HyperLens

Layers and Lenses

Layers and Lenses show different views on an image. Fundamentally, they are similar to the layers offered by most Image Processing, GIS, or other visualisation programs. But the lenses can not only be turned on and off, but can be interactively moved, resized, re-ordered, or even made partially or wholly transparent by the user, bringing a new level of interactivity to the viewing experience.

Every lens is identified by its colour, and has:

• An on/off button - lit when turned on - in the control panel left of the display.
• A wire frame outline, in the lenses own colour.
• Control tabs: top left (to drag the lens) and bottom right (to resize it).
• Other attributes and possibly controls defined by the lens itself.

Beyond that, nothing is fixed. A lens may be just a viewer, or an interactive editor with its own controls (visible when the lens is active). It may be a filter on the underlying image, a different image, or object data. It can define its own actions: for example, WWW hyperlinks, or offer the facility to reproject an image. Since the Extension Framework makes it easy to define your own lenses, there is literally no limit to what they can be used for.

A Layer differs from a Lens in HyperLens only in that it is not loaded immediately when the project is loaded, but is instead added to the Layers Menu. Whenever the user selects a Layer from the menu, its corresponding lens is loaded and added to the control panel. Layers are well-suited to:

• Any lens that loads substantial data over the Internet. Making it a Layer speeds startup by delaying loading until it is requested by the user.
• Views that are of secondary importance in projects having large numbers of lenses. Or views that are complex, and might confuse a novice user.
• Public (e.g. Internet) contributions to an 'open' project that accepts such contributions but limits the addition of default lenses to authorised core team members.

(put some examples here)