Extracting Rectilinear Images from Panoramas
Helmut Dersch

Panoramic images employing cylindrical projection can be generated in a variety of ways:

Often, perspectively corrected rectilinear partial views of these panoramas are wanted. This article describes how these can be extracted using free software (Panorama Tools). Image extraction uses high quality interpolators preserving the quality of the original photograph and making them suitable for printing.

An Example

The following image is a 360° panorama generated using the Roundshot camera equipped with a 14mm lens.  (original photograph by  Julio Moya, j_moya@idecnet.com)


To extract partial views, select a viewing direction by choosing proper yaw and pitch angles, in this case we use yaw=-115° and pitch=0°:

Then decide which field of view you wish to show: 50° corresponds to normal vision, whereas 104° is rather wide. Finally, you have to choose pixel dimensions for the extracted image, ie width=500 and height=300.

Now open the panoramic image in Photoshop, choose 'Panorama Tools' and 'adjust'. Push 'Prefs' and select options (b) and (c). Then, back in 'adjust', select 'extract' and 'use options', push 'set' and fill the dialog as shown below:


Clicking 'OK' twice initiates the transformation and results in the upper left image below. The other images were extracted using different yaw angles, and the last image corresponds to a camera tilted down by a pitch angle of -45°.

Notice that the lower left image runs across the seam from left to right, and some retouching may be required before printing. Finally, other image dimensions and fields of view are equally possible as shown by the "portrait"-images below:

Some Additional Comments:


1999 © Helmut Dersch  der@fh-furtwangen.de