vector drawings represent the &# 34 ; intelligence &# 34 ; content of images . a method is disclosed for the gathering of intelligence and the generation of vectors on the screen of a crt without the usual problems associated with cost and performance . the vector generator itself uses pairs of digital - to - analog converters with a common analog output . this technique is referred to as interpolation . careful shaping of the complementary reference voltages of the digital - to - analog converters results in constant velocity , transient - free vectors with starting and end points that are accurately controlled . cumulative errors are entirely absent .