|MapGazer – Using Areas|
An area is a mark that defines a rectangle displayed on a map; it can be used to create an image from a map (which can be much larger than a screenshot) or to save a subsection of the map (for example for a smartphone with limited storage capacity).
To create an area, you can:
Any of these will show the border of the new area within the current window; you can then left-click on any edge or corner of the border and drag it to adjust the area covered. The coordinates of the area’s SW and NE corners will be shown at top-left of the map when the cursor is over, or dragging, the border of the area (you can turn these off using the Settings → Status display → Show area coordinates menu item).
An area is not affected by zooming, so you can zoom in to position it accurately. You can also open one or more extra windows (press ‘v’) and then use the windows to zoom in on different edges of the area.
You can also create an area at the bounds of the map by selecting the Marks → Add new area at map bounds menu item. This creates an area at the bounds of the most detailed (highest zoom) map layer so you can see where those bounds are when zooming out, and gives the area the same name as the map. Note that some maps have irregular (non-rectangular) boundaries so parts of the map within the bounds could be missing.
You can change the properties (name, colour, link URL, etc.) of an area by right-clicking on the area border and selecting Properties; for more details, see Mark properties. You can change the displayed width of area borders and other marks using Settings → Line widths.
Even if not displayed, you can view the area’s coordinates, and copy details to the clipboard for use by another application, by right-clicking on the area border and choosing the Details menu item.
To change the format used for Latitude and Longitude, select Settings → Position formats on the menu bar; see the General settings page for details.
To create an image from a map, create an area then select Save area as image from the pop-up menu displayed by right-clicking on the area border. This will display a save dialog which lets you select the folder and enter the name for the new image.
Images include visible marks and are saved in Portable Network Graphics (PNG) format; after the image is saved it will be opened (using the current viewer for PNG files) so you can check it, save it in a different format, print it, etc.
You can inspect the dimensions of an area in pels (image pixels) at the current zoom using the Details dialog (see above).
To save a subsection of the map, create an area then select Save area as map from the pop-up menu. This will display a dialog showing a folder tree (usually including the parent of the current map). You should normally enter a new name for a folder into which the map will be saved, then press OK.
This saves at least the tiles from the source map that overlap or are within the designated area. All layers in the source map will also appear in the saved map (i.e., the area saved is not zoom-dependent).
The target folder (map) may already have data. In this case the target map must be compatible (that is, have the same number of tiles per file), and the source tiles are merged with (added to) the tiles within within the target folder.
If both source and target contain the same tile then the larger tile is used (written) on the assumption that more information implies less omitted/blank area. If both are the same size (unlikely, if different) the source tile is used.
Note, however, that merging maps from two different sources may cause problems as tles may be in different formats. To try and alleviate problems the stub for directories is taken from the name of the parent folder (the map name) – this works well with MyTrails, too.
Merging maps cannot take note of the pixels within a tile. Hence if two tiles with different blank areas are merged the resulting tile will be one of the two and will have a blank area.
To move between areas (if you have more than one area loaded or created), either
In either case the order used is the chronological order in which the areas were loaded or created.
Areas can be saved to or loaded from GPX files:
To save an area definition right-click on the area border and select Save area coordinates to GPX file on the pop-up menu. Alternatively, all marks (including all areas) can be saved using the Marks → Save marks to GPX file menu item (or press the ‘s’ key).
To load a GPX file, use the Marks → Load marks from GPX file menu item (or press the ‘L’ key). This will open a dialog which you can use to select the GPX file to open. Any marks (tracks, routes, waypoints, and areas) in the file will then immediately be shown on the map (you may have to zoom or change the map, or move it, for the marks to be in view).
Depending on the source of the GPX file, areas may have a default (red) colour or may have a colour that was selected at the time the area was created.
If an area has been loaded from a GPX file it can be adjusted as described above. At any time you can reset an area loaded from a GPX file to its original data by right-clicking on the area border and selecting Reset area.
To delete an area, right-click on the area border and select Delete area on the pop-up menu.
|MapGazer and these web pages were written by Mike Cowlishaw; Please send me any corrections, suggestions, etc.|
All content © Mike Cowlishaw, 2014–2017,
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This page was last updated on 2017-02-19 by mfc.