Overlay File Formats:

This document describes the formats of the overlays associated with the “Data Driven Overlay” interface.

File Location and Naming

These files are contained in the $GRAPHICS_DATA_DIR directory. They following the naming convention overlay_### (for line overlays) and overlayicon_### (for icon overlays) where ### represents a number between 1 and 999. Note that other files are also stored in this directory. Please don't delete these other files, they have other uses (e.g. The default Earth background texture).

NOTE: The numbers identifying these files must be unique across BOTH the line and icon overlay files. Thus to have both overlay_1 and overlayicon_1 files in this directory WILL CAUSE PROBLEMS.

These files have different formats, as described below



Line Overlay File Format

First, any lines starting with “#” are comment lines and are ignored by the interpreter.

The first (non-comment) line in this file provides the color, line thickness and line type information. If the line thickness and type are not on this line they default to black and solid. Values are:

color – this either be the decimal equivalent of the RGB value of the desired color, or can be one of the following predefined values:

Line Thickness – in pixels

Line Type – Must be 0 (default) or one of the following colors

The second line is the description (free format)

The third line is of the format “Category: (category)” where the category is a free-format category title. Note that the first 10 characters MUST BE “Category: “ for this to be properly used. This includes capitalization.

The fourth line is of the format “Sub Category: (subcat)” where the subcat is a free-format subcategory title. Note that the first 14 characters MUST BE “Sub Category: “ for this to be properly used. This includes capitalization and the two blanks.

The following lines are of one of the following forms: 1) a comment line (starts with a “#”), 2) a blank line (used to indicate a break between multiple lines in the same overlay), or 3) a data line. Data lines contain 2 fields. These fields are the decimal latitude and longitude of the point.

Icon Overlay File Format

First, any lines starting with “#” are comment lines and are ignored by the interpreter.

The first (non-comment) line in this file provides the color, type, name, icon filename, scale factor, rotate flag and range_heading flag values of the icon. Details are:

An unlimited number of subsequent lines specify the location and (optionally) the name of each icon. There are two or three fields in each line. The first field is the decimal latitude, the second is the decimal longitude, and the rest of the line (or to 64 characters after trimming the whitespace) is used as the description. The description is optional and is used for map interrogations of the icon.