Bringing detail-in-context viewing & data manipulation to online data sets

LookWMS was developed by IDELIX and implements the OpenGIS® WMS specification combined with GeoTIFF.  LookWMS is powered by Pliable Display Technology (PDT) and demonstrates the access of geospatial data over the Internet combined with local GeoTIFF images while providing PDT's detail-in-context viewing capabilities.

LookWMS provides the user with the ability to view different layer combinations: one combination can be viewed inside the lens region, while a completely different combination can be viewed outside the lens in the base map region.  The layer combinations can be created from one server, multiple server connections, or GeoTIFF  file and servers. This enables faster and easier comprehension of high-density data sets as users can focus their eye on areas of interest and avoid the feeling of data claustrophobia.

IDELIX LookWMS Quick Start Instructions

Below is a brief description of how to interact with LookWMS.  We strongly urge that you read these instructions and explore the full capabilities of the applet before using it.

The Map Window

 

  WMS Server Chooser

The WMS Server Chooser button brings up the WMS Server dialog box.  Use this dialog box to Select, Remove, and Delete servers from the currentl list.  Use Add and Edit to add new servers to the list. With LookWMS, it is easy to connect to multiple servers at one time.

Once a connection is made, a list of the possible layers will appear in the Layers window.  Check the layers that you wish to view, then click on the Retrieve/refresh map button.  The server will create a map based on the selected layers and return the appropriate map in the Map window.

  Open/Close GeoTIFF

GeoTIFF files can also be viewed using LookWMS.  Use the File->Open GeoTIFF option to load GeoTIFF images stored locally.  Only one GeoTIFF image can be viewed at a time, with or without WMS server layers.  If a GeoTIFF image is already being viewed, then calling on Open GeoTIFF will replace the currently viewed GeoTIFF.  Use the Close GeoTIFF button to remove  the currently viewed GeoTIFF.

  Retrieve Map after adjusting Data Layers

Data can be selected or deselected by clicking on the boxes located in the Base and Lens menu tabs located within the Layers window on the left side of LookWMS.  With LookWMS, it is possible to create maps with layers from different servers.  The example below shows a tree list view of layers selected from two different servers:  WMS Demo server and Atlas of Canada.  Layers are requested from the Layers window reading from top to bottom which means that, for example, the first selected layer is drawn first and subsequent selected layers are drawn on top.

 

Since the layer order affects how the server generates its map, LookWMS makes it possible to rearrange the server and layer order by simply dragging the server or layer up or down the tree list.  In the example above, the left view indicates a request from the WMS Demo Server followed by Atlas of Canada.  On the right, the request order is reversed.  Moreover, the layers example on the left requests the Elevation layer prior to the Cities layer.  On the right, this request order is reversed.

After you have selected your data layers for both the Base region and Lens region, click on the Retrieve map button to update the data set with your selected viewing preferences. 

  Stop map retrieval

Use the Stop map retrieval option to stop the current download.  Any data that has been downloaded before Stop is pressed will become visible.  This button is useful if you have selected the wrong layers and want to stop the download process.  After pressing Stop, set up your layers as desired and press Request/refresh map once again.

Customize the lens layer

In the default case, the layers seen inside the lens follow the layers selected for the base.  As a result, the layers inside the Lens tab are disabled.  To view layers inside the lens that are different from the base layers, click on the Customize check box found at the top of the Lens tab. 



Notice the additional slider that appears below the lens when the lens and base layers are not synchronized.  Use this slider to blend data inside the lens region with data outside the lens.

    Apply a PDT Lens

There are three PDT lens shapes to choose from: The PDT Pyramid lens, the Cone lens, and the Circle-Square lens.  To add a PDT lens, left-click on the button that corresponds to the chosen viewing shape. The lens shape that appears within LookWMS can be easily changed by selecting the desired lens button located in the tool bar.
 

  Activate & Manipulate the Lens

Once the base and lens data layers have been selected, click Activate Lens mode in the tool bar to activate the lens controls. Left-click and drag with your mouse anywhere within the lens to move the lens.

Redrawing Note: When the lens is first moved to a new location, the magnified section of the map needs to be redrawn. To reduce the amount of time spent waiting for a single map request, LookWMS requests higher resolution or magnified portions of the map in tiles depending on where the PDT lens is located on the map.   That is, the lens only fetches the tiles it needs for the area covered by the lens.  This approach saves time by delivering only the area needed instead of fetching the whole map.  To fetch the lens detail for the whole map, click on Map->Retrieve all lens layer data.
 

  Adjust Lens Size, Shoulder, and Magnification

Control the PDT lens with the in-place Modular Design Lens Configuration (MDLC) handles and sliders. The lens magnification, position, and size can be manipulated with the MDLC user interface.  The focal region and base sizes can also be changed by clicking and holding the left mouse button down and dragging the respective handles that surround the focal and base regions.
 

Blend the data inside Lens

Once the cursor changes to the blend icon, click and hold the left mouse button down and drag on the bottom slider to blend the lens layer with respect to the base layer.  The resultant view inside the lens is a blend of the lens and base layer images.

Blending inside the lens allows you to inspect the lens layer combined with the base layer.  The blend slider is only visible when the lens layer differs from the base layer.

  Blend Context Map Data

There also exists a slider to blend the context data, or the data outside the lens.  This Map blending slider appears just below the Map window and is only visible when lens and base layers differ. 

  Remove the Lens

To delete a lens and view data in an undistorted state, simply left-click on the Hide PDT lens button located in the tool bar next to the Show PDT lens shape button.  A lens can be re-added by clicking on the desired lens shape button.
 

