Aiming at different application needs, this paper presents a classification taxonomy, in which these applications are fallen into 4 categories: Delayed coverage of sensor being higher than or in target region, non-delayed coverage of sensor being higher than or in target region. Taking factors of sense regions and possible ones into account, it proposes different sensing models depending on different applications. Based on the above mentioned, themodels and nodes deployment methods are analyzed. The results indicate that the proposed sensing models and estimation methods agree with actual application than previous approaches.