Yesterday, my friend Sophie Nuber and I hiked to the top of a hill overlooking San Luis Obispo Bay, near my home. The climb was tough for me because: 1) I am old, and 2) I was carrying the tripod, the GigaPan unit, a large cheese sandwich, 2 liters of water and my Canon camera – a total of about 40 lbs. of gear. This gear was recently lightened by my discovery (duh!) that I didn’t need the fluid head on the tripod when making GigaPan images. So I removed the fluid head (about six pounds) and replaced it with a simple 75mm ball socket base on the GigaPan itself. I’m surprised it took me so long to figure that out.
At the top of the hill I set up for the photo only to discover that I had failed to bring the dumb little tripod adapter that attaches the lens to the GigaPan bracket. I wasn’t about to go back down to get it; that would have taken an hour, and I didn’t have the energy to do it again. Sophie suggested that I use the strap from the backpack to hold the camera to the mount. That turned out to be a great idea, and soon the problem was solved. The Canon and its 100-400mm lens were solidly (?) attached to the bracket and I started the panoramic image with the GigaPan device.
The red strap is from my backpack. I used it to hold the camera to the mount, just a little bit crooked.
This particular photo is going to be nice because it includes more than 180 degrees of the vista from the hilltop, called Sycamore Ridge, and three piers that go out into the bay. A couple of days earlier I might have captured a couple of humpback whales that were visiting, but yesterday there was no evidence of them.
There is an additional pier that will be visible in the finished panoramic image, that one being the pier at Pismo Beach, which is in the photo in the slightly hazy distance. Also visible in the photo is the beautiful Pismo Beach sand dune area, a huge stretch of white sand that goes from the city of Pismo Beach for several miles all the way into Santa Barbara County to Point Sal, just north of Vandenberg Air Force Base.
The GigaPan calculated that I needed 858 photos – 66 columns of 13 rows of images. It took about an hour to make the necessary shots.
What I failed to notice was that the camera and lens were slightly off-keel on the horizon, about 2.4 degrees off, a result of my strapping the camera to the mount a little bit awry. This meant that I took all 858 photos a tiny bit off-axis.
Of course this was obvious in the images as I transferred them from the memory cards to the computer, but I assumed that the GigaPan Stitch software could correct for this. PTGUI, the other stitching program I use, can correct for horizontal axis errors. Hours later, when the GigaPan Stitch software was finished, it was obvious that it cannot correct for that much horizon error. My piers were chopped-up into zig-zag lines, the hilltops in the distance were inconsistent and broken. My GigaPan was a no-go. A disaster.
My options were to fix it using software or to hike back up there and do it again. This, of course, would require another cheese sandwich.
So instead of heading over to the deli, I decided to try it with software. I made an Action in Photoshop, one which straightens the horizon of a photo by the necessary 2.4 degrees (as measured with Photoshop’s Ruler tool). (In Photoshop CS6 there is a also minor change to the Straighten command that I will discuss in a future blog.)
This is one of the 858 crooked photos. You can just see Photoshop’s Ruler tool ending on the right edge. To use that tool, you draw a line where you want the horizon to be, then click on the Straighten button at the top. This image shows some of the beautiful sand dunes south of Pismo Beach, California.
The straightened image has a perfectly level horizon, and still has enough overlap with the adjacent images to make a panoramic image in GigaPan Stitch. I recorded this horizon correction as an Action in Adobe Photoshop, then applied it with the Image Processor, which converted the images from Camera Raw to TIFF at the same time.
Once this Action was built and saved, I tested it on a few images to ensure that it worked correctly, and then I instructed the Image Processor to straighten the horizons of all 858 images from yesterday’s hilltop photo. GigaPan Stitch requires photos to be in either TIFF or JPEG for processing, so I had the Image Processor make that conversion (from Camera Raw) at the same time. It took over an hour to run all 858 images through the process, but it worked fine, resulting in those images being straight, and in TIFF format, ready for the GigaPan stitching program.
That program is running now on the newly-processed images, and it takes a long time. I will post an example of that image once it’s complete.