ABSTRACT
This chapter addresses the basic approaches to visualizing spatial heath data on R. It considers first three-dimensional surface visualization and surface drawing, followed by tools for thematic mapping and finally considers some special health applications. R has a wide range of packages for specialist plotting. The chapter focuses on the akima and mba packages and the image, contour, persp, and filled.contour commands. The akima package is a basic package which includes facilities for the interpolation of randomly located spatial data. The discrete nature of disease risk coupled with the need to represent spatially aggregated data leads to the consideration of thematic mapping. More specifically, choropleth mapping is a special form of thematic mapping where color gradation is used to depict different levels of the variate of interest. The primary role of a polygon object is to provide a graphical representation in conjunction with a mapping function.
