Creating a Polar Panorama1 Comment
This past weekend I was showing my work in the art sales tent on Grand Rapids’ Calder Plaza as part of the annual Festival of the Arts. It struck me that the urban plaza surrounded by tall buildings and filled with the trappings of the celebration would make a great location for a polar panorama. I asked permission to set up a tall ladder on the plaza at midday (to minimize shadows) and was told that would not be permitted–but they’d be happy to provide a boom lift for my use!
So at noon on the appointed day I road a boom lift up about 15 feet above the plaza at a point I had earlier selected for the composition I intended. I set up and carefully leveled my tripod and camera and took a series of overlapping photos as I rotated my camera in a full circle.
For the first shot I lined up my camera in the direction of the overhead sun and found an exposure of 1/200 second at f/11 retained detail in the bright sky. I set the camera on manual at these setting so that all of the images would have the same exposure. I was using a Canon EOS 17-35mm f/2.8 L lens set at 17 mm with the camera titled for vertical captures so that I could get the tallest nearby building completely in the frame.
Back in the studio, I opened the RAW files in Adobe Camera Raw. I selected all of the files in the filmstrip area on the left so that any adjustments I made would be applied equally to all the images. The exposure I chose kept detail in the highlights but was overall somewhat under exposed. So I increased the exposure and shadows sliders to lighten the overall image. (Click on the image to see full sized).
With the adjustment complete I selected the images in Adobe Bridge, went to the menu bar and selected Tools>Photoshop>Photomerge to create a standard 360 degree panorama. I found that the spherical layout option worked best and I selected all of the options below the source files list.
The resulting panorama was a bit more than 360 degrees so I carefully cropped it so that the edges would line up perfectly in the final image. The down side of using the boom lift was that the safety rail and base were included in the images, so I did some quick work with Photoshop’s clone, healing brush, and patch tools to edit them out. I knew I didn’t have to do a perfect job because the bottom of the panorama would be extremely distorted in the final image.
The rest of the process is fairly straight forward. First you resize the panorama to a square. In the image size dialogue you’ll have to check the “resample” box, click on the little chain icon that constrains the proportions, and then change the width to be the same as the height. The result is a very squished panorama.
Finally, you rotate the image 180 degree so it is upside down and then go the Photoshop menu bar and select Filter>Distort>Polar Coordinates. The resulting image had a faint vertical seam where the edges of the panorama met but a bit of quick work with the healing brush tool fixed that.