Thursday, June 28, 2012

It's all About the Ratio

That's better!

Sorting out the aspect ration issue (should the width and height be determined by the difference of surfaces from inner our outer circle or be set by the radius & circumference), still needs some work.

But the next big challenge is to antialise the image.

Tuesday, June 26, 2012

1 != 1

And suddenly the problem comes in to focus!

It was not, as previously thought, a problem with the lens distortion or pixel shape. Or any other mythical unexplained reason. No, just a simple mix up with with the normalisation of the vectors.

If the image is not equal in height and width, then 1 X != 1 Y.

Monday, June 25, 2012

3D Glasses Needed

With the stand built, remote trigger working and synchronisation tested, it's time to take some 3D pictures!

Left eye - Righty eye

"Third" eye :P

The process works. Time for actual science!

With the lenses 24cm apart it's a bit to much perspective for humans (at least for the object in the front). But for a computer, who knows.

Camera Synchronisation

And now, the whole adventure that was porting the CHDK comes to this, taking synchronised images from multiple cameras at once. But it's still not that simple!

First we need some more hardware that will trigger the cameras:

Build after schematics on CHDK wiki, the voltage trigger works.

But now it needs to be tested with two cameras, to see if the image acquisition is synchronised, so we need one more piece of hardware:

A true scrap heap project composed of an unused electric motor from a model plane, some spare electronic elements, a CD holder from an ancient MacBook's CD drive and a brand new DVD which was drilled trough so a LED and a battery was mounted on it.

With this the synchronisation wheel came to be. By using the known exposure values on the camera and tracing the light trail made by the LED, the rotational speed was calculated to about 10.36Hz.

Now with this information the synchronisation between the cameras can be calculated:

Taking the same picture with both cameras at the same time with the trigger, the angles from the start and en of the light trail can be measured and compared.

So far, the exposure time was the same and worst calculated delay between the cameras was 0.3ms. Not bad, but this may still vary a bit, since so far it has only been tested with few pictures and on one set of settings.

Eye in the Sky

The prototype is ready for testing!

Want to take 3D pictures? Then you need a 3D camera. Or two cameras in this case (even got the right colors).
Want to fly with this contraption? They it has to be as light as possible!

Two carbon fibre tubes, length 100cm and diameter 10mm. Drilled trough a plastic box for electric components for orientation (it's good if they are parallel to each other) and bonded together with layers of super glue. The movable mounting for the camera is (for now) composed of an old xBee break out board with a hole for a 1/4'' camera mounting screw. All attached to the tubes with "snail" clamp.

Yes, the last part needs some work before it will be light enough to put on an rc plane, but for testing on the ground this works just fine.

Wednesday, June 6, 2012

Transit of Venus

Some more fun you can have with your hacked camera. Take a picture of a once in a life time event!

How to take a picture of Venus passing in front of the Sun. Simple, buy two pairs of sunglasses from the 1€/1$/(insert your version here) shop, to make a scrapheap version of shading and a polarising filter. Attach said creation to the camera:

After that, abuse the settings for the lowest possible ISO and exposure settings: