Date of Award


Degree Name

Master of Science


Computer Science


Steven Roach


Cassini entered Saturn's orbit on July 1, 2004 beginning a

four-year exploration of Saturn. In 2008 the mission was extended,

and Cassini continues to collect and transmit images and data

collected during its mission. In order to accurately interpret

images, it is necessary to know the location and orientation of

the camera provided the field of view when the image was

collected. While the mission managers provide initial estimates of

this orientation, scientific analysis requires better estimates

than the initial data provided. Navigation is a process for

improving the estimation of the true camera pointing vector as

determined by features identified in an image. Features such as

the body of Saturn or specific rings can be utilized to

approximate the correct position and orientation of Cassini.

The Cassini Viewing Utility (CASVU) is a set of tools developed by

the Software Engineering Research Group at the University of Texas

at El Paso designed to facilitate the analysis of data returned by

Cassini. In particular, the \emph{Navigation} tool is provided

for the correction of orientation and positioning of Cassini.

CASVU uses the perspective projection approach to model a 3-D

environment as seen from Cassini. The 3-D model is composed of

wireframes that provide a predict view of Saturn and the rings

assuming the initial estimation of camera orientation. These

wireframes are superimposed on an image collected by Cassini.

Features in the images are identified, and a Fast Fourier

Transform based algorithm computes rotation and shift ratios

between the predict wireframe and image. These ratios can then be

applied to the predict wireframe to correct the pointing vector of


This Thesis presents a semi-automated FFT-based navigation

algorithm that can be utilized for the correction of spacecraft

pointing estimates when integrated into CASVU.




Received from ProQuest

File Size

69 pages

File Format


Rights Holder

Francisco Javier Osuna