| 84 |
|
to the letter 'c'. |
| 85 |
|
This view is like a standard perspective vertically, but projected |
| 86 |
|
on a cylinder horizontally (like a soupcan's-eye view). |
| 87 |
< |
Two fisheye views are provided as well; 'h' yields a hemispherical fisheye |
| 88 |
< |
view and 'a' results in angular fisheye distortion. |
| 87 |
> |
Three fisheye views are provided as well; 'h' yields a hemispherical fisheye |
| 88 |
> |
view, 'a' results in angular fisheye distortion, and 's' |
| 89 |
> |
results in a planisphere (stereographic) projection. |
| 90 |
|
A hemispherical fisheye is a projection of the hemisphere onto a circle. |
| 91 |
|
The maximum view angle for this type is 180 degrees. |
| 92 |
|
An angular fisheye view is defined such that distance from the center of |
| 93 |
|
the image is proportional to the angle from the central view direction. |
| 94 |
|
An angular fisheye can display a full 360 degrees. |
| 95 |
+ |
A planisphere fisheye view maintains angular relationships between lines, |
| 96 |
+ |
and is commonly used for sun path analysis. |
| 97 |
+ |
This is more commonly known as a |
| 98 |
+ |
"stereographic projection," but we avoid the term here so as not to |
| 99 |
+ |
confuse it with a stereoscopic pair. |
| 100 |
+ |
A planisphere fisheye can display up to (but not including) 360 degrees, |
| 101 |
+ |
although distortion becomes extreme as this limit is approached. |
| 102 |
|
Note that there is no space between the view type |
| 103 |
|
option and its single letter argument. |
| 104 |
|
.TP |
