A virtual tour is a simulation of an existing location, usually composed of a sequence of videos or still images. It may also use other multimedia elements such as sound effects, music, narration, and text. It is distinguished from the use of live television to affect tele-tourism.
The phrase “virtual tour” is often used to describe a variety of videos and photographic-based media. Panorama indicates an unbroken view, since a panorama can be either a series of photographs or panning video footage. However, the phrases “panoramic tour” and “virtual tour” have mostly been associated with virtual tours created using still cameras. Such virtual tours are made up of a number of shots taken from a single vantage point. The camera and lens are rotated around what is referred to as a no parallax point (the exact point at the back of the lens where the light converges).
A video tour is a full motion video of a location. Unlike the virtual tour’s static wrap-around feel, a video tour is a linear walk-through of a location. Using a video camera, the location is filmed at a walking pace while moving continuously from one point to another throughout the subject location.
1.) Rectilinear stitching. This involves the rotation of a digital camera, typically in the portrait (up and down) position and centered directly over the tripod. As the operator manually rotates the camera clockwise, the camera stops or clicks into a detent at regular intervals, such as every 30° of rotation. The rotator can be adjusted by changing the position of “detent ring or bolt,” into another slot, to alter the interval of rotation: 40°, 60°, 90° etc.
If a given camera lens supports a wider view, one could select a larger detent value (for example, 60° instead of 30°). With a larger detent interval, fewer images are needed to capture a complete panoramic scene. The photographer may only need to take 6 shots as opposed to 10 shots to capture the same panorama. The combination of a precision rotator and a digital camera allows the photographer to take rectangular “slices” of any scene (indoors or outdoors). With a typical point and shoot digital camera, the photographer will snap 8, 10, 12 or 14 slices of a scene. Using specialized “photo stitching” software, the operator then assembles the “slices” into a single rectangular image, typically 4,500 pixels to 6,000 pixels wide. This technique, while extremely time consuming, has remained popular even through today as the required equipment, rotator heads and software are relatively inexpensive and easy to learn. A stitched panoramic view is also called “cylindrical”—as the resulting stitched panorama allows panning in a complete 360°, but offers a limited vertical field of about 50° degrees above or below the horizon line.
2.) Spherical stitching. This method requires the use of a “Fisheye lens” lens equipped digital SLR camera. The 2-shot fish eye camera system was made popular by IPiX in the mid-1990s and a two-shot rotator head that rotated and locked into 0° and 180° positions only. The camera was an Olympus or Nikon CoolPix camera and the lenses used were the Nikon FC-E8 or FC-E9 fish-eye lens. The IPiX 360 camera system enabled photographers to capture a full 360 X 360 floor to ceiling view of any scene with just 4 shots as opposed to the more time consuming 8, 10, or 12-shot rectilinear produced panoramas described above. This type of virtual tour required more expensive virtual tour camera equipment including (for example) a Sigma 8mm f/3.5 lens which allowed photographers to set their rotator heads to 90° and capture a complete virtual tour of any scene in just 4 shots (0°, 90°, 180°, 270°).
3.) Cubical stitching. This technique was one of the first forms of immersive, floor to ceiling virtual tours. Apple Computer pioneered this with the release of Apple’s QuickTime VR in the early 1990s. Free utility software such as Cubic Converter and others allowed photographers to stitch and convert their panoramas into a “cube” like box to achieve a complete 360 X 360 view. Today, this technique is considered rather “old school,” and spherical stitching has become more mainstream for producing these types of tours.
4) One-shot optics: Using one-shot panoramic optics one can create quick and easy panoramic videos and images such as the type used on the iPhone.
While programs such as Adobe Photoshop have new features that allow users to stitch images together, they only support “rectilinear” types of stitching. Photoshop cannot produce them as quickly or accurately as stitching software programs can such as Autodesk Stitcher. This is because there is sophisticated math and camera-lens profiles that are needed to create the desired panorama image which is based on your camera’s depth of field (FOV) and the type of lens used. Cameras such as the Nikon D3 or D700 have a full frame digital SLR cameras, whereas the Nikon D90 or Canon T2i (Rebel line of Digital EOS cameras) have a smaller sensor. When full frame digital SLR cameras are used with a fish eye lens such as a Sigma 8mm F/3.5, a full circular image is captured. This allows you to shoot 2 or 3 shots per view to create a 360 X 360 stitched panoramic image. When used with a non full frame digital SLR camera like the Nikon D90 or Canon digital Rebel and similar cameras, 4-shots are required with the camera in the portrait position. The resulting image will have the left and right sides cropped off each of the 4 images and each of the four corners, creating a rounded image.