  Flatness measurement of a surface plate is an intensive and old research
topic. However ISO definition related and other measurement methods seem uneasy
in measuring and/ or complicated in data analysis. Especially in reality, the
mentioned methods don't take a clear and straightforward care on the inclining
angle which is always included in any given flatness measurement. In this
report a novel simple and accurate flatness measurement method was introduced
to overcome this prevailing feature in the available methods. The mathematical
modeling for this method was also presented making the underlying nature of the
method transparent. The applying examples show consistent results.
