Map

Map

The map window will contain a graphical representation of data. 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.

Items can be displayed on the map by using the Display on map button in the map window. Other methods include:

• using the Display on map option when reading new data from files or the receiver,
• right-clicking on a name in an items list,
• using the Display on map option of the edit window for an item,
• using the display entry in the menu that pops up with Control-key left-click on a waypoint in the map.

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

• right-clicking on a name in an items list,
• using the Display on map option of the edit window for an item,
• using the clear entry in the menu that pops up with Control-key left-click on a waypoint in the map.

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 for the new waypoint will be the one in use for the map cursor coordinates. UTM/UPS 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. 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:

• all waypoints within a certain distance;
• all waypoints in the rectangle having as opposite corners this waypoint and a waypoint chosen from the menu;
• all routes containing this waypoint;
• all routes containing waypoints on the map.

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

• the Edit on map button from the route edit window; there must be at least one waypoint in the route; or,
• the Start RT entry of the menu corresponding to a mapped waypoint when no route is being edited; the route edit window will be opened and the waypoint becomes the route starting point.

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

• left-button on a waypoint adds it to the route; a waypoint cannot follow itself in a route;
• left-button where there is no waypoint, creates a new waypoint and adds it to the route; if the operation is cancelled the waypoints created this way will be discarded;
• left-button together with the Shift key removes the previous waypoint from the route unless there is only one;
• right-button stops the route definition from the map; if there is a waypoint under the cursor it will be added to the route, otherwise a new waypoint is created and added to the route; the route defined so far can now be further edited in its window;
• right-button with the Control key changes the insertion point to the previous stage, if there is one;
• right-button with both the Control and the Shift keys change the insertion point to the next stage, if there is one, or, when changing the last stage, to the end of the route;
• middle-button (or left- and right-buttons) with the Shift key cancels the definition; the same can be achieved by using the Cancel button of the route edition window.

The operations available from the menu (Control key and the mouse left-button 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):

• stop editing on the map, and either include the current point under the cursor (right click), or do not add any more points;
• cancel the whole edit operation (Shift and middle click);
• delete either the previous waypoint (the one before the current insertion point; Shift and left click), or the first waypoint of the route;
• edit previous stage, i.e., change the insertion point to the previous stage (Control and right click);
• edit next stage, i.e., change the insertion point to the next stage, if there is one, otherwise to the end of the route (Control and right click);
• add to end, i.e., change the insertion point to the end of the route (when editing the last stage, this can be done with Control and right click);
• close menu, destroying the menu-button.

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 menu-button, the mouse, the keyboard, or a wheelmouse.

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

Dragging the mouse with the middle button down 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
©Miguel Filgueiras, mig_at_ncc.up.pt, DCC-FC & LIACC, Universidade do Porto, 2002

Map