1. A method for processing ultrasound data as a function of a surface, the method comprising: writing to a depth buffer of a graphics processing unit as a function of first ultrasound data, the first ultrasound data representing samples in a volume of a patient; processing second ultrasound data as a function of data from the depth buffer, the data of the depth buffer indicating the surface, the first ultrasound data being the same or different than the second ultrasound data; generating an image as a function of the processed, second ultrasound data; and identifying the surface from the data from the depth buffer and determining an orientation of the surface relative to an insonification angle, and wherein processing comprises varying an M- or B-mode imaging parameter as a function of a cosine of difference of the insonification angle and the orientation.