Plot Mode

Plot mode displays a zoomable vector map of the world with optional feature names (2861 cities, 194 countries, 233 islands, 62 lakes and oceans).

The pen can be used for zooming, panning, measuring distance and for switching place names on and off.

The Tool Button shows the current pen tool. Tap on the Tool Button to cycle between the different tools: Measure Pan Select Zoom The Tool Button can dragged the most convenient position for you.	Capital cities are drawn with bigger dots than non-capitals.   Individual city and country names can be toggled on and off by tapping on them using the Select tool ().   Lat/Lon grid lines (the graticule) and their labels can be turned on and off in Preferences Mode.
Country names are written in all capital letters. You can use 2 letter codes to save screen space.	Land/water borders are drawn with solid lines, political borders are drawn with dotted lines.

You don't have to wait for the map drawing to complete before using the tools, menus or hardware buttons. Whilst it is drawing, the program periodically checks for user input.

Pan The Pan tool scrolls the map up, down left and right. Drag a point to a new location, the map will be redrawn with that point moved to the final pen position. A crosshairs shows you where the pan will end.

Zoom Drag downwards to zoom in, and upwards to zoom out. The new view will be centered at the point where the drag starts. An outline of a box shows you what will happen when you remove the pen. When zooming in, the new map will be the area inside the box and when zooming out, the current map area will be shrunk to fit into the box.

You can also assign zoom and pan functions to the hardware buttons using the Special menu (in Preferences Mode).

Measure As you drag the pen from one point to another, a popup box displays the distance from the start point to the current pen position. Use Preferences Mode to select between miles, kilometers or nautical miles.

Select Toggle labels on an off by tapping on them. As you move the pen, it's coordinates, and the distance to the nearest feature label (city, country, island, lake or ocean) are displayed in a popup box. Lifting the pen `selects' the nearest label, displaying it (or hiding it if it is already selected).

Labels displayed because they have been `selected' can only be turned off by selecting them again. They are not controlled by the settings in Preferences Mode. To deselect all labels, use the Special menu. Similarly, labels displayed because they have been enabled in Preferences Mode cannot be deselected using the Select Tool.

Use the hardware menu button to activate the Plot Mode menu.

There are three dropdown menus, the first Mode selects the main functions of CITYZEN:

Find... Find things in a sorted list Quiz... Control the quiz settings, start and stop the quiz Prefs... Define what features will be shown About... Display application and version information

The second menu, View has three options:

World Go to the world view Home Go to the home view (set using Special Menu) Go back Return to the last view (the last 32 views are kept)

The final dropdown menu, Tool lets you select any of the Pen Tools.

Zoom ...in or out Pan ...the view around Measure ...distance between two points Select ...a feature (toggle labels)

Map accuracy

CITYZEN uses a unusual projection, in that it transforms the world map into a square. Whilst this neatly fills the screen, and is easy to calculate, it produces grossly distorted maps. The errors are greatest at the poles. Do not be fooled by the size and shape of countries, warping the surface of a sphere into a square will make places look bigger or smaller than they actually are.

The measure tool generates distances using the Great Circle formula. This calculates the shortest distance between two points on a sphere. CITYZEN does not compensate for the fact that the Earth is not a perfect sphere, so distances (especially those parallel to lines of latitude) will be subject to some error.

The 20,379 line segments used to represent the world have been produced by under-sampling the 125,795 line segments in the World databank I. The undersampling algorithm was not particularly clever and has completely removed many small (less than about 100 miles) features from the map.

The world has been digitised onto a 32400x32400 grid. This means that the highest possible resolution of the outline and place databases is about three quarters of a mile (just over 1 kilometer). Detail smaller than this (that has survived the undersampling process) will not be visible.