When designing Terrapad, we've tried to design an interface which was non-intrusive and, at the same time, intuitive.
However, Terrapad is a complex application. Much more so than most apps on the app store. The sheer number of possible actions or functions prevents us from using a static (or fixed) interface. We chose to present to the user a dynamic interface, dependent on a number of factors:
1) The presence or absence of user data (geotags or geozones) at a given point on the map 2) The previous operation or selection 3) Previously entered data in the database (favorite geozones or geotags)
We've come up with the wheel menu that you've been seeing when using the application. Each zone on the wheel holds an icon which represents an action. You can learn what each action does by holding your finger over the zone.
The wheel has numerous benefits: - It is only displayed when needed (a single tap on the map) - It can hold a large number of actions (since the zones of the wheel are resized dynamically) - It does not obscure the tap-point on the map (and is also centered on it), letting you see the area of interest - It helps the user place data on the map precisely by superimposing crosshairs over the center area
The wheel can be moved around by dragging the 'hollow' center portion.
The map can be interacted with by dragging outside the wheel even when the wheel is on-screen.
However, there are trade-offs to this user interface paradigm. It is seldom-used in iPhone applications and may be unfamiliar to a user
If you have ideas on how we can improve Terrapad's user interface, do not hesitate to post.
I like the wheel a lot, however one draw back is that when performing mensuration you cannot see thru your finger at the point you are trying to center on.
Indeed, placing your finger inside the wheel's center to move it makes it difficult to center it precisely on the desired location, whether you are using the tape measure tool, or attempting to place a new feature.
One way that may help centering the wheel with more precision is to move the map instead of the wheel - while the wheel is being shown, you can still pan and zoom normally provided you place your fingers on the map, outside of the wheel's boundaries.