1. A three-dimensional model generating method utilizing a calculator that generates a three-dimensional model based on measurement data, which includes measurement point group data obtained by measuring a three-dimensional measured object, a type of a plane element, and geometric values of the plane element, the method comprising: scanning, via a coordinate measuring device, the three-dimensional object for obtaining the measurement data of a plurality of planes of the three-dimensional object, the measurement data including the measurement point group data, the type of the plane element for each of the plurality of planes of the three-dimensional object, and the geometric values for each of the plurality of planes of the three-dimensional object; displaying, on a display, a window with a listing of the plurality of planes of the three-dimensional object for selection; selecting, via the calculator, one of the plurality of the plurality of planes as a sweep base plane; selecting, via the calculator, another plane among the plurality of planes, the other plane defining contour lines and intersecting points based on the sweep base plane; generating, via a three-dimensional model element generator, a three-dimensional model element based on the sweep plane, the contour lines and the intersecting points as a sweep element, the three-dimensional model element representing a shape of at least a portion of the three-dimensional model based on the measurement data using a predetermined method, the three-dimensional model element being defined by a plane element and a predetermined condition; generating, via a three-dimensional model generator, the three-dimensional model using one or a plurality of three-dimensional model elements, the plurality of three-dimensional model elements including the sweep element; selecting, via the calculator and when generating the three-dimensional model, the predetermined plane element defining the three-dimensional model element from the measurement data; obtaining, via the calculator and when generating the three-dimensional model, the condition required to generate the three-dimensional model element; generating, via the calculator and when generating the three-dimensional model, the three-dimensional model element using the selected plane element and the obtained condition; and generating, via the calculator and when generating the three-dimensional model, the three-dimensional model of the measured object using one or a plurality of three-dimensional model elements.