Looking at the documentation page it appears you're trying to use the "Define UAV Platform and Mount Sensor" section of the example as a model for your code. The first line of that section loads data from a MAT-file. I believe the scene, position, and orientation variables are stored in that MAT-file.
You need to define the InitialPosition and InitialOrientation. See the description of those name-value pair arguments on that documentation page to see what requirements (data type, sizes, values, etc.) those argument values must satisfy.
