Stripey Panorama

Previously, I wrote about how to make a 360° panoramic time-lapse film using an egg timer. For the photo above, I didn't want to go with twelve 30° views, but instead combine all 360 images into one panorama. This meant to cut from every photo a tiny narrow centre slice (only 22 pixel wide in fact), which is equivalent to one degree field-of-view. These were then all combined into one large image. If you look carefully, you can make out the stripes.

On the next day, the weather was much nicer, and I repeated the egg-timer photography. However, due to the GoPro camera's fully automagic exposure settings, and the high variability in lighting caused by fast moving clouds and the bright Sun, it was not possible to make a nice pan-lapse out of these photos, and as you can see, the stripiness is much more pronounced in this image, even though the blue sky is very nice of course.

By the way, the strange black boxes in these photos are part of the Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA). The mountain directly under the Sun in the second photo is famous Saana.

In due time I will write about how these were done in detail, in case you want to try yourself.

You can click on the above images to get larger versions.

Original photos and panoramas: Thomas Ulich.

Another article about this you can find on the KAIRA blog.

Pan-Lapse Film

In late June, I went to Kilpisjärvi on a service mission to Finland's largest radio telescope, the Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA), which was built there by our institute, the Sodankylä Geophysical Observatory. The first thing I did upon arrival, was to place a GoPro time-lapse camera on an egg timer, in order to make a full 360° panoramic time-lapse film (YouTube).

Do you want to know how I did it? Then read on...

The GoPro cameras (Hero 2 above) have excellent optics for what they are, since they have a fixed focal length (no zoom) and also have fixed focus. Thus the extreme wide-angle lens needs to do only one thing and is optimised for that. Also, the GoPros have a built in time-lapse mode, i.e. they can take 11MP or 5MP images at a number of set intervals between half a second and one minute.

The cheapest way to make rotating time-lapse films is to mount the camera on a cheap (about 4€ or so) IKEA egg timer. The timers do a full 360° rotation in one hour, which is a good duration for a time-lapse. The only negative point is that they can only rotate in one direction (unless turned upside down).

For the film above, I programmed the camera to take a photo every 10 seconds, and set the timer to 60 minutes. Thus the camera was set to take one image per one degree of rotation. Rather arbitrarily, I decided then to use these images to stitch them together to 360° panoramas by using twelve 30° sections. These sections are indicated by the grey lines in the image at the top. Thus I needed to take every 30th image and see how much they overlap, and cut away the overlapping parts in order to have only the 30° centre sections. Then I stitched the 12 images together, 30 images apart, leading to a 360° view.

Now, since the camera took a photo for every degree of rotation, I made 360 different panoramas, each shifted by one degree with respected to the previous. These were then combined into a full panoramic time-lapse film, also called a pan-lapse film.

If you look carefully when watching the film (e.g. look at the clouds), you will see that the same bit of film repeats in every pane and migrates from left to right through all panes. In other words, every pane is a 30-image time-lapse film, repeated through all twelve panes, and thereby making up a film of 360 frames. The film looks really nice when put on loop, but this is unfortunately not possible on YouTube.

There are a few other games one can play with this set of images, so watch this space!

By the way, I got the idea of pan-lapse films from Ken Murphy of Murphlab, please visit his site for this and other exciting time-lapse projects.

Photos and time-lapse film: Thomas Ulich.

Another blog post was published about this on the KAIRA blog today.