Digital Terrain Analysis (DTA), which can derives all kinds of topographic information widely used in diverse terrain-related geographic modeling and simulation, has been one of basic components of geo-spatial analysis, as well as one of fundamental functionalities of GIS. Researches on DTA methods have been continuously conducted in both width and depth. This paper tries to summarize the DTA researches from a new perspective, i.e., the dimensions of methodologic research on DTA. Three dimensions which successively emerged in methodologic researches on DTA are discussed, i.e., accurate, efficient, and easy-to-use. The dimension of "accurate" is of those researches on how to make DTA results more accurate. The dimension of "efficient" is of those researches on how to make DTA execution more efficient, or faster. And the new-emerging dimension of "easy-to-use" is on how to make DTA more easy-to-use in real applications as well as for users (especially those non-experts of DTA). The key study issue to be settled in the dimension of "easy-to-use" is how to formalize the knowledge on building DTA workflow properly and use it to conduct DTA during diverse real applications in an intelligent way. The proposed summarization on the dimensions of methodologic researches on DTA, as well as the corresponding methodologic researches, should be transferable for other domains in geo-spatial analysis, which often face the study issues similar to those in DTA domain.