a report to Apple, which I did. Whether this was caused by the new version of iLife or not, I do not know. But my system has been running rock solid ...

Remote access is a cool feature, whether you are (still?) using telnet to remote desktop protocol it is something that is very useful. If you are like me, from time to time you get a phone call from a friend asking for help. Of course her explanations hardly match what you picture in your mind, so many times you cannot help them. If you plan on supporting someone online you can install and configure the computer and networking gear (broadband router?) so you'll be able to connect to that system in the future when there is trouble. Many different solutions can be used, but most of them are OS-dependent. You can do lots of cool things with SSH but mostly on a Linux or OS X system. Microsoft includes the RDP tool for remote desktop access to Windows computers. I've heard about TeamViewer before from a client, but given it was a Windows-only solution I did not pay many attention at the moment. I've recently learned that many interesting choices were available: iPad & iPod ...

I recently learned about an embedded design contest jointly organized by Circuit Cellar Magazine and NXP and mbed . I signed in and I've got lucky as I've got one of the free development units. Having used Arduino platform before I was curious about how easy this thing would be. Fear no more, I was setup in a moment. The funny thing developing with mbed is twofold: On the one hand, your computer will see a new flash storage drive when you plug in mbed. On the other hand, no compiler is installed on your computer. Instead, you use the mbed web. They host the compiler through a web interface. Once your code is compiled you just download the binary code to the flash drive and (now Arduino fans can smile) you manually press reset button for your code to be run. I guess many complaints can be made if you dissect the service EULA, but definitely this way of working comes with many advantages too. Being multi-platform is not one of the least important ones. Now I have to think abou...

I've been using computers for quite a while and one of the things I like is to play with them. Since Apple moved away from PowerPC processors to Intel x86 processors many people thought we will soon have OS X on our PC hardware. Being Apple a hardware company, they have few reasons to make that happen (or so they think and act upon). A few attempts from small hardware manufacturers of offering hardware that allows the install of OS X have faced a lawsuit that more or less kicked them out of business. Some other people just made that same thing just for fun. What they call hackintosh computers are PCs running OS X that has been install after a more or less "hide and seek" game with several DVDs. You need determination and the right hardware to get it working. Many times, a software update prevents your system to boot up next time. As a challenge it might be fun, but there is no fun on discovering your work is buried inside a system you can no longer boot-up. So the use...

I liked the idea of a new tracking device. I guess some time using the iPad gave me the wrong idea on what it could feel like to have a similar interface as a mouse replacement. The same day I received an email from Apple stating the new Magic Trackpad was available I rang a local shop to see if they have it. I was told that because it was announced today they did not have it. That I should wait a few weeks before they would have it. Weird. Anyway, after the summer holidays I wanted to switch one of our iMacs to wireless keyboard and mouse so after being turned down in one Apple shop (a different one), where again I was told I will still have to wait an unknown amount of time (not very helpful direction). Hopefully, I stopped by a third shop where I bought a Bluetooth keyboard and a Magic Trackpad. Trackpad is ok but not magic. For the same money I would suggest anyone to go for a Magic Mouse. It is not that the trackpad does not work, but I've found much more convenient to use the...

The Canon PowerShot S90 I've bought a few months ago had a problem . I had to sent it back to Canon to be serviced. I was unlucky and after more than two months waiting I complained to Canon. It transpired that a new part was needed for the repair. My long wait was rewarded with a brand-new PowerShot S95 instead. Even the seller (I bought it on eBay) was so ashamed about me waiting that long that gave away a 4GB SD memory too. Have a look at this analysis .

I was very excited by what this company was about to deliver. But unfortunately they have cancelled the launch of their QUE electronic ink device. In the mean time, Amazon and Barnes & Noble get into price fight that drove down the prices of their entry-line ebook readers to around $140. This is around halve of the original price and what is better, more features are added to the new devices (ie: wifi). I really like the new Kindle 3 and over the summer I've been reading a lot on my 6" Papyre ebook reader. I've come to the conclusion that 6" is more convenient than the larger size of Kindle DX for reading novels. I'm kind of disappointed with KDX as it is not good for letter-size documents (or A4-size) in my opinion. I've used a lot our iPad over the summer but just for browsing and, more importantly, to use the Maps application to find where to have dinner or to look for the route to a destination (very handy when travelling). However I've read no...

A few days ago I received a letter from Amazon stating a new firmware was available for Kindle, and that those with coverage problems with Whispernet could get the update file from the web too. Firmware update for Kindle is supposed to be quite a straightforward operation. First, update file is downloaded to your Kindle, either wirelessly or manually by the user, to the main folder of the system. Once in there, either because user request or automatically, update process starts. I've done this before and no trouble happened then. This time was different, though. I mentioned on a previous post that I've played with the USB networking hack, that enables network access to the Linux system running in the Kindle. I did some tests, set the correct system time on my Kindle and forgot about it. Now that I was trying to update from version 2.3.4 to the new 2.5.2 version I was stucked. Update process stated normally, and "stage 1 of 3" was shown on the lower right corner of the...

I've been researching the topic of how to get prepaid data cards for an upcoming trip to Finland. It is said that Finland is one of the cheapest and most competitive wireless communications markets. Contrary to most people, I just need a temporary solution to get our iPad working while on the go. While most hotels and cities (i.e. Oulu) do have free wifi, I was looking for an alternative to the outrageous roaming cost of Movistar (from 4 to 10 EUR per megabit). Saunalahti offers a seven-day 4 Mbps data plan for 6.90 EUR. I thought my problem was solved. But just in case, I asked customer service. I learned two things that were a problem: In order to activate the card an SMS had to be sent. Unfortunately, sending an SMS is not one of the things Apple decided you're entitled to do with your iPad. Saunalahti is reserving microSIM cards for contract customers, so if you want pre-paid and microSIM you're out of luck with them. (Apparently you might get lucky in an...

I'm a subscriber (and sometimes an author too) of Circuit Cellar magazine. I use to buy it in print format but a few years ago they made the switch to electronic format. Despite the well-know blues about piracy, they chose PDF files with no particular DRM built in. Since then I'm a paying customer. While I was disappointed with the way the PDF was rendered on Kindle DX, I'm happily surprised that the magazine looks quite nice on iPad. And given the zoom capabilities and the instantaneous response of the device to pan actions I can say it is a very nice experience to read the magazine with it. The only caveat is that sometimes it freezes for a while when browsing the pages quickly. I guess it takes a while to render next page and iPad has limited both computing power and RAM memory. How to get the PDF file on the iPad is also not obvious. Though there are several PDF viewers for iPad, the ones I've tried do not allow me to add the files I want to view. However, iTunes so...

I've been reluctant to give in to the latest Apple gizmo. I tried it out last week and it was ok. Web browsing was smooth and comfortable till you reach a flash based page (flash does not work out of the box). The best feature I noticed was that it dos not get hot. This is very nice when the weather is hot. Writting tris entry using iPad keyboad proved not to be very convenient, as many words get replaced by others guessed by Safari to be what I want to write. Maybe it is causes by a mismatch between my localization and writing in English here. A simple post like this took me ten minutes and lots of backspace.