Recent research literature on sensor network databases has focused on finding ways to perform in-network aggregation of sensor readings to reduce the message cost. However, with these techniques information about the state at a particular location is lost. In many applications such as visualization, finite element analysis, and cartography, constructing a field from all sensor readings is very important. However, requiring all sensors to report their readings to a centralized station adversely impacts the life span of the sensor network. In this paper we focus on modeling sensor networks as a field deployed in a physical space and exploiting in-network surface simplification techniques to reduce the message cost. In particular, we propose two schemes for performing innetwork surface simplification, namely (1) a hierarchical approach and (2) a triangulation based approach. We focus on a quad tree based method and a decimation method for the two approaches respectively. The quad tree ba...