A computer implemented method of fracturing free form target design into elementary shots for defined roughness of the contour comprises determining a first set of shots which pave the target design and determining a second set of shots to fill the gaps. The dose levels of overlapping shots in the first or second sets of shots are determined so the compounded dose is adequate to the resist threshold, considering the proximity effect of the actual imprint of shots on the insulated target. A dose geometry modulation is applied and rounded shot prints are produced by shots not circular that may overlap. The degree of overlap is determined as a function of desired optimization of fit criteria between a printed contour and the contour of the desired pattern. Placements and dimensions of the shots are determined by a plurality of fit criteria between printed contour and contour of the desired pattern.