A method for forming a three-dimensional object layer-by-layer comprising the steps of: a) forming bit-map data of cross-sectional layers of a three-dimensional object to be built; b) characterizing a light projector for its focus of pixels in an image area to control the width of light distribution of each pixel illumination of the object to be formed; c) characterizing the light projector for light intensity distribution versus gray scale levels in pixels in the image area and for illumination time of each pixel within the image area to control the amount of light energy delivered during an exposure to each pixel in the image area; d) delivering a solidifiable photopolymer build material to an imaging area; and e) projecting an image representative of cross-sectional image data from the light projector to illuminate pixels in an illumination pattern on an image plane exposure to selectively solidify the liquid medium, controlling with subpixel resolution the polymerization boundary of the solidifiable photopolymer build material in the projected pixels by applying different exposure parameters to different areas of the image plane, wherein the controlling with sub-pixel resolution the boundary polymerization of the build material is carried out by controlling the exposure in the image area either by varying the gray scales of the boundary pixels of the radiation source, by controlling the illumination time of different pixels differently, by varying the degree of focus of the pixels to control the width of light distribution of each pixel illumination or by varying the light intensity versus the age of the radiation source, or by combination thereof, thereby defining the object's borders, wherein multiple images for boundary pixels are not required; and f) repeating steps (d) and (e) for each cross-sectional image data until the three-dimensional object is built. a) forming bit-map data of cross-sectional layers of a three-dimensional object to be built; b) characterizing a light projector for its focus of pixels in an image area to control the width of light distribution of each pixel illumination of the object to be formed; c) characterizing the light projector for light intensity distribution versus gray scale levels in pixels in the image area and for illumination time of each pixel within the image area to control the amount of light energy delivered during an exposure to each pixel in the image area; d) delivering a solidifiable photopolymer build material to an imaging area; and e) projecting an image representative of cross-sectional image data from the light projector to illuminate pixels in an illumination pattern on an image plane exposure to selectively solidify the liquid medium, controlling with subpixel resolution the polymerization boundary of the solidifiable photopolymer build material in the projected pixels by applying different exposure parameters to different areas of the image plane, wherein the controlling with sub-pixel resolution the boundary polymerization of the build material is carried out by controlling the exposure in the image area either by varying the gray scales of the boundary pixels of the radiation source, by controlling the illumination time of different pixels differently, by varying the degree of focus of the pixels to control the width of light distribution of each pixel illumination or by varying the light intensity versus the age of the radiation source, or by combination thereof, thereby defining the object's borders, wherein multiple images for boundary pixels are not required; and f) repeating steps (d) and (e) for each cross-sectional image data until the three-dimensional object is built.