How the Photos are Taken and Stitched
using the iPhone Panorama Head and PTgui
How many pictures do I need?
In the very least, you will need 12 images of 5 rows plus 1 shot each facing straight up and down for a total of 62 images. The iPhone 2G has a max image resolution of 1,600px by 1,200px yielding a final image of 11,000px by 5,500px.How do I take the photos?
The blessing and the curse of using an inferior camera for panorama photography is that while you do not have to worry about any settings, you hence have no control over the outcome. It may be worthy for you to install a camera app that allows for clicking a larger button or anywhere in the screen to take a picture. It may be useful when the iPhone is at angles where the screen is facing toward the ground. There are both free and paid apps that do this, some also claim to generate quality images at higher resolutions, that is they use sophisticated algorithms to digitally increase the dimensions of your images right before saving them into the iPhone’s memory.
I used a tripod. The Panamatic rotator has 12 stops which allows for a relatively small overlap among the horizontally spaced images. If you are using a different rotator, I recommend taking 14 or 16 images for each row. As you can see, 12 works fine though, if that’s all you can do.
I took the horizontal (tilt = 0 degrees) row of 12 images first. I then tilted the camera up 25-30 degrees and took another row. One more row above it and a zenith shot. I then tilted the camera 25-30 degrees below the horizontal, and repeated the above process facing the camera toward the ground. for the bottom shot, I stepped aside and held the iPhone as close as I could to the position it would have been if still attached to the head while facing straight down.REMEMBER
: As a rule of thumb, you would wanna have a 30% or more overlap between image pairs for best results.Bad News, Good News
The bad news is that the iPhone’s autoexposure will yield images light and dark. The good news is that today’s digital imaging tools will allow for massive leniency int hid category. PTgui, the stitching software I used to stitch the images even has its own exposure correction tools built right in. You can download my PTgui project file if you need it for reference from the files section
I brightened the images that seemed overly dark in comparison to the rest, then fed all of them to PTgui. There’s a spreadsheet like listing of all images in PTgui which allows you to type in he approximate location of each image. This process takes less them a minute, and significantly eases the software’s abilty to assemble the panorama. Having taken 12 images around, so we know that, horizontally, they are 30 degrees apart (0, 30, 60, 90 . . . 330). To provide sufficient overlap vertically, I tilted the iPhone approximately in 30 degree increments as I took each subsequent row of twelve images, for a total of five rows.
PTgui allows you to visually place the images for a rough alignment. If you do that for a single column (that is for one of the series of images fitting together from the same horizontal position of each row), PTgui will tell you what the tilt angle increments are for each, which - in turn - you can reuse for all images of the same row, knowing that our handy iPhone Panorama Head will keep those angles the same across a 360 degree rotation.Let The Stitcher Work/Fine tune
At this point, PTgui is ready to do the work for you, by automatically finding matching points (‘control points’) for you across every horizontal and vertical pair of images and will assemble the panorama for you. You can review your panorama without leaving PTgui and if you feel that the software failed to fit your images correctly, you can easily identify the relevant pairs and add your own control points (2 or 3 pairs for each at max) to assure perfect results.Blending and Making Things Pretty
PTgui also has a feature which allows you to have it correct the variation resulting from taking the images in autoexposure mode. You can ask it to do that for all or any number of the images comprising the panorama. In this case, I only felt the need to do this for the images of the sidewalk, but your mileage may vary.
The only thing you are left to do is using your favorite image editor to enhance colors/contrast and alike to your personal preference.