Friday, June 5, 2009

The End?

Over the past week I've begun to scratch the surface of how computer vision works. I vaguely understand how homographies work, and have now written code that effectively calculates the homography for us - of course, using OpenCV for the heavy lifting. The image above is a digital snapshot of our projection layout, with GIMP doing a Sobel edge detection routine. It does an amazingly good job of determining the outlines for me. I then pull the overall outline I want, the real corners of the whole projection, and the real corners of each individual projection together into a format and feed it through a couple of FindHomography() calls and some matrix math - some of which I understand, other bits I still find fuzzy. This has ultimately worked out to make a pretty good set of homographies for our distortion.

My code outputs some nice matricies, with the Z axis being the identity matrix, such as the following format:

0.999593 0.005707 0.000000 0.000021
0.006457 0.889109 0.000000 0.000035
0.000000 0.000000 1.000000 0.000000
5.278528 4.951293 0.000000 1.000413

0.931133 -0.005690 0.000000 -0.000004
-0.008387 0.845363 0.000000 -0.000004
0.000000 0.000000 1.000000 0.000000
98.365417 20.241795 0.000000 1.000408

0.832297 -0.006445 0.000000 -0.000033
-0.033426 0.804530 0.000000 -0.000009
0.000000 0.000000 1.000000 0.000000
191.126740 16.284946 0.000000 0.993720

0.915757 0.025370 0.000000 0.000020
-0.030621 0.760372 0.000000 -0.000041
0.000000 0.000000 1.000000 0.000000
75.373116 217.128815 0.000000 0.995069

0.945395 0.024405 0.000000 0.000015
-0.043237 0.795157 0.000000 -0.000028
0.000000 0.000000 1.000000 0.000000
102.483498 181.870300 0.000000 0.999334

0.971726 0.028967 0.000000 0.000015
-0.094872 0.790870 0.000000 -0.000042
0.000000 0.000000 1.000000 0.000000
97.195442 129.874069 0.000000 0.997895

Each 4x4 matrix corresponds to our perspective correction factor, at least so we hope. In practice this is good, but not perfect.

Now that the end is here, part of me doesn't feel like letting this project go. I wasn't really expecting to feel this way, the way stress was heaped on - but right at the end, the hooks finally got me. I wasn't doing a mechanical design anymore - I was doing what I know and enjoy, math and software. So it goes though.

Wednesday, June 3, 2009


As delayed as this might be, it would appear the mechanical nature of the project is near completion. Mirrors are mounted, tilting is possible though unable to be stuck. The overall weight of the the tilt is a force to be reckoned with, unfortunately. With any luck though, our tilt mechanism should be here today for final work. This would be an exciting and important milestone for me. While everything has not turned out in a way that I would wish, it has turned out in a way that is acceptable for proof of concept, which is effectively what this is.

Friday, April 3, 2009

Wood's working.

I've been working on this table for about a week now, and while it's by no means a perfect piece of woodworking, it is sturdy, stable, and at least somewhat attractive. It's not precisely what we had in mind originally, but it's a functional table and should be an effective touch platform. My concerns are more regarding the 60 degree tilt version, which may have to be much taller to support the depth necessary to rotate comfortably, or another design may need to be thought up. This isn't an easy thing, particularly considering the potential weight. Part of me is reverting back to some of the original ideas a bit more than the drafting table. These are cleaner, more elegant solutions to what we're trying to accomplish.

The drafting table, I'm afraid might be too tall. Then again, drafting stools are typically quite tall. Perhaps a lifting 'top'? But this has the issue of moving the equipment properly as well. Maybe there can be a connection between top and bottom so that when one lifts, they both lift in unison. This, is an interesting idea.

Monday, March 23, 2009

As of late this afternoon, the last quarter was finished.
What does this mean? I only have this to focus on. It's go time.

Tuesday, March 17, 2009


The presentation seemed to be fairly successful tonight.
Overall I was very impressed by the quality of the presentations. While by no means was anyone a motivational speaker that commanded attention, they were generally well thought out and effective. Some stronger than others, but I enjoyed the entire experience.

Monday, March 16, 2009

This idea has been bouncing around my head a bit lately, but here's an actually implementation:

Thursday, March 5, 2009


AMS 147 Final: Next Thursday (5-10 hours study time)
AMS 147 Project: Next Next Thursday (10-15 hours)
AMS 147 HW 7: Last Friday (2-3 hours)
AMS 147 HW 8: Tomorrow (2-3 hours)
EE 157 Project: Next Next Thursday (10-15 hours)
EE 157 Final: Next Next Thursday (Petersen take home. Ergh.) (10-15 hours)
CE 123A Presentation: Next Next Monday (5-10 hours)
CE 123A Final Report: ? Next Next Monday? (~4-5 hours)
CE 123A Block Diagram: Next Next Thursday? (2 hours left?)
CE 123A Team Charter: Next Next Thursday? (2 hours left?)
CE 123A Project Proposal: Next Next Thursday? (2 hours left?)
TBP District Conference: Tomorrow and Saturday. (5+ hours tomorrow, 7-8 hours Saturday.)

At least we have the team for the 123A items. Time to study.

Monday, March 2, 2009

The beginning.

So, at the very moment activity inside my head is running on high. There's quite a bit to do still before I can really focus on what is going to go on here. This weekend is going to be crazy, and I may need some time for myself soon. Little bits and pieces are coming together, not necessarily at the speed I'd like, but at a speed that's expected even from five busy people. Next quarter I think things will improve, particularly if we can view this as our job and potentially our livelihoods.

There are quite a few design choices to be made still too, particularly regarding documentation. The whole blog concept as an academic journal though, I think is really spot-on. I can't keep equations here comfortably, but I'll keep my pen-and-paper variety notes for that. If they're important enough they can make it up here.

Anyway, just some initial thoughts.