The following sections attempt to explain the most common functions of Prune, and how to use them. If you have any questions or feedback please use the email address at the bottom of the page.
Prune can read any text file as long as each line of the file describes a point, with the fields separated by a known character. The order of the fields must be consistent throughout the file, although several files of different formats may be loaded separately. Prune can't understand binary formats.
Opening a file consists of three steps: firstly selecting the file, secondly selecting the delimiter, and thirdly specifying which fields are in which order.
To access the function, select the "File" menu and click on "Open". Or use Ctrl-O from the keyboard, or the corresponding button on the toolbar. A file dialog will appear, with which you can choose the file to open. The first of the two dialog panels will then appear showing the first few lines of the file and offering a choice of delimiter (see picture below).
(2) First load panel for selecting file delimiter
(3) Second load panel for selecting
field combination and altitude units
Prune will attempt to guess the delimiter, but if it's wrong you can select one of the others, or enter your own in the "Other" box. Given the delimiter, Prune can then split the lines into a table on the second panel (see picture) and offer choices of fields. The fields are listed in the lower grid, with some standard fields (like Latitude, Longitude, Altitude) and also the option to define your own custom fields. You can change the definition of each field using a dropdown within the grid (eg click on Altitude to change it). You can also change the order of fields by selecting one and using the "Move up" and "Move down" buttons. The description column is for the custom fields in case you want to give the field a more meaningful name.
Also on this second panel is a selection for altitude units, giving the choice of metres or feet. Finally by pressing the "Finish" button the data will be loaded and displayed. If you find you have made a mistake with the field definitions, you can use the "Undo" function to remove the loaded data and try again.
To combine several files, simply load each one in turn. When asked whether to append the data to that already loaded, select "Yes" to add the data together, or "No" to remove the data previously loaded and just load the new file instead.
Opening an XML file is easier, as long as the file is in GPX or KML format. The function is started in the same way as for a text file described above, but an XML file is chosen instead. In this case you just need to select the file and the file should then be loaded automatically.
Screenshot showing selected point and range
After loading from a file, the data will be shown on the top-down map view and also (if it contains altitude data) on the profile view below. You can then select any point and view the details on the "Point details" panel on the right. There are several ways to select a point:
After selecting a point, this point may be deleted from the "Edit" menu under "Delete point", or using the keyboard "delete" key.
To select a range of points, use any of the methods above to select the start point, and then click the "Set range start" toolbar button or the "Set range start" function in the "Select" menu. This will select a new range from the current point to the end of the track. Now select the end point, and select "Set range end" (either from the toolbar or the menu). The range is now selected and the range details (including distance, time, altitude range etc) are shown on the right of the window.
To delete a range, make sure the range is selected and then use the "Delete range" function in the "Edit" menu.
To select the whole track, or to clear all selections, use the "Select" menu entries "Select all" or "Select none".
To delete all duplicate points in a track (points with the same latitude and longitude), use the "Delete duplicates" command in the "Edit" menu.
To delete closely-spaced points in a track to save space but retain detail, use the "Compress" command in the "Edit menu". This uses a variable parameter to offer different levels of compression - the default parameter of 100 gives reasonable compression, higher numbers delete fewer points and lower numbers delete more.
To add new points to interpolate between a pair of data points, select a range between the two points (so that only the two points are selected) and then use the "Interpolate" command in the "Edit" menu. Finally, choose the number of points to insert (calculated in an even straight line of latitude, longitude and altitude).
To reverse a section of the track, select it as a range and choose "Reverse range" from the "Edit" menu. This simply mirrors the order of the points so that the track goes in the opposite direction.
To undo any change made to the data, choose "Undo" from the "Edit" menu (or use the "Undo" toolbar button) and select the number of operations to undo.
The map view is zoomable to allow you to see the fine detail more clearly. The zoom and pan functions can be controlled either with the mouse or with the keyboard. To zoom in and out:
To pan the map up, down, left and right:
By default, the auto-pan function is switched on, so when you select a new point which is off-screen, the map will pan to bring it into view. To deactivate this feature, use the context menu on the map to deselect the checkbox for "Autopan".
To save the edited data, select "Save" from the "File" menu, or click the "Save" button on the toolbar. This brings up the first page of a 2-page save dialog, to allow you to select the options. The first page selects which fields to save and in what order, as well as the delimiter to use. The second, optional, page lets you specify any data format conversions to apply.
The field selection panel shows all the fields available, and whether they currently contain data or not. The third column of the grid lets you specify whether to save this field in the file or not. By selecting a row of the grid and using the "Move up" and "Move down" buttons, the order of the fields can be changed. The delimiter is selected in the same way as for opening a file, either using one of the listed ones or entering your own.
By clicking "Next", you can choose to select the format of the coordinates and altitudes to save in the file. By default just the values from the original file will be copied, but you may choose to convert to different units or formats.
The final step is to select the filename with which to save the data, which can be either a new file or can overwrite an old one.
