Showing posts from 2012

GoPro Hero3 Black Multi-Camera Timing

In the previous post, I explored the field-of-view of a GoPro Hero3 Black camera.  In this post, I explore the timing of two cameras, both paired with the same remote.  I set the cameras to 848x480 240Hz video, pointed them at a kitchen timer that has an LED blink once per second, and recorded.  Here are four images from each camera, composed together so you can see how the timing varies:

So, accurate to within 2 frames at 240 Hz - only about 8 milliseconds or so of difference.  Should be good enough for my purposes.  The bigger concern is the color shift apparent between them.  Note that the bottom image seems a little more saturated than the top.  Probably correctable, but annoying.

GoPro Hero3 Black Field of View

I got two GoPro Hero3 Black cameras and am planning a panoramic project with them.  However, to do the project correctly and accurately, I need a good read on their field-of-view.  So, I set up a tripod and a grid and a tape measure, and took a few photos.  Here they are, desaturated and contrast-enhanced, with central red dots and some annotations.  First, measuring the diagonal FOV:

Next, the horizontal FOV:

Finally, the vertical FOV:

The front of the camera lens was almost exactly 17 inches from the grid.  The camera body started about 17.25 inches from the grid.  Assuming the sensor is embedded some distance into the body, I used an estimated field-to-sensor distance of 17.5 inches.  This yields the following field-of-view, in degrees:

Diagonal: 146
Horizontal: 121
Vertical: 93

Doing a little interval math on the field-to-sensor distance shows these angles are accurate to about plus or minus 1.5 degrees.

Interestingly, Photoshop seems unable to correct the barrel distortion of th…

Apollo Inception

I found out this weekend (Aug 25/26) that everything goes better with Inception. So, in honor of Neil Armstrong's passing, I made this montage of Apollo 11 footage from NASA footage ( ) and the music Mind Heist by Zack Hemsey ( ) The only concession to timing was that I cut a few seconds of Walter Cronkeit's face out to match the length.

Everything *does* go better with Inception!

Neil Armstrong, 1930-2012

July 20, 1969.  I was 5, and my father had just returned from Vietnam.  He took me outside that night to see the Moon.  It was not quite this full - 6 days instead of 8 as pictured here - but still stunning.  A person was walking on the moon!  The Apollo program had a huge impact on my childhood, and strongly influenced my choice of engineering as a career.
There will be plenty of tributes to Neil Armstrong today, but for me, it is enough to say that a giant of American history has passed.
I took this photo this evening in memory of Neil.  May we honor his memory by continuing to explore the Universe.

Venus Transit Images

As documented in my Expedition Notes, I was on the summit of Haleakala for the 2012 Transit of Venus.  Here are a couple of representative images.  First, the beginning of the transit, in white light - a stack of 10 images taken with a Canon EOS 40D and aligned and processed in Photoshop.  Click on the image to see it full-size:

This is the color of light the Sun puts out.  It is not yellow or orange - people only think it is because the only time you can actually stand to see the Sun is when it is rising or setting, especially through clouds (and it is still not safe to look at it this way!).  At those times, the light is significantly reddened from the passage through very thick layers of air and dust.  Note the sunspots and other details - white light is interesting.  But what is *very* interesting is Hydrogen Alpha light.  This image of the end of the Transit is a stack of 7 images taken with a Sony NEX 5N camera and aligned and processed in Photoshop.  Again, click on the image …

Venus Transit Expedition 2012

This year, we planned a family outing to Hawaii.  Being a science geek, I said, "If we are going to Hawaii this summer, let's make sure we are there on June 5 for the Transit of Venus".  Hawaii is one of only a couple of spots in the United States where the entire transit would be visible.  And so, we chose early June for our vacation.  Our target was Maui; specifically, the summit of Haleakala, the highest peak on Maui:

View Larger Map

We chose Haleakala for several reasons.  First, Maui is indeed a tropical paradise, an excellent spot for a family vacation.  Second, at 10,023 feet, Haleakala is almost always above the clouds.  Finally, we anticipated that the world + dog would descend upon (ascend up to?) Mauna Kea on the Big Island, making it very difficult to find a good spot to set up telescopes - in fact, we heard later that only shuttle buses were allowed to the summit, so we were quite likely the highest-altitude amateur observers of the transit on Hawaii!  Possi…

Partial Solar Eclipse

Today, much of the western United States got to see a partial solar eclipse.  For some lucky observers, they got to see an annular eclipse (where the silhouette of the moon was completely centered in the sun).  Here in Fort Collins, it was "only" partial - but pretty spectacularly partial (up to 85% obscured).  Unfortunately for me, the clouds completely eclipsed the maximum eclipse.  However, I got a nice sequence of the rest of it up until sunset.  This is a composite of images taken roughly every 5 minutes during the eclipse.

Edit - here is an edited version to bring out the contrast a little better.  Note the limb-darkening of the Sun versus the very sharp edge of the Moon.

The sharp-eyed might note that there is a stray "sun spot" on one of the images.  It is a bird who flew through during the exposure...

Notes - this series was taken with a Canon EOS 5D Mk II camera - most exposures were 1/1000 sec at ISO 400.  The camera was attached to a 1000 mm f/10 Schmid…

Doing what matters

When I was about 11 or 12, I had a rock collection.  A few dozen fossils and geological oddities that I had picked up here and there.  They all fit in a single glass case – I could see them all at once, and instantly knew the significance of every rock.  However, I was also a frequent visitor to natural history museums.  I noticed, in those museums, that the professional geologists and paleontologists had a catalog system that helped them keep things straight, and also see patterns which generated deeper insights.  With this catalog system came labels on the samples.
So, one day, I typed up (on a manual typewriter!) a few dozen labels for my own personal catalog system.  As I recall, each label contained the date I collected each sample, its original location, and a sequence number.  I carefully glued these labels to each of my specimens, and then stepped back to admire my creation.  Look what I had!  It was a… a… a… a rock collection.  With labels stuck to it.  It was not a museum, or…