Thursday, June 26, 2008




well, I got the film back today. The negatives are quite dark to look through (which means they're blocking visible light), just like they should be, but with some tests it's apparent that they're not blocking IR light, sweet! So on with the project:-)
pic 1 is a shot without the visible light filter or the IR filter, so it's seeing both. pic 2 is demonstrating the developed negative. It's clear that it's letting almost all IR light through, but blocking most visible light. pic 3 is a shot with the visible light filter completely over the webcam. Pretty scary! My IR LEDs are really bright, I think I need to lower the current in the circuit to get less light so the software can track one reflective point better.

Wednesday, June 25, 2008

midsommar!

Wow, the summer days are long here. Tonight the sun was shining brightly through our window and I thought "this feels like it's 5:30pm", ...and it's really 9pm! it finally gets dark around 11, but the sky is still lit somewhat through midnight. I'm not used to it. Makes life interesting trying to convince Christina it's time for bed. We have been having our "say goodnight to the outside world" ritual where we go through the apartment and close shades, blinds, turn off lights etc to help her feel like it's time. An interesting contrast to the winter, when I'd leave for work and come home in complete night-time.
Ellinor has been talking a lot more about our summer vacation to Norrland. (must be getting excited about it or something!) I start vacation from work on July 23, and come back on August 25, so that's a good 4.5 weeks. It will be a mix of going to Norrland, going to the Archipelago (the islands along the coast) near Stockholm, and getting some relax time at home as well. Should be nice.
My mouse alternative project is coming along. I'm waiting for the film to develop; should have it friday, then I just need to jerry-rig some foot mouse pedals and voila, no hands! (except for the keyboard of course...)

Friday, June 13, 2008

Being a computer science guy and spending a lot of time on the computer, the past while my arms have been feeling it, and protesting. This got me thinking about alternatives to using a mouse/trackball. I googled "mouse alternatives" and found some interesting products; particularly interesting to me was head tracking. There are some expensive products out there that would probably do the job, but I thought, "hey! I can roll my own setup!" My last semester at UVSC I took a 'digital image processing' class. It was a lot of fun, so I decided maybe I could write a program that does object tracking. I first wanted to poke around and see what free programs were out there, which has lead me into two separate projects:
1. The first is a free windows based app called 'FreeTrack'. It does point tracking based on light emitted from IR LEDs which you attach to your hat or whatever. You modify your webcam by pulling out the IR filter so it actually catches IR light, then you add a visible light filter. The net effect is the webcam is only seeing IR light, so the software then has a much easier time tracking the IR light from the LEDs. So I went to ELFA, got myself some IR LEDs, some resistors, refreshed on the circuit equations I learned in physics, and put together a little IR flashlight that you put up right next to the webcam pointing towards my face. I'm then going to put a little reflective dot on my forehead or something, and voila! for the curious, here are the electronic stats:
3 IR LEDs: 880nM, 150mA max, 25 degree focal range.
1 power supply: outputs 17.25v DC (supposed to be 12V! I had to adjust for this...) 600mA max
4 resistors 60 ohms, .6W max

the equations:
V=IR
P=I(squared)R

I ended up wiring the LEDs in series, so, prototype1 one went alright, worked, but the resistor was getting really hot! this is normal, and it was under it's max power rating (running at .4W), but I housed my little unit in a mini-DV tape holder, so I thought I should find a way to cool it down. Brilliant me wrapped aluminum foil around the resistor as a heatsink (it was 1am mind you)...so I plug it in and think..."wow, the LEDs are getting really hot"...pop, pop! the LEDs burned out, and as soon as they did, I realized my mistake. I accidentally created a circuit bypass around the resistor, so I fried the LEDs.

prototype two: bought a resistor with a higher power rating, so it won't run as hot. did much better with the soldering this time, and whipped out my unit in under an hour. It works great, in fact I think it's putting out too much light, but as soon as I finish the webcam I can test better. The only thing my webcam is lacking is the visible light filter. I bought some ISO 100 film for this, which will be a cheap alternative to the filters made of glass.

