Most Rapid prototyping (RP) processes require the input model to be represented in STereoLithography (STL) format, which is actually an approximated B-rep representation. Approximation error is one of the major error sources of RP, which happens when an exact surface is tessellated from a surface model. Generally, the slicing algorithms are based on triangle-plane intersection algorithm. If a smaller approximation error is needed, the original surface must be tessellated with more mesh elements, which will take more time for the slicing algorithm. We investigate robust and efficient slicing algorithm for RP process which generates contours directly from the original input implicit representation models without any model representation conversion. Different from prior slicing techniques that tessellate implicit solid into triangular meshes and then intersected by slicing planes, we combine interval arithmetic, marching square method and bisection method to generate contour extraction on binary images sampled from given solids which has the topology preserved and the geometric error controlled to the smallest. Interval arithmetic increases the speed of the algorithm; topology is guaranteed by marching square method; bisection method guarantees function faithful. Moreover, since we do not need to generate the tessellated B-rep of given solids, the memory cost of our approach is low—only the binary image and the finest contours on one particular slicing plane need to be stored in-core.