In this paper the modeling and measurement of local flame surface orientation in turbulent premixed flames have been presented. The measurement is based on laser sheet tomography (LST) technique. A model is introduced to recover the information loss, which is caused by the inability of the two dimensional LST technique in resolving the local flame surface orientation. It is found that an underestimate of 19% may exist in evaluating the flame surface to volume ratio Sigma if the assumption is made that all flame surface orientation vectors are in the LST plane. The present work makes a first attempt in combining modeling technique with measurement in recovering information loss. The study may have strong implication to general two dimensional diagnostic techniques.