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QTVR Panoramas - Implications
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Choice of Lens and the Size of the Panoramic Image
You now know that QTVR panoramas are based on a cylindrical view of 3D space. This fact implies that the choice of lens used to capture source images has a direct impact on the size and shape of the final panoramic Pict. This may not seem evident at first, but it's a great practical application of that geometry you studied in high school.
By using a lens with a greater vertical field of view, the size of the panoramic cylinder will actually decrease. This is due to the fact that the vertical height of the cylinder is the same regardless of the lens used. To verify this, let's compare two lenses: a wide angle 15mm lens, and a less wide angle 28mm lens.
Assume the source images from both the 15mm and 28mm lenses are captured with a camera in a portrait orientation and that the final panoramic Pict is created from images at the mid-sized PhotoCD resolution (768 x 512 pixels). Thus, the panoramic cylinders produced by each lens will both be 768 pixels tall:
15mm lens cylinder |
28mm lens cylinder |
Since the vertical field of view is greater for the 15mm lens, it will have a shorter radius for the cylinder.
Radius of 15mm lens |
Radius of 28mm lens |
You can see that the distance around the panoramic cylinder for the 15mm lens will be shorter than that for the 28mm lens. The choice of lens thus has a direct relationship not only to the vertical field of view of the final panorama, but also to the size (i.e., the circumference, or distance around) of the panoramic Pict itself. Wider angle lenses result in smaller panoramic Picts.
| This is an important implication for web-based authors who need to keep file sizes small. |
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