GML Viewer User Guide

This is the latest version of the online User Guide. If the information here does not answer your question, why not try the FAQ page, if you can't find your answer in the FAQ, drop us an e-mail via the support page and we'll get back to you as soon as we can.

Getting started

When the viewer starts up for the first time, you will be asked to enter an activation code which should have been emailed to you after you successfully filled in the form available on the download page. After the initial launch you can run the viewer from a desktop shortcut.

To run the viewer from the desktop, single click the GML Viewer item to select it.

Pulldown Menu

File

File>Open - Launches the file dialog. Snowflake's GML Viewer has inbuilt support for Top10NL, AAA-NAS and OS MasterMap plus the ability to read any other GML2 or GML3 datasets stored using either: WinZip (*.zip), GZip (*.gz), or uncompressed file format (*.gml).

To load a known GML schema:

1a) Choose File>Open>Top10NL or File>Open>AAA-NAS, etc.

To load any other GML2 or GML3 data

1b) Choose File>Open>Other GML2 or File>Open>Other GML3

Then

2) In file dialog select the file you require and click Open. Initially the search criteria is set to *Zip, *.gz and *.gml, you can reset this to all files if you wish, using the pulldown at the bottom.

File>Unload - Unloads all current data, resets the application and frees all previously allocated memory.

File>Exit - Exits the current application and saves the file history. Note: you can close the main application window to exit the application, however, this does not save any accrued file history.

File History - The last item on the file pulldown is a 10 item file history. The file history is built up as you load file. Only when you use File>Exit will the file history be saved for a different session, otherwise, all file history accrued in that session will be lost.

Tools

The tools pulldown is another means of access the same functionality that on the tool bar. See ToolBar functions for more detail.

Window

The window pulldown allows you to manage multiple MapView windows

Window>New View - This is also available via the toolbar button for creating a new MapView

Window>Horizontally - Equally fit all the MapViews horizontally across the application window.

Window>Tile Vertically- Equally fit all the MapViews vertically across the application window.

Window>Tile Grid - Equally fit all the MapViews in a grid across the application window.

Window>Tile Cascade - Starting from the top left place one map view on top on another, move down and to the right enough distance to see all the MapView headers.

Window>Refresh All - Redraw all MapViews in the application

Options

Options>Set Selection Types - Allows the user to restrict what geometry types can be selected i.e. only lines.

Options>Set Display Quality>High - Set the display for high cartographic quality but slower redraw.

Options>Set Display Quality>Default - Set the display for default cartographic quality and faster redraw.

Options>Set Memory Usage >Default - All attributes of the file are loaded. Using this setting needs more memory.

Options>Set Memory Usage>Light - If the amount of data you load takes up more system memory than is available on your computer you may experience performance problems. Setting Memory Usage to 'Light' avoids loading of all attributes and more system memory is for displaying available.

Help

Various links to web site help pages and version identification

Tool Bar Functions

Zoom In / Out around the centre of the current MapView

Set the application into NAVIGATE mode with Zoom controls active on the cursor. When the Zoom controls are active the button will be greyed out. NAVIGATE mode places numerous navigation operations in control of the mouse and keyboard:

  1. Single left click to zoom in 10% and centre on point.
  2. Single right click to zoom out 10% and centre on point.
  3. Hold down Left mouse button and drag mouse to define a box. On release of Left mouse button MapView will zoom into the extents of the defined box.
  4. Hold down Right mouse button and drag mouse to define a box. On release of Right mouse button MapView will be adjust so that original view size will fit into the extent of the defined box.
  5. Holding down Shift key will make the Pan control active on the cursor. In Pan mode the cursor will change into a hand. Continue holding down shift key, using the left mouse button, click, hold down and drag the MapView to Pan in any direction .

Zooms the current Map View to fit the extent of all data currently loaded

Set the application into NAVIGATE mode with Pan control active on the cursor. Holding down the Ctrl key will make the Zoom control active on the cursor.

Pan Left, Pan Up, Pan Down, Pan Right. Pans the current map 80% in the relevant specific direction

Refresh (redraw) all current MapViews

Stops all redraw on all current MapViews

Launches the Attribute Browser and shows the attributes of the all the current selected features.

Some attribute values are marked blue, which means, that they show a link to another feature. Clicking on them creates a new table column with the linked feature and marks it on the display.

Set the application into SELECT mode. When in SELECT mode the button will be grey out. SELECT mode places numerous select operations in control of the mouse and keyboard:

  1. Single left click to select one feature only. When a different feature is selected the previous feature becomes unselected.
  2. Hold down the Shift key and use the left mouse button to select, whilst the shift key remains down features are added to the current selection.
  3. Hold down the Ctrl key and use the left mouse button to toggle a selected feature.

Clears the current selection i.e. deselects all selected features

Launches the Display by Theme dialog and allows the user to select which themes are to be display. Holding down the Shift key in the list dialog will select all items from the current selected to current cursor position where a left mouse click occurred. Holding down the Ctrl key will toggle the selection of a list item from selected to deselected. Use the Apply button the refresh the MapView according the current selection.

Launches the Display by Attributes dialog and allows the user to display features on the display according to their attribute values i.e. show all features with a Descriptive Group of 'Building' and an accuracyOfPosition of '1.0m'. Holding down the Shift key in the list dialog will select all items from the current selected to current cursor position and / or where a left mouse click occurred. Holding down the Ctrl key will toggle the selection of a list item from selected to deselected. The icons within the browser identify for attribute value and for geometry type.

Creates a new MapView with the same content and sizing as the current active MapView. You will be prompted for a name for the new MapView this will be display in the title bar of the newly created window.

Status Bar Functions

The status bar appears across the bottom of the main application window and is divided in 5 distinct sections

Cursor tracking

The cursor tracking part of the Status Bar allows the user to track the position of the mouse cursor in real world coordinates

With all tracking units, the user is able to enter a position, pressing the will centre the current MapView to that position.

Scale

The second part of the status bar shows the current map scale.

Hints

Next along from the Scale value is an information panel given the user context help based on the current active operation

System Mode

Next to the Hint panel is the current application mode, which can be either NAVIGATE or SELECT depending on the current active operation.

Load Mode

Finally on the far right the presence of a icon shows the viewer is currently set to Light Load mode.