NOTE: this tutorial is currently seriously out of date
This mini-tutorial will guide you through the basics of HyperLens. Lesson one deals with using the viewer to browse HyperLens projects, on the Internet or on your local machine.
HyperLens can run either as an Applet (a JAVA program launched from a web page) or as a standalone program in its own right. There are some slight differences, which depend on how you are running it. We have marked these: if your Web browser supports CSS stylesheets you will see:
Text marked like this describes Applet behaviour. If you are running HyperLens as standalone, don't expect it to work as described.
Text marked like this describes Standalone behaviour. If you are running HyperLens as an applet, don't expect it to work like this.
If you just reached this page through HyperLens's Help menu, you will want to skip this step. Otherwise you can:
Run HyperLens as an Applet from this server. You will need a Web browser supporting JAVA 1.1: if you're not sure whether yours does or not, please see the browser notes on the Applet page.
Download a HyperLens Viewer and run it as standalone. This requires you to have a JAVA runtime, such as Sun's java or jre (available free) installed on your computer. You can then launch HyperLens using the command:
jre -cp HyperLens.jar HyperLensViewer data/front
A Project in HyperLens comprises one or more image, together with associated data - such as image processing filters or annotation - presented in lenses. A project is specified in a Project Definition File, which is a simple text format.
Use the File Menu to open a project. Select Open, and select the first of the preloaded examples.
You are now viewing a satellite image of the Cote d'Azur, on France's mediterranean coast. We will use HyperLens to explore some interesting points in this image.
This image is from the Sea and Space project, where there is a webpage describing it in detail. The project definition file tells HyperLens to load this page into your web browser when you open the project. If you are running HyperLens standalone this will not work: instead you get a popup window advising you to open the webpage. You can find the page in question here. Use the "OK" button to dismiss the popup.
Move the mouse around over the main display. Watch as HyperLens displays your position. Hold a mouse button and drag: note the extra detail displayed.
This is a geographic image, so the display is of latitude/longitude and distance in Km. With a different image type we might use different measures, such as pixel positions within the image.
The red, green and blue lenses are filters on the image, each showing the intensity of one band within the image (as greyscale).
Use the buttons to the left of the main display to open a lens. The buttons are on/off toggles: note how they light up when their lens is activated.
Pick up any lens, using the mouse on the tab in the top-left corner of the lens. Note that you can drag it to anywhere you please on the image.
Try the tab at the bottom-right of a lens. This permits you to resize the lens.
Repeat the above until you're comfortable with the lens controls. Make sure you try it with more than one lens displayed: note how selecting a lens brings it to the front.
Tip: if you ever can't find a lens, use its button to toggle it off and then on again. This will bring it to the front.
Don't worry - we don't expect you to be expert in remote sensing. The Sea and Space introduction gives you the necessary background.
Open the first lens (labelled "intro"), and expand it to fill most of the display. You will see a couple of interesting features are labelled in this lens. Click on the "oil slick" and "weather front" labels to see the explanations of interesting features visible in this image.
These labels link to popup windows. Hyperlinks to a webpage or to another HyperLens project are also supported. We will return to these when we look at the HyperLens Editor.
A "Layer" in HyperLens is a generalisation of a Lens. It is not automatically loaded when you open a project, and may be dynamic: for example, a layer may comprise the results of a database query. However, after loading, a layer instals itself as a Lens.
The project we are viewing has a single layer called map, which is a scanned image of a map of the area of coastline we are looking at. It is not installed immediately because it is a large image file, and may take some time to download over a slow Internet link. It is downloaded only on demand.
Download the Map layer, from the Layers menu. When it is installed, open the Map lens over the area of coastline affected by the oil slick.
The map at this scale is unreadable.
Use the Scale control above the image to zoom in to a factor of about 2-3. You will find the area of interest moves outside the visible display: either use the scrollbars or (if your screen is big enough) expand the HyperLens window to see the map section. Now you can see where we are!
Warning: if memory is tight, zooming to a large scale can be very slow.
Position the Blue lens over the slick, and bring it on top of the map display.
Images used in this example are Copyright © the European Space Agency.
From the File menu, select Open URL and enter the URL http://www.webthing.com/software/hyperlens/ex3
This will load another example - a different kind of satellite image, together with a webpage describing the image. This image provides an accurate measure of terrain movement, over the active volcano Etna (Sicily).
Each band (colour) in this image shows something different:
Use the colour lenses to explore the three bands.
ESA also supply an Interferometric Browse Product (IBP) (please see their webpages for details). This is available as a Layer in our HyperLens example.
Load the IBP Layer, and open its Lens. Position the lens where it covers the volcanic cone, and observe the 'interference patterns'.
The bands in the IBP are strikingly coloured, and can be viewed on top of the original image.
Line up the Red lens with the IBP, leaving the IBP on top. Now adjust the 'transparency' control to about 70%.
Now you can see fringes superimposed on the coherence layer (and consider how much easier that was than constructing a similar image using [insert your favourite software here] would have been).
Turn off the Red lens. The view of the fringes on the colour image may be of less scientific value, but is visually appealing! Try also the fringes on the Green lens.
Load the IVBP Layer. Open the lens, and position it over the cone. Watch Etna brought to life!
The IVBP is the same image as the IBP, so HyperLens has already downloaded it, and you won't have to wait.
The code to produce this animation lens took less than an hour to program using the HyperLens API, and - as with any other lens - can now be applied to any other image to which it is appropriate.
Now it's time to explore HyperLens for yourself. Use the New or any of the Open options from the File menu to load an image of your choice.
Note that, if you are running HyperLens as an applet, JAVA security will prevent you accessing files on your own hard disc, and will restrict certain other operations.
HyperLens Editor tutorial to follow.