#PTGUI NADIR VIEWPOINT FULL#

If the panorama is being taken outside with no nearby objects of interest, these types of panos actually can be taken handheld. Like any panorama, it's best to try and keep exposure, white balance, and focus locked and consistent between member images, to consider whether HDR exposure coverage might be required with bracketing, and to shoot enough coverage/overlap so that you can erase ghosts and clones. But the goal is always the same: to completely cover the sphere with enough overlap for a good stitch. There are variants to this type of coverage, of course, mostly altering the angle of tilt to eliminate the need to shoot a separate zenith or nadir or both. The most common technique used for shooting these panoramas is to use a fisheye lens, to hold the camera in portrait orientation (for the most vertical coverage), and to shoot a row of images, while rotating the camera/lens as closely as possible around its no-parallax point (NPP), and then, if required, to rotate the camera in pitch around the NPP to take zenith (straight up) and nadir (straight down) shots to finish coverage.

If you need something quick and dirty and this isn't about requiring a super-high-resolution seamless end result, these can be fun and much simpler ways to create VR panos. In the wake of Facebook and Youtube supporting 360º video, there are now a number of 360º action cameras that do more or less the same thing with the same strengths and weaknesses. But there's very little overlap, so more of the edges (which fisheyes are traditionally weakest) are used in the final stitch. It can even do 360x180 videos, and is more convenient than the fisheye-and-stitch process. Ricoh came out with a neater solution, the Theta, which essentially pairs two fisheye lenses back-to-back to cover the sphere, and internally stitches the two images together.

#PTGUI NADIR VIEWPOINT FULL#

There are also 360 'one shot' type mirrors to capture the full 360 without having to stitch, but the vertical field of view won't cover your floor and sky, and again, the quality of the image is going to rely heavily upon the quality of the mirror, and again, the results won't be as good as shooting individual images an stitching. This technique is often used to create HDR environment maps for cgi work, but the quality of the image depends highly on the quality of the ball bearing, and typically the results won't be as suitable for VR photography. You can actually make a 360x180 panorama with two shots and a regular camera by shooting a large chrome ball bearing. Sidenote: Lightprobes, One-Shots, and 360º cameras

A rectilinear lens will get you higher quality, higher resolution images, but require a lot more work. Which is why most people who shoot these use fisheye lenses, to reduce the amount of shooting and stitching required. But if, say, you were to use the Canon EF-S 10-22 on a crop body, at 10mm, in portrait mode, assuming 25% overlap (which actually isn't that good) you'd need 7 images to cover 360 degrees in yaw, and probably 3 rows and a zenith (straight up) and nadir (straight down) to cover the full view. There are field-of-view calculators out there that can tell you how many shots you'll need with any given lens. Rectilinear lenses simply don't have the scene coverage required to stitch together a full sphere/cube in those few shots. However, if you want to take a 360x180 in six shots or less, you're going to have to use a fisheye lens. You end up with 2x1 rectangle that has a huge amount of distortion at the poles, but which does represent the entire sphere. The latitude and longitude on the sphere is simply mapped to Cartesian y and x coordinates, respectively. The equirectangular mapping is the most convenient because it can encompass the entire panorama in a single image. VR panos are typically represented in one of two formats (although there are others): six cube faces, and equirectangulars. Cartographers have worked out a lot of these over the centuries trying to map the earth in representative ways. There are a lot of ways mathematically to represent a sphere. Those 'six shots' you're seeing are typically remapped cube faces from a full panorama. The basic process is to shoot enough images to cover the entire sphere, and then stitch them together as a panorama.

A good overview of the techniques for shooting this type of 360x180/equirectangular/VR panorama can be found on Eric Rougier's fromparis website.

Ptgui nadir viewpoint