2. To help roll my own object tracking on Ubuntu, I found opencv; libraries and such for computer vision stuff. After some headache trying to get it to compile and run (it kept telling me the functions were undefined, even though I knew the libraries were installed) I finally figured out that the linker needed the libraries specified with the -l flag, at the end of the linker command line. yeah, it works now, and I can play around with some of the samples they have and start to use the libs.

fun stuff!

Friday, June 6, 2008

Nighttime with Christina

I want to take the chance to write about this before it slips my memory. I start where it began, when our daughter was born, about 20 months ago. It actually began earlier than that, it was when we visited with a midwife during the prenatal care. I asked about where the baby should sleep, I had heard different opinions on what was "best" for each family. The midwife said her daughter had what they called the "family bed" and seriously discouraged that, since the kids stay there forever!
I took that at face value and we were careful to put our daughter to sleep in her own space. I nursed her until she was almost asleep, then Daniel, who is the gentler of the two of us, carefully moved her to her bed. We did this for maybe four months or so.
To the equation adds that I am the heavier sleeper of the two of us. So when Christina woke up at night, Daniel would wake up first from her crying, and after considerable time screaming, I would finally wake up, unless he first got my attention... So we decided we would move her mattress into our bedroom, and she slept on her mattress next to ours. Nighttime was a lot easier, especially since her once 10-11 hour stretches of sleep during night around 2 months, had become more like 5-8 hour stretches, most often 6 hours. I know there is such great variance with this, it varies even with her from night to night. Sometimes she sleeps solid 8 hours, other times it seems we can only lay down for a few, maybe 3 hours, in one stretch, and then she continues to wake every hour... those are a little hard.
We moved when she was 7 months old, and because temperature was hard to regulate in her room, we kept her with us in our - now much bigger - bed. She soon learned how to properly dismount a bed without hitting the head first (after taking several not so fun blows...)
We traveled a lot when she was 11 months old, for about a month. We tried maybe once to put her in a separate bed, and it lasted less than one night.
We got her a kids bed which is easy to get on and off in our new place, and still tried to get her to sleep there occasionally, (read, that was our goal, usually). However, occasionally thinned out to become "almost never" since she was so much happier in our bed, and almost without exception woke up screaming soon after being laid in her bed.
We started to feel like it was an honor to have her in our bed. I started to treasure the moments when I got to wake up and nurse her. What a change it was! I remember when I was a very new mother, reading somebody else's account about treasuring the nighttime moments. I think I might just start to understand what she meant. Because I now see an end to it all. She has put up with me putting her to sleep in her bed a couple times without fight or screaming. She is the one that says "I'm tired, I want to go to bed" (she signs "bed" by leaning her head to her palm to the side, very sweet), and will nurse to sleep in my arms, but rather in bed, or in her own bed.
Being kicked in the head, or almost kicked out of bed, or snuggled right next to you, finding round sweat spots in the bed where she lay, are sweet memories that won't last forever. What the midwife told me simply isn't true. Kids don't stay in their parents' bed forever. They stay there as long as they are welcome and feel the need for closeness, that's my conviction.
It makes for more family time, even though we are sleeping, and creates more togetherness. She still wakes up screaming every now and then, but not because her parents are nowhere to be found (because her gums hurt, she's wet, or something else). I can observe her when she sleeps more often. Whoever has watched a loved child sleep knows how sweet that feeling is, I think. I can anticipate her waking up, because she takes a while to get into her consciousness. I can watch her stretch her muscles and mouth while she gets into the new day.
*I know there are certain things that make it not a good idea to let small children or babies sleep with you, but we have carefully avoided those (drinking alcohol or taking other strong drugs, being overweight, having an exceedingly soft bedding or a water bed).