Vaisala IRIS - Choosing Overlay Files; Overlay Overview; Invoking Overlay

10. Choosing Overlay Files
10.1 Overlay Overview
This utility is a legacy feature used when viewing radar data with IRIS Analysis.
When possible, Vaisala recommends viewing radar data with IRIS Focus.
You can use the IRIS Overlay utility to draw overlays or maps for display on top of other
IRIS/Open products. Overlays are used for product output and the real-time display.
An overlay can consist of the following:
• Geographical and political boundaries displayed with or without latitude and longitude
lines or range rings.
• Text strings to label areas of interest, such as cities.
• Bitmap Icons that can be constructed by the user and applied to the overlay. Icons can
represent any feature, for example, airports, train stations, and similar.
• The lines, text and icons mentioned above can be separated into dierent layers within
the overlay file. Then at display time, either all or only a subset of these layers may be
displayed giving yielding overlays that appear dierent based on which layers are
active. Layers can be drawn in dierent colors.
• Underlays are filled regions of color displayed under the radar images where there is no
weather data. Underlays are typically used to indicate areas of water.
Each overlay is defined in an ASCII file using a connect-the-dots approach (sometimes
called a vector approach). This allows overlays to be drawn to any scale factor.
You use the Overlay utility to create and modify your own overlays in a window on your
workstation.
Typically, you get the basic map (coastlines, borders, rivers) from Vaisala and then
customize it to meet your needs. It is often convenient to make separate layers for dierent
interests (river catchments, airports). IRIS supports up to 20 overlay files.
IRIS overlays are ASCII files so you can edit them with any text editor (vi, or emacs which is
distributed with IRIS).
10.2
Invoking Overlay
1. Invoke the Overlay utility by typing: overlay&
Overlay starts as a default with an empty window on your workstation.
Settings from your previous session are still valid when you restart.
Chapter 10 – Choosing Overlay Files
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