There are two Xml formats supported by Prune, KML (used by applications like Google Earth) and GPX (used by many other programs). To export data in these formats, use the "Export KML" or "Export GPX" functions from the "File" menu. These Xml files don't support all the fields which a text file can contain, so make sure you save your data as a text file using the "Save" function if you wish to reload your data into Prune. Prune can read KML and GPX files but some fields may be lost in the translation.
To edit a point, firstly select it as described above. Then bring up the point editing dialog using the menu item "Edit point" in the Edit menu, or the "Edit point" toolbar button. In this dialog, each of the fields of the point (including any custom ones) are shown in a table. Select the field to change, click the Edit button, and enter the new value in the box. Repeat this for all the fields to change, and then click the "OK" button to confirm the changes.
If only the waypoint name needs to be changed, it's simpler to use the separate "Edit waypoint name" menu item instead - this is a simplified dialog with just the waypoint name editable. Functions for converting the name to upper case (eg "CHINZIG CHULM"), lower case ("chinzig chulm") or mixed case ("Chinzig Chulm") are also provided.
With a loaded track, select the menu item "Show in Three-D" from the View menu. This will open a new window containing the 3d display. Note that Java3D must be installed in order to use this function. This is an extra library which can be downloaded separately from the main java runtime. You can spin the model by clicking and dragging the mouse in the main window. To make a higher-quality rendering of the model, use the "Export POV" button on this display window to go directly to the Povray export function (see below).
Povray is an external program available for both Windows and Linux, which can make very high-quality renderings of 3d models. Prune can export your data into POV format, which can then be loaded into the Povray program. For more information about Povray and how to set the quality settings for good rendering, see the tutorials at povray.org.
To export in POV format, use the menu item "Export POV" from the File menu. This brings up a short dialog to set the font and the camera coordinates to use, and then allows selection of the output file. You can also bring up this dialog from the "Show in Three-D" function (see above).
Note that Prune does not invoke Povray directly, it just exports the data in the correct format. See the Povray documentation for how to call Povray using your platform.
To load photos, use the "Add photos" option on the File menu (also in the Photo menu), or use the "Add photos" button on the main toolbar. If the photos already have coordinate information in the exif tags, these will be read and new points created. If not, you can manually connect photos to points by selecting a photo (using the list box in the lower left), selecting a point (as described above) and then either using the "Connect to point" option from the Photo menu, or using the corresponding button on the toolbar.
If the track information has timestamps associated with the points (not all tracks have this information), then the automatic correlation function can be used to try to link the photos and points together. This works by matching the photo timestamps with the point timestamps. However, the camera's clock and the GPS receiver's clock are not perfectly synchronized, and in addition, the camera's clock is probably set to local time whereas the GPS receiver's clock is set using the satellites' signals in UTC time. So there is always a difference to add or subtract before matching the timestamps. The best way to figure out this difference is to manually connect at least one photo and then use that difference to correlate the others.
The correlation function is reached from the "Correlate all photos" item in the "Photo" menu. If at least one photo has already been correlated with a timed point, then a list is shown in order to select one. If not, the dialog jumps to the second step where the time difference can be entered manually. Limits can be set for the time between points or the distance between points to limit when photos will be correlated. Using the "preview" button, a table can be displayed showing which photos can be correlated using the selected time offset and limits. The checkboxes can be used to select or deselect photos, or the settings can be adjusted and another preview made. Finally the selected photos will be connected to the corresponding points (or new points will be created by interpolation).
After the photos have been correlated, the coordinates can be saved into the exif information of the jpg files (see below). Also, a KMZ including photo thumbnails can be created (see below), for example for showing in Google Earth.
Firstly, load and if necessary correlate photos as described above. Then select the "Export KML" function from the File menu. Make sure the "KMZ" option is checked, and the export image thumbnails option, and select the file to save. Then load this KMZ file into Google Earth to view. The thumbnails will appear in the description bubble for the points when clicked on.
The data can be further edited in Google Earth, for example by reordering waypoints, moving items into separate folders, associating "snapshots" with points, and editing the captions of the photos. The result can be saved again from Google Earth using the right-click menu.
To save the coordinates into the jpeg files, Prune uses an additional program called exiftool. This is based on perl and available for Windows, Mac and Linux. For Linux and Mac, you just need to install the exiftool package, but for Windows you get a zip file containing an executable called exiftool(-k).exe - you'll need to rename this to "exiftool.exe" and put it somewhere in the path - or edit the path to include the directory where you put exiftool.exe. This will allow Prune to find it at runtime. The about screen (Help -> About) shows whether Prune can find exiftool on your system.
To save the coordinates, correlate the photos either manually or automatically as described above, then choose the "Save to Exif" menu item from the "Photo" menu. A list of correlated photos will be shown, simply select the photos to save using the checkboxes and press "Ok". If the "Overwrite files" checkbox is checked, the photo files will be overwritten, which may be dangerous and could corrupt the file (although this is very unlikely). If this checkbox is unchecked, the original file is renamed with the extension _original and a new copy is made.