Orthorectification is the process of stretching an image to match the spatial accuracy of a map by considering location, elevation, and sensor information. To orthocorrect a raster dataset, the raster must have rational polynomial coefficients (RPCs) associated with it. For a more accurate result, use the digital elevation model (DEM) as well. 

http://gis.stackexchange.com/questions/118501/automatically-geo-and-ortho-rectify-raw-landsat-data-using-dem

http://gis.stackexchange.com/questions/78181/how-to-do-geometric-correction-of-remote-sensing-data-in-r

RPC file is the default control points provided with Cartosat 1 data by the data provider.  You can use this RPC file for your orthorectification process. But for better accuracy you have to collect more control points from field using Differential GPS.

Could you tell me the refinement of  RPCs with data collection  (differential GPS)