   Save screenshot

This option allows you to take a snap shot of the Map Window.  By selecting the Save screenshot option, you can export the view of the data set that appears within LookWMS Map Window to a JPEG format.  If there is a PDT lens visible on the data appearing within the window, this lens will also appear in the exported JPEG image.  If the map has been modified using the markup tool or text tool, then these markups will also appear in the saved JPEG file.

Save screenshot is different from Save GeoTIFF.  A GeoTIFF is a geographically referenced file that can be opened with LookWMS or any other GeoTIFF viewer.  JPEG images can not be opened with LookWMS.  When saving a GeoTIFF file, both the  map data and the lens data are saved, but not the lens itself.  Thus, a lens can subsequently be used to explore the image.  With a JPEG file, a static lens is burned into the image.

Copy

By selecting the Copy option, you can copy the view of the data set that appears within LookWMS Map window to the clipboard. If there is a PDT lens visible on the data appearing within the window, it will also be copied to the clipboard.  If the map has been modified using the markup tool or text tool, then these markups, too,  will also be copied to the clipboard.

   Save GeoTIFF

Select the Save GeoTIFF option to save the data set that appears within LookWMS Map Window as a GeoTIFF file.  If the map has been modified using the Markup tool or Text Annotation tool, then these will also appear the next time this saved GeoTIFF file is opened. 

After pressing the Save button, a dialog may appear questioning the user about downloading any missing data.  The missing data refers to the lens data since it is at a greater magnification than the base data.  In general, the lens data is retrieved piece by piece as the lens moves from one location to another over the Map window.  These pieces are put together and stored in a lens buffer so that when the lens revisits an area, data does not have to be re-retrieved.  Answering with yes to this dialog box question will ensure that the lens buffer is complete before saving.

  Pan the image

Use the Pan button to click and drag the map in any direction.  Left-click on the Pan button located in the tool bar.  Once this tool is selected, the cursor will change to a hand.  Hold the left mouse button down and drag the data in any direction to suit your viewing needs. To re-activate a PDT lens, simply click on the Activate Lens mode, found in the tool bar.
 

   Zoom in and out

Use the Zoom in and Zoom out buttons to select your view.  Select the appropriate tool by left-clicking on the button in the tool bar.  Once one of these tools is selected, the cursor will change to the respective zoom tool.  Hold the left mouse button down and draw a rectangle around the region that you wish to zoom into or out of.  You may also simply click in the area of interest to zoom in or out.  To re-activate a PDT lens, simply click on the Active Lens mode, found in the tool bar.
 

    Map markup

Four tools are associated with marking up a map: Mark up, Undo markup, Redo markup, and Delete all markups.  In Markup mode, lines, circles, crosses, etc, can by used to annotate features on the map. 
 

    Text annotations

In Text mode, letters, or text, can be added to the map.  Click on the tool, then click on the map where the text should be displayed.  A box appears into which text can be typed.  To delete text from the map, click on the text, and press the delete key.

Retrieve all lens data

While interacting with the lens, the lens retrieves data from the server every time it visits a new location on the map and stores it in the cache in case it ever visits that location again.  If the System Preferences for the cache are set to Automatically retrieve high res data, then data for the lens will be retrieved and stored in the cache while LookWMS is idle.  To retrieve the lens data for the current map view explicitly in one download, use the Retrieve all lens data menu item under the Map menu.  After performing operations that reset the map view and lens cache, such as changing the lens magnification, changing layers, and zooming in or out, users should select the Retrieve all lens data button again in order to refresh the memory cache.   If dealing with large data sets, users may also want to increase their image cache  size in order to avoid running out of memory before retrieving all lens data.

      Online Offline indicators

The status bar along the bottom of LookWMS includes an online/offline indicator.  If the lens data has not been retrieved before going offline (see the items under the File menu), then the user is asked if any missing data should be retrieved first.  After going offline, the status bar displays an open connection and LookWMS will no longer make server requests.

Status bar messages

The Status bar provides the user with some basic feedback such as when LookWMS is busy downloading data, caching data, has problems retrieving data, or is idle.

Edit Preferences — Appearance

The Appearance tab inside the Edit Preferences dialog box provides a number of options to change the general appearance of LookWMS including the map window background color, the color of the lens handles, the markup color, and the text annotation color. 




The Show legend symbols checkbox refers to enabling and disabling the icons associated with the various layers.  The example below shows the layers with legend symbols turned on.  It also shows the context menu associated with the Crosshair layer (just below the Lat/Lon Graticule layer).  Turn these options off if you are struggling with a shortage of memory on your computer.

Edit Preferences — Cache

The Cache tab under the Edit Preferences dialog box provides a means to set the cache size on your machine.  This sets a limit on the amount of image data that LookWMS can cache.   If you are experiencing black tiles in the map or lens region, or 'out of memory' messages are appearing in you Java console, increasing the Image cache size setting, and re-starting LookWMS may help.  Reducing the magnification of the PDT lens may also help.

Operating LookWMS is optimal with a large cache size setting.  However, the user should be aware of a number of issues before changing any of the defaults.  First, the Java Virtual Machine (JVM)  (see Java Control panel) must support any increased Image cache size setting.  Second, the computer running LookWMS must also support the increased cache setting.   Please ensure that you understand the effects on the Java runtime machine before changing any of the default cache settings.



The Automatically download high res data check box, if checked, will download data for the lens while the viewer is idle.  Turn this option off if you are struggling with a shortage of memory.

If the Display data as it's downloaded check box is checked, data will appear in the map window as it arrives.  If it is off, then data will appear in the map window only after all the requested data has arrived.

Edit Preferences — Network

Server connection and download times can be changed using the Network tab under the Edit Preferences dialog box.  If you connecting to the internet with a low bandwidth (slow) connection, then increasing these times may allow you to connect to a slower server.