Camera orientation

The camera orientation consists of 3 independent parameters: 1) azimuth 2) elevation 3) rotation angle. The azimuth is essentially a measure of the where the camera is pointing relative to the cardinal directions: north, south, east, and west. The azimuth is measured with 0$^{\circ}$ azimuth corresponding to due north and progressing clockwise to the east at 90$^{\circ}$ azimuth and so on until arriving back at the north.

The elevation angle is a measure of how the camera is tilted in the vertical. A 0$^{\circ}$ elevation angle would correspond to a level orientation with the horizon near the center of the field of view. An elevation angle of 90$^{\circ}$ would correspond to the zenith, which is directly overhead.

Ideally, the camera should be mounted in such a way that the bottom is level with the ground. In this case, one only needs to know the camera azimuth and elevation. In actuality the camera is usually not perfectly level but is at least slightly rotated about the axis normal to the focal plane. Not correcting for this in the images can introduce significant errors, particularly near the periphery of the image.

Finally, the field of view of the camera must also be known. The field of view is measured in angular width units for both the X and Y directions. This only has to be determined once for a given lens or lens setting (for a zoomable lens).