Patent ID: 8243290

Claim:
A base point setting method for using a mapping analysis processing apparatus setting a base point to use surface analysis data, at a three-dimensional measurement surface which has an X-axis and a Y-axis in an X-Y plane with respect to a target surface and a measurement value axis Z extending perpendicularly to the X-Y plane at the intersection of the X-axis and the Y-axis and which specifies one measured value Z (x, y) for a position (x, y) on the target surface, the base point setting method comprising the steps of: setting parameters d and e such that the bottom of a hemisphere or semi-spheroid figure C [z≧0, f(x, y)=c{1−(x−d) 2 /a 2 −(y−e) 2 /b 2 } 1/2 ] contains a position (x i , y i ) where a base point should be specified, when a peak of the measurement surface occurs in the positive Z-axis direction; subtracting the height of the figure C from a measured value Z at each position of the bottom of the figure C, and expressing the minimum value of the differences as l min ; obtaining the height of the figure C at the position (x i , y i ) where the minimum value I min is obtained and adding the minimum value I min and the height of the figure C at the position (x i , y i ); shifting the figure C throughout in a range in which the bottom of the figure C contains the position (x i , y i ) and adding the minimum value I min and the height of the figure C at the position (x i , y i ), in the shifted positions; and expressing the maximum value of the sums as L (xi, yi) and specifying the base point at the position (x i , y i ) on the target surface as (x i , y i , L (xi, yi) ), wherein the parameter a is the X dimension of the hemisphere or semi-spheroid of the figure C in the X-Y plane; the parameter b is the Y dimension of the hemisphere or semi-spheroid of the figure C in the X-Y plane; the parameter c is adjusted in accordance with the shape of the surface of profile of the hemisphere or semi-spheroid of the figure C along the axis Z; the parameters d and e represent the center of the bottom of the hemisphere or semi-spheroid of the figure C in the X-Y plane; and the mapping analysis processing apparatus processes these steps.