INTRODUCTION

In SEP-61 I described the X3D graphics system--XWindows, extensible, three-dimensional graphics system for geophysical data visualization. Its purpose was to bring usable 3-D graphics to SEP in two forms: canned programs that can read and plot standard SEP datasets and a set of subroutine libraries for easily writing new programs. X3D was motivated by that existing visualization packages require special hardware generally inaccessible to SEP and are not easily integrated into SEP's processing system.

The properties of X3D include:

• Three-dimensional vector and raster (new) graphics models.
• Extensibility. One can create new applications by adding custom parts to the generic system.
• Portability. X3D is written in XWindows, XView, vplot, and SEPlib and runs on all our computers.

There are two kinds of improvements to the version of X3D described in SEP-61. First, the user interface was upgraded from menus to control panels. This was made possible by a standard control interface called XView in the current release of XWindows (11.4). Second, new graphics abilities such as lighted surfaces and transformable raster arrays were added.