Wednesday, May 27, 2009

falling edge

sometimes coming home is the best idea, even if it's a new home.

it's been nearly a week since the last time i legitimately updated this thing, so how about an update?

remember my goals from last week? time got the better of me, and moving took up pretty much my whole weekend.

let's go line by line:
- migrate to a CMake building system -
decided that it was a procrastination idea. good in theory, but since our makefile works, let's not fuck with it. there are two more weeks in the project, and maker faire is this weekend. we need to get something up and working, stat.

- successfully thread blob detectors -
i tried two different approaches to this. the first involved creating a single pthread for each detector, a pthread for stitching, and have the main thread do bloblist sending. the threads were programmed to wait for each other to finish before looping around, so really only the blob detectors were running in parallel, while the stitcher and sender were separated but synchronized sequentially. the idea was to lay the framework for a pipeline without optimizing it. my first stab resulted in deadlock and i spent about a half an hour debugging it before calling it quits that night.

my second approach involved creating and destroying pthreads for each every time around the loop. the approach is obviously less robust, since it introduces the overhead of creating and destroying the threads every time around, but it meant that i could avoid mutexes and not worry about deadlock. it also meant that i was only threading the blob detection. i got it to work, but it appeared to perform worse in that it used the cpu more. matt brought up that this might indicate that it's performing better in that it's processing more frames per second, which would account for the higher cpu usage. that's under the assumption that we're getting what we pay for.

ultimately, i had to put this on the backburner so we have something to show at maker faire.

- finish hacking up the cameras we have and see about putting as many of those as we can in the table

just finished this today. bought 2 cameras from best buy, one from gamestop, and left one on hold at the other gamestop, unreasonably located less than a mile from the first. if anyone else was trying to get a ps3 eye webcam today in santa cruz, it's safe to say they had quite a hard time, considering what i bought was all of the stock at both locations i visited. i also cut my finger pretty mean on our janky rusty-looking dull ass xacto knife. eddie warned me. i didn't listen.

- bezel, if it arrives

still hasn't arrived. jas needs to call mcmaster carr tomorrow.

- ask dilad if/when they shipped the screen / tracking number

the dilad screen arrived friday, damaged during shipping. thankfully, michael from tcl in vancouver was readily available by phone and email, so we were able to send some pictures and figure out the best course of action for our project. the problem was that the tube had buckled in the middle, denting the rolled screen. the dent left a mark that repeated a few times down the length of the screen. michael advised us to proceed with the applying the screen since it wouldn't make sense for us to send it back and there was the off chance that it would still work. it didn't, and the dents showed up as dark spots in the projection. conveniently, monday wasn't a holiday in canada, so we received a shipment today of another roll, this time the same tube was double boxed as well. it was definitely appropriate -- neither of us wanted this to happen again, but comical nonetheless. there was enough undamaged screen from the first shipment to apply to the prototype without any wrinkles, and the results are pretty spectacular. the screen is completely visible with all of the lights on, though slightly annoying since the glass surface reflects the lights overhead.


- implement basic single-value x and y offsets for multiple detectors

done and done. next up is line offsets -- offset x a certain amount based on y, then offset y by a certain amount based on the original x (not offset). shouldn't be too hard. need to select a data structure.


damn, i've already populated a giant post, and i haven't even come close to touching on what i wanted to write about in the first place. i think i'll double post for organization.

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