Abstract: A method is described for improving the responsiveness and accuracy of a graphics system to user-initiated picking actions. In this method, the visual cueing and pick window positioning components of the graphics system tracking/picking function are temporarily separated at the time the user attempts to pick. By handling these two components of the tracking/picking function independently, both type 1 (failure to pick the desired item) and type 2 (picking an undesired item) errors are prevented. This translates into greater productivity for the graphics system user.

Abstract: In graphics display systems the use of matrix concatenation for coordinate transformation, occasionally, will cause an overflow which may represent an out-of-bounds location of a data element. To correct the overflow problem, a number of translation shift factors are introduced for the last row of the matrix which when used to operate on matrix elements, will maintain the elements within the physical boundaries of the graphics base by preventing overflow. Additionally, a method of adjusting the clipping boundaries to increase the precision of coordinate transformations is also described. The methods of the invention may be implemented in microcode in a commercially availably graphics display system such as the IBM 5080 Graphics System.