1 Introduction

AGI is a graphics database system. It can be used to store information about the size and position of a plot on a graphics device. This can be used by subsequent applications to find out where the plot has been drawn and how the coordinate system maps onto the plotting area.

One obvious use of the database is to allow an application to overlay its output on top of that produced by a different application, for instance plotting radio contours onto an optical image. The first application draws its image and informs AGI the size and position of the plot. The second application uses AGI to set up its graphics coordinate system to match that of the first application so that the contour map appears in the correct position on the screen.

Another common use is to allow an application to put up an interactive cursor to read off positions from a previously drawn image.

Although designed for use within ADAM, AGI can also be used in non-ADAM applications.