Map background imagesUsing GPSMan in graphical modeSearching for data itemsMap


The map window will contain a graphical representation of data. Several operations on the map can be made using the mouse or the keyboard and a summary of these can be found below. The map window can be resized, but resizing is independent of rescaling (zooming) that is controlled by the Change menu-button.

Its contents can be saved as a Postscript file or further processed (e.g., printed) in Postscript -- cf. the "print command" option.

It is assumed that the user has chosen the relevant datum and projection before asking for some data to be displayed.

Some information that may be relevant for choosing a datum is given below.

The available projections and the way new projections can be defined are described below. Projections may have parameters, in which case they are computed either when a data item is displayed and the map is void, or when a map background image is loaded. According to an option the user is asked to accept or change them.

When a map background image is loaded it will be geo-referenced and a transformation of coordinates may be selected for that purpose. There are three such transformations: affine, which covers rotation and non-conformality, affine conformal, and affine conformal with no rotation, that corresponds to applying only a scale factor and that is used when there is no background image. Obviously there will be deformation when either the projection or the transformation is not suitable for the image.

More detailed explanations of how to use background images and projections and coordinate grids are given in the next sections.

Measuring distances and azimuths on a non-empty large-scale map can be done by using the mouse right-button when pressing the Shift key to select a sequence of positions (at a distance greater than 1 metre). Arrows between each position to the next will be displayed and a dialog will show the total distance and the azimuth of the last position from the first. The arrows will be deleted when the dialog is closed. The dialog allows for the line formed by the arrows to be closed (linking the last position to the first, unless they stand at less than 1 metre) and to be used in creating a polyline item (LN). Note that distance values computed in this way can be wrong on small-scale maps if two consecutive points are too far away from each other.

Items can be displayed on the map by using the Display on map entry in the Items menu-button in the map window.

If the item has an associated map background image name and the map window is empty the image will be loaded before displaying the item. If the name refers to a non-existing or invalid file, it will be silently ignored. Please see below for further details on how to define map background names.

Other methods include:

To clear an item from the map there is the Clear entry in the Items menu-button in the map window. Other ways of achieving the same effect:

Groups can also be created for the items that are or are not currently displayed on the map. This is done using the Make Group entry of the Items menu-button on the map window.

A waypoint can be created on the map , if the map has been geo-referenced, by clicking with the mouse left-button on an empty place, or by using the Return (or Enter) key. This can only be done when no waypoint is being edited. When a route is being edited on the map the Return key has no effect, and the left-button on an empty place creates a waypoint that is added to the route (see below). The position format and datum for the new waypoint will be the one in use for the map cursor coordinates. Decimal degrees (DDD) will be used instead when the position is out of the range of the selected grid. To finely position the cursor, the arrow keys for scrolling the map and the Return key should be used instead of the mouse.

A menu-button for a waypoint on the map will be created by pressing the Control key and clicking on the waypoint with the mouse left-button in Unix/Linux systems, or only the mouse right-button in other systems. It will allow for moving the waypoint (i.e., changing its position), starting the definition of a route (see next paragraph), or for displaying or clearing:

A waypoint that is being moved is placed in its new position by using the mouse left-button. The right-button cancels the operation. A balloon will show the possible actions.

A route can be changed or created on the map by using

In either case, changes made on the route on the map will appear in the route window. The cursor will show the current insertion point that at first is the end point of the route, but that can be moved to in between any two waypoints of the route (if there are as many) -- this may be seen as changing the corresponding route stage.

Edit operations are performed by using the mouse buttons and the Shift and Control keys, and/or by using a menu that will appear by pressing the Control key and clicking the mouse left-button (not on a waypoint!).

Clicking with the mouse

The operations available from the menu (Control key and the mouse left-button in Unix and Linux systems, or only the mouse right-button in other systems, not on a waypoint) are the following (only those that are meaningful will be shown at any given moment; the corresponding shortcut using the mouse/keyboard is shown if there is any):

When using Control-right click and Control-Shift-right click to go from one stage to another the lines in the map are only redrawn when the cursor moves.

During the edition of the route, waypoints can be moved to other positions as described above.

Scrolling and panning the map can be done by using the Locate entry in the Items menu-button, the mouse, the keyboard, or a wheelmouse.

Selecting an item with the Locate entry in the Items menu-button (only items on the map are listed) scrolls the map so that the selected item becomes centred. In case of a route, track or polyline this applies to its first point.

Dragging the mouse with the middle button down or moving it with the Control key pressed will pan the map.

The keyboard arrow keys and the Space and Delete keys scroll the map in the expected way, while the arrow keys with the Shift key scroll the map in the SE-NW and NE-SW directions.

Users of a wheelmouse can use the wheel in it for the same purpose: with no modifier key for vertical motion, with the Shift key for vertical motion by one page, with the Alt key for horizontal motion, and with the Control key for horizontal motion by one page.

As the cursor coordinates are updated when the cursor moves, the use of the keyboard for scrolling is also a means for finely positioning the cursor.

Reading items that are on the map will update the map, so that the items are shown according to their newly read definitions.

GPSMan User Manual
Copyright 1998-2013 Miguel Filgueiras,

Creative Commons License
GPSMan User Manual and the GPSMan logo images by Miguel Filgueiras are licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.

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Map background imagesUsing GPSMan in graphical modeSearching for data itemsMap