An object interference checking technique using height maps, for machine tooling and other applications. A CAD model of a workpiece or other obstacle is converted to a height map defining obstacle height above a plane of a reference frame for each cell of a grid. A machine tool center point path is then transformed to the same reference frame. Interference checking is performed by comparing a height coordinate of each transformed tool path check point to the height map value for a corresponding grid cell. Any interference that is detected is addressed by defining new path points with increased height coordinate to replace the interference-critical path points. An entire tool can be interference checked by creating a bottom-up height map of the tool and comparing each pixel of the tool height map against the corresponding grid cell of the obstacle height map.

A path generator includes an object setter that sets an object model; a device setter that sets a device model as a model of a robot arm; a path generator that generates a path of the robot arm stepwise; and an interference determiner that performs interference determination on the object model and the device model after having moved along the path, based on a distance between the object model and the device model. If it is determined that there is a possibility of interference between the object model and the device model, at least one of the object setter or the device setter increases a density of point groups of the point group model, and performs interference determination by using the point group model with the increased density of the point groups. If determined that that there is no possibility of interference, the path generator generates a next path.