cout << " --focal-length Focal length ratio (ratio to radius of phantom)\n";
cout << " (default = 1)\n";
cout << " --field-of-view Field of view (ratio to diameter of phantom square)\n";
cout << " (default = 1)\n";
cout << " --trace Trace level to use\n";
cout << " none No tracing (default)\n";
cout << " --focal-length Focal length ratio (ratio to radius of phantom)\n";
cout << " (default = 1)\n";
cout << " --field-of-view Field of view (ratio to diameter of phantom square)\n";
cout << " (default = 1)\n";
cout << " --trace Trace level to use\n";
cout << " none No tracing (default)\n";