The Tango Image Component contains the functions and events required to implement RGB Passthrough cameras in UE4 with the Tango. 
 
Note that the Tango natively returns textures in the YUV format, and so conversion to RGB by way of a custom material is required. Several helper functions have been included to assist with this task.

For more information read:

https://developers.google.com/project-tango/apis/c/reference/struct/tango-image-buffer