Part 2: PTGui and the Control Point Assistant

You have your first images on your hard disk?

OK  - to give us plenty of work to do I have chosen a real and "imperfect" set of images.  They were taken handheld and do not meet the nodal point!

If you want to, you can also use my source images (reduced quality, 3.4 MB download)

fisheye1.jpg (4873 Byte) fisheye2.jpg (4872 Byte) fisheye3.jpg (4774 Byte) fisheye4.jpg (4832 Byte) fisheye5.jpg (6172 Byte)

Fisheye lenses tend to have very recognizable light falloff on the outer parts of the image. Also chromatic aberrations are a big issue. You may want to minimize these flaws before stitching your panorama.
Here are some good resources how this can be done:
PTShift by Eric Gerds
More technical background about chromatic aberration can be found at the homepages of Jim Watters and Erik Krause.

The images show the recently renovated "Kloster- und Wallfahrtskirche der Unbeschuhten Karmeliten" in Vienna.

The first 4 images are taken in portrait mode. The 5th image is the so called zenith- or sky-image. I did not shoot a nadir- (or floor-)image because of the regular texture of the floor.

To capture the high dynamic range of the interior i have slightly under-exposed. To get the correct exposure, we have to adapt the brightness of the finished panorama.

Please start now by opening PTGui and loading the Source-images:

For further processing the images, we need to rotate them to portrait mode. A simple method is to use the "PTGui Project Assistant" on the first tab.
If you get a popup window when loading the source images, telling you about EXIF-data in the JPEG-images, you can savely omit this dialog by pressing [Cancel]. This is, because PTGui can't automatically detect Fisheye images.
Rotoate the images accordingly and enter the correct values of your lens in the fields below. Some examples of widely used lenses:

  • 8mm Fisheye (e.g.. Sigma): Lens type: Circular, H-FOV: 160. - This is the horizontal FOV, therefore it is only 160 on a typical DSLR. Full frame cameras or Film Cameras will use the full 180 degrees.
  • 10.5mm Nikkor DX Fisheye: Lens type: Fullframe, H-FOV: 130.

Now click the [Generate Control Points] button. After some time, PTGui will have generated some Control Points and pre-optimized the panorama. Don't be confused by the strange appearance of the optimization. We will correct this now step by step:

First of all - check if PTGui has correctly set up a full equirectangular Panorama:

Because the Assistant has mis-interpreted the rotation, we will roughly correct rotation. This can be done with the PTGui Editor:

The correct re-calculation of the source images will take place when releasing the mouse button.

Also, Don't worry about the black edges of your source images. You can remove them by clicking on the "Crop"-tab. Cropping the image is helpful for visualizing the panorama in the editor window and a smoother overlap between the images.

With a click on the button "Apply to all images" we will transfer the crop to the rest of the images.
If you look closely you will notice that PTGui automatically adapts the field of view of your lens. This is OK - we use a guessed value which normally would be about 170-180 degrees of a 8mm fisheye on a DSLR.

Now advance to Part 3: Fine-tuning with PTGui