So it has to be practical and this is related to the user intervation we want to make sure that when the user gets involved things get better because of the involvement of the user and don't get worse so we don't want the user to basically say oh, I'm happy with everything but this and then the user go goes and does something that basically destroys the part that he or she was already happy with so it has to be a natural work flow and very easy and as we say has to be very computational efficiency so you know we have about 30 frames a second in the NTSE American system our, our and similar you know 24 to 30 frames between the empty seat and polly systems and we don't want every frame to take hours we just want every frame to be done really kind of in an interactive comfortable time. 