@dale said:
Thanks Roger for that detailed explanation. A question... to create a hemispherical global, is it a matter of lens, or do you have to rotate the camera on the z axis as well?
The answer is, it depends.
You can use a 180 degree fisheye lens and lay on your back looking up and get a hemisphere in one shot. Or you take the other extreme and shoot a hundreds of shots with an extreme telephoto (in the x,y and z axes and stitch them together).
The difference between the two is amount of work and resolution. The fish eye will be in the 5 to 10 megabyte range. The stitched image could be 40, 100 or even more gigabytes.
Mesa Arts Center
This is MAC (The Mesa Arts Center)in Mesa, Arizona. If I remember right this is composed of a matrix of 12 photos (4 across by 3 high). I guess the FOV might be 120 degrees. I had to do a fair amount of PS to get rid of the worst distortion. For comparison SketchUps dfault FOV is 35 degrees and I estimate our sharp field of view to be about 12 degrees.
As humans we stitch the images in front of us all the time, but we do it in our brain and in our memory. At 12 degrees we are really looking through a keyhole, but as the eye scans a scene it gathers many views and stitches them together. In fact this is also HDRI as I took a normal and underxposed view of ever position so I could keep the sails from over exposing. We are looking at two layers of 12 shots each.