The Astra and Astra S (And their respective mini models) only get their color stream from OpenNI or AstraSDK. The Astra Pro model, includinc Persee on the other hand, cannot get their color stream from OpenNI or AstraSDK, since the color stream is an standard UVC stream, and as such you can use any library or software compatible with UVC web cameras.
If NiViewer shows the color stream, it means that you are using a non Pro version of the Astra cameras, and as such you are unable to use it as an strandard UVC stream.