Theodolite Free

Based on a centuries-old astronomical instrument, Theodolite Free is a cool multi-function augmented reality app for the iPhone that serves as a compass, GPS, zoom scope, and two-axis inclinometer. Theodolite Free overlays real time information about position, altitude, bearing, and horizontal/vertical inclination on the iPhone’s live camera image, like an electronic viewfinder. Uses are endless, from land surveying to navigation, and the app is great for hiking, boating, hunting, golf, sports, sightseeing, and finding your way around.

Be sure to check out the more powerful Theodolite Basic and Theodolite Pro apps. Theodolite Basic lets you take geo-tagged camera images and screenshots directly from the app, with 2X and 4X digital zoom options. You can choose to stamp geographical data and custom notes directly on the saved image for later reference. View your current position on the built in map view, with standard, satellite, and hybrid modes. On an iPhone 3GS and 4, bearing is updated live on the map with both fixed view and world rotation. Theodolite Basic also has optical accelerometer/gyro calibration. The app is $1.99 on iTunes.

Theodolite Pro includes all "Basic" features, and adds a zero reference mode for angles and a handy "A-B" calculator to compute height of landmarks, distance to landmarks, triangulate position, compute distance/heading between points, show relative angles between observations, and show points on the map. Theodolite Pro also provides integration with the system-wide clipboard, e-mail data export with KML, mil compass readout, optical rangefinders (including a mil-based reticle), night vision lens filters, display of percent grade, and multiple position formats including MGRS and UTM. Theodolite Pro is $3.99 on iTunes, and was the #1 selling US navigation app in December 2009 and September 2010.

Theodolite works on any iPhone and the 4th generation iPod Touch. GPS functionality requires an iPhone 3G, 3GS, or 4. Compass functionality requires an iPhone 3GS or 4. On iPhone 4 and iPod 4, data are augmented by the gyro, and the app uses high res artwork for the Retina Display.