Topographic build plate for additive manufacturing system

A method of fabricating a 3D object using an additive manufacturing system, comprising:

• processing a computer model of the object to determine, with respect to a topographic build plate, X-Y coordinates of support structure for an overhang of the object;
• determining a Z-axis span of the support structure replaceable by offsetting an element of the plate, located at the X-Y coordinates, in a Z-direction with respect to other elements;
• and
• fabricating the object by offsetting in the Z-direction, as each layer of the object is fabricated, the element by a thickness of the corresponding layer until an amount of offset corresponding to the determined span is achieved.

A non-transitory computer-readable storage medium having an executable program stored thereon, wherein the program instructs a processor to:

• process a computer model of a 3D object to map a support structure for an overhang of the object to an element at X-Y coordinates of a topographic build plate;
• determine a Z-axis span of the support structure replaceable by offsetting the element in a Z-direction with respect to other elements;
• and
• before fabricating each layer of the object, control an elevator to offset the element further away from the other elements along the Z-axis by a distance of a layer thickness until an amount of offset corresponding to the determined span is achieved.