We study triangulated surface models with nontrivial surface metrices for membranes. The surface model is defined by a mapping
from a two-dimensional parameter space M
to the three-dimensional Euclidean space
. The metric variable
, which is always fixed to the Euclidean metric
, can be extended to a more general non-Euclidean metric on M
in the continuous model. The problem we focus on in this paper is whether such an extension is well defined or not in the discrete model. We find that a discrete surface model with a nontrivial metric becomes well defined if it is treated in the context of Finsler geometry (FG) modeling, where triangle edge length in M
depends on the direction. It is also shown that the discrete FG model is orientation asymmetric on invertible surfaces in general, and for this reason, the FG model has a potential advantage for describing real physical membranes, which are expected to have some asymmetries for orientation-changing transformations.