No, there are no limitations at all in the software, memory limiting. This basic principle of no limitations has been adhered to closely since the inception of the NuGraf and PolyTrans software.
If the texture bitmap is not in the directory specified by its filename and path then you have to explicitly tell NuGraf or PolyTrans where it is located. This is achieved by choosing the 'Configure File Search Paths' menu option under the 'File/Preferences' menu (in NuGraf) or 'Translate!/Preferences' menu (in PolyTrans).
Press the F2 key to make the message and error window visible. This window will contain all error and warning messages printed by the geometry import/export filters. In addition, these error messages are saved to the disk file "errors.log" located in the main NuGraf/PolyTrans distribution directory.
If the program should report an Out Of Memory condition during rendering then you will either have to increase the size of your existing swap file or buy more memory. It is extremely rare when any our customers run out of memory.
If you are importing from a large CAD file then: (1) make sure you have the "Topology = Bodies" radio button enabled for such importers as SolidWorks, Solid Edge, IGES or any of the Granite-based importers, (2) remove any useless/hidden assemblies in the source CAD program, (3) change the tessellation sliders found on most of the CAD importers, and to a less degree you can run the polygon reduction system which ships with all Okino software.