Imagine that we want to zoom in on something in a picture. We will call this the target. For example area 1, 2, 3 or 4 in the Knox Zoom Range Test below.

Knox Zoom Range Test

Knox Zoom Range Test Chart for Image Viewer Efficiency Testing

To zoom in with OrbitZoom you click down on the target and then click up. This puts you into zoom mode. You then move your cursor radially away from where you clicked. This represents the physical action of pulling the picture towards you. At any time, you can reduce your zoom by moving the cursor back towards the target. This represents pushing the picture away from you. The movement mirrors the physical world so is very intuitive.

The back and forth motion for zooming in and out allows for simple, uninterrupted control and does not require supplementary keys to be held down like a shift key to differentiate direction.

There is a zoom technique where you zoom in and out by moving your mouse up and down. This has an advantage of being able to zoom out right away. But most of the time we are interested in zooming in so this advantage is slight. There is a major disadvantage in using up and down for zooming in and out because there are contradictory expectations:

A. Zooming in is what we want to do so it is positive as is moving up.
B. Moving up is pushing the mouse away from you so that would zoom out.

These above contradictory expectations make it impossible to provide an intuitive interface with up and down mouse movement for zooming in and out. With a radial interface you click and no matter which way you move you zoom in. So there is no question. You move the opposite way to zoom out.

The freedom to move in any direction to zoom reduces strain from repetition. Another way the OrbitZoom interface reduces strain is that you click up to enter zoom mode. This means that you do not have to hold the mouse down as you zoom which reduces strain on your hand, wrist and arm.

Clicking up to enter zoom mode also means that pan mode is available by clicking down and dragging the picture. You click up to stop dragging. Zoom and pan is accomplished with just the single traditional left mouse click without any other keys.

With OrbitZoom you click then zoom then click to leave zoom mode. This is the completion of a zoom stage. You can then pan or you can click to enter another zoom stage to refine your target. You can pass through as many zoom stages as desired but you will lose your ability to zoom out farther than your latest zoom stage. At this point, we provide a double click interface to zoom back out to fit. Ninety percent of the time, we will want to zoom out to fit.

Moving your mouse to zoom out from a picture that is zoomed way in is disorienting because you can’t see where you are going. And it can take a long time. A quick double click to zoom all the way out is much easier and faster and prevents disorientation. Even if you then have to zoom back in to a target, it is still easier and faster to zoom right out, see your target and zoom in.

Knox Zoom Speed Test Chart

Knox Zoom Speed Test Chart for Image Viewer Efficiency Testing

We have tested with the Knox Zoom Speed Test Chart and the Knox Zoom Range Test Chart to test picture viewer efficiency and fall at 10 seconds for each test. 10 seconds is the rating for an excellent image viewer. The first test measures the time to move through five circles dispersed around a 5000 x 5000 image and each having a small instruction as to which circle to go to next. OrbitZoom works well because you can quickly Zoom in on a circle, read the instruction, double click to zoom out and get your bearings then zoom in on the instructed circle, The second test measures how quickly you can zoom in to four differently sized rectangles with random positions.

To give you an idea, the Windows Picture and Fax Viewer scored 25 seconds and 30 seconds respectively.

You are welcome to comment if you have any questions or suggestions,




  1. […] Theory Posted by: orbitzoom | Jan 27, 08 […]

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