Pink Floyd's Next Album Cover?

Nope, this is the final blended and threshold-filtered image of all of the infrared images taken of the LiDAR footprint.  The grey line is a trendline I drew across through all of the footprint centroids.  The line runs from pixel 0,1800 to 3280,1000 and it hits all of the centroids about as well as I could have hoped. 

It's important to remember that the footprint centroid location on the camera CCD will vary along a line, but it will not vary linearly.  In other words, no matter how far MARCO is from its target, the footprint will be somewhere along that grey line, even if it's not in the field of view.  However the equation that describes exactly how far along that line the footprint will be depends on a mess of trigonometric functions that I worked out in a notebook on a plane 4 months ago and then forgot about until now.


At this point you may be thinking to yourself: "Jacob, you dumb idiot, if you can image the LiDAR footprint, why not just do that when it comes time to dock? What's the purpose of this whole calibration process?"

Well, MARCO can only see the LiDAR footprint through its IR filter, and the filter actuation process takes about a second to complete, which is about an eternity in the context of this project. I would also have to do some sort of noise-filtering programming (you can see the amount of signal-level IR noise in an environment that was about as noiseless as I could reasonably make it).  Furthermore, I would have to increase the exposure time of the camera to capture the footprint or I would miss it, adding more time to the process.

This method is faster, less computationally expensive, and more accurate when you consider that 11 overlaid footprint images can probably place the centroid more precisely than just one.

Comments

Post a Comment

Popular posts from this blog

The Future of MARCO

So I took some time, got a real job at NASA and I've been out traveling a bit, and I only just recently had some time to settle down and take a good look at this project from a more seasoned perspective.  For reference, when I set out to make this happen, I didn't know python, I had little experience with linux, and "computer vision" was little more than a buzzword to me.  I knew the math worked out, however I had a hard time translating the principles of MARCO from the realm of math where everything is clean and orderly to the real world where colors sometimes don't look like they should and the sun shines more brightly on some days than on others. I was not well-prepared to take on this project, and it's a good thing I started as early as I did because there's no way in hell I would have been able to achieve the fairly-positive results I got with less time. Be that as it may, I'm now in an incrementally better position to tackle this task, and I ...
Keep reading

Preliminary Results and higher-order error sources

Image
I have some test results today, and I'm quite happy with how they turned out.  Quick refresher of the parameters: range refers to the target distance in centimeters, a_ang is the rotation of the major axis of the projected ellipse, and b_ang is a measurement of the target's rotation about the major axis, both in radians. The convention when dealing with rotated ellipses is to measure the angle of rotation of the major axis from +j (beh) clockwise (BEH!) but also, since I went through the trouble of rotating these images so that they're not sideways, a_ang is measured clockwise from -i.  The elliptical fit is programmed to run along the inside edge of the larger target circle. {'range': 42.27010789888579, 'a_ang': -0.04591864992309163, 'b_ang': 0.3644755561635681} Standard up front shot, I'm impressed that the software picked up that the target is actually tilted upwards relative to the camera though I think .36 radians (20 ish degree...
Keep reading

A Working Filter Actuator

It may have taken a week and an unwieldy hardware solution, but I now have an operational filter actuator.  hooray The transistors I tried just simply could not supply enough current in series to the solenoid when biased by the 3.3V digital output of a GPIO pin, so I threw together a servo-operated switch that flicks the filters back and forth pretty reliably.  I've been testing the switch and actuator by setting the scripts that operate them on an infinite loop (see video) and after a couple of solder joint breaks and design revisions the assembly finally seems to be straightened out. In the meantime, I have continued working on the startup scripts. Of course I have scripts operating both lights and the actuator, and I am integrating them all into a sort of pre-mission check to verify functionality.  I have managed to take images using both the IR and visible light filters, and the pictures look good.  All that remains before the real hard part of this project i...
Keep reading