This article outlines the capabilities of a scientific visualization toolkit called DataViewer, and compares it to analogous software. DataViewer was originally designed for the construction of the visualization part of certain computational steering packages, and consequently it is particularly straightforward to closely couple DataViewer with numerical calculations. Rendering is performed through a high-level scene graph which facilitates the easy construction of complex visualizations. DataViewer di#ers from other such libraries by allowing complex geometrical objects, which e#ciently encapsulate large amounts of data, to be used as nodes in the scene graph. Graphics hardware access is through the OpenGL API. Keywords---Scene Graphs, Scientific Visualization, Steered Computations. I. Introduction DataViewer is a scientific visualization library created to allow the easy development of e#cient visualization programs for those who are not, and do not wish to become, graphics progra..