Choose either Horizontal or Vertical. Also, if you are using a cross image (rather than six discrete images), use the following option. This (and the following option) are designed for use with cross images generated by HDR software.
Browse to the location of the cross image that you want used for a cube environment texture.
The image files mapped to the right, left, top, bottom, front, and back inner surfaces of an infinite cube. (The front of the cube faces the front orthographic window.)
