A computer-implemented method for simulating an image of a terrain scanned by a simulated radar beam generated by a simulated radar antenna, comprising: calculating on a first processor a power reflected by the terrain while an orientation of the simulated radar antenna is varied within a scanning antenna range; calculating on a plurality of second processors a convolution power for the terrain while the orientation of the simulated radar antenna is varied within the scanning antenna range, said calculating on a first processor and said calculating on a plurality of second processors being performed concurrently and in parallel; combining the power reflected by the terrain and the convolution power, thereby obtaining combined data; generating a radar image using the combined data; and outputting the radar image.