Theodolite App for iOS is Breathtaking

| In-Depth Review

There are apps, and there are apps. Every once in a while, an app appears that’s so beautiful, so technical, and so completely exploits the Apple iDevice that it takes one’s breath away. This is one of those.

Theodolite from Hunter Research & Technology is an app that pulls together many of the iDevice’s capabilities in order to create the ultimate navigational tool for the outdoorsman. The display of, say, the iPhone becomes a viewfinder on which is overlaid GPS data (coordinates and elevation), compass heading, attitude and time data. You can e-mail the data to someone, and you can easily take a screen shot that captures all that data.


Here’s the full technical description from the author’s website: “Ability to take geo-stamped and geo-tagged photos and screenshots from the app, with 2X and 4X zoom, buffered background image saves, plus an option to write custom notes on photos. Integrated map with standard, satellite, and hybrid views, compass rose, and bearings. Ability to manage location markers on the map. Optical-mechanical gyro/accelerometer calibration. Zero angle reference mode. A-B survey calculator for height, distance, heading, position, and angles. Data logging. E-mail data export with KML. Clipboard integration. Percent Grade. Optical rangefinders. Mils. Night vision lens filters. MGRS, UTM, and four lat/lon formats.”

And it looks great too.


The app is available in several versions. There is Theodolite Free for the iPhone which has ads. You can buy the Theodolite Pro for the iPhone, which is ad free, for US$3.99. That’s a downright steal. And there’s a Theodolite HD for the iPad, which is identical and doesn’t suffer too much from the mediocre camera system in the iPad 2. This review is based on the Pro version, and I can confidently suggest that you can just skip the ad supported version and go right to the paid ones.

The app is compatible with any iPhone, the iPod touch (4G) or any iPad 2. Compass use requires iPhone 3GS, 4, or 4S. iPhone 4 or 4S, or iPod Touch 4 required for gyro and Retina Display support. the app requires at least iOS 4.1.

Practical Uses

The app is useful for a wide variety of outdoor activities, more than you may have thought of at first. The obvious ones are backcountry, skiing, fishing or boating navigation plus search and rescue. But the range finder can be used for golf. And other uses include surveying, landscaping, tracking the trajectory of objects, triangulating on wildfires, accident investigations, real estate and a lot more.



The app is nicely documented, both inside the app and on the author’s website. Each function is well explained, although, for the sake of form, and for newbies, it would be a plus to have a graphic documenting each of the items in the display with callouts.

The documentation includes a nice FAQ that covers some if the nuances of the app, interpreting the display, and trouble shooting.


I found the app to be a joy to use, especially after I diagnosed one peculiarity. Back in 2011, I turned off the Compass Calibration in my iPhone 4S when we all thought that might be the source of some unwanted battery drain. I don’t think that’s an issue anymore, but if you turned that off, you’ll have several symptoms. First, the iPhone’s Compass app cannot be set to true north, only magnetic north. Second, the azimuth display in Theodolite will be very, very wrong.

The way to fix this is: Settings -> Location Services -> scroll to Bottom -> System Services -> Compass Calibration -> On.

The author provided more details in an e-mail:

Roughly 3-4 people have contacted me about this problem. It had me scratching my head for a while, but some other developers on the Apple developer forums were reporting the same issue, and eventually we all got to the bottom of it. Given the small number of users this affects, it was a bit hard to work out. But in the end, an obscure and forgotten system setting change fits the pattern perfectly.

Long term, I will implement a change in the app and have it turn the compass indicator red when the GPS hardware isn’t reporting back a valid magnetic declination. Normally that condition would be lumped under the GPS position indicator going red, but with the new iOS 5 settings, it’s now possible to have good position data but invalid magnetic declination.”

I was particularly delighted to note that while images taken with the camera icon and saved to to the photo album contain EXIF data, images exported via the e-mail function do not. That way, you have better control, if necessary, of your privacy. Or not — when needed — for things like search and rescue. I verified that with a photo sent to myself and inspection with the Graphic Converter app that can reveal the EXIF data.

Having an astronomy background, I was particularly pleased with all the different formats available for position measure; D.X, DMS, UTM and others. And of course, distances can be viewed in meters for feet. There are some very nice options for determining how photos/screenshots are taken. Both these option pages provide evidence that the developer is very technical and addresses the needs of different kinds of users.


Camera/Photo/Screenshot Settings

The optical range finder depends on a single lens technique of using a reticle to estimate distance. That’s not quite as elegant as a dual lens, binocular technique, but that’s the best one can do with a single lens system. You have to roughly know the size of a distant object. Then angular data allows you to converts that to a distance. There is also a 2x and 4x digital zoom, so the app also can serve as a modest, low power monocular. There are some filter settings that can be set to, say, red to preserve your night vision or other colors to improve the usability in low light. (Not available in the free version.)


Range Finder

A particularly helpful function is the status display of the sensors and the estimated accuracy. Measurement without sanity checks and estimated accuracy is for amateurs, and this function is further evidence of the technical expertise of the developer.


Sensor status and accuracy estimates

All in all, I would say that given the variety of uses for this app, linked to above, just about any iPhone user would consider it a must-have. For four bucks, it’s a steal.


This app is similar in some ways to Spyglass, reviewed earlier. Spyglass is a sextant app that can also show the calculated position of the sun and moon. This app is a pure theodolite, but also can be used for some astronomy applications, such as finding angles.

I have a great fondness for apps that integrate all the sensors available in the iPhone and iPad. Apps like this bring out the best in those products. Not only does it make for a terrific technical tool, but it also makes you feel as if you’re Captain Kirk.

Product: Theodolite 2.6.1

Company: Hunter Research and Technology

List Price: US$3.99 (Pro and HD versions)



Goegeous display, integration of iPhone sensors, log and e-mail functions, great documentation, terrific price.


None noted.

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Wow! Thanks for the heads up and review.


Wow. I wish I had an iPhone now. Maybe this year…

Lee Dronick

I just downloaded it, looks to be great app!


This app is a pure theodolite, but also can be used…

OK, I’m not being a smarty-ass, but can this really be used as a theodolite?  Are we actually going to see civil engineers using their iPhones instead of their $5-10,000 theodolites?

If so, I’m impressed.

Lee Dronick

OK, I?m not being a smarty-ass, but can this really be used as a theodolite?? Are we actually going to see civil engineers using their iPhones instead of their $5-10,000 theodolites?

Probably not, but it would be interesting to see a comparison, because this app looks pretty sensitive.  The iPhone, or iPad would need to be on a tripod, I found it hard to stay on target. However, this could be an aid to help control ones breathing and stay on target.

The splash screen is classy, it looks like a label on a precision instrument box/case.


Probably not, but it would be interesting to see a comparison..

It certainly would.  This, from their web site gives me hope, however:
“Theodolite is used in the field by surveyors, geologists, architects, engineers, military personnel, competitive sportsmen, and search and rescue workers around the world. The app has been featured numerous times in iTunes, and has been the #1 selling Navigation app several times during 2009, 2010, and 2011.”

I found it hard to stay on target.

They have a camera stabilizer app that might help.

This is all very exciting.  Professional apps for professionals at under $5?  Yowwza!

Lee Dronick

iJack, this app and the iPhone are probably a lot more accurate than my lensatic compass and the contour maps that I still drag around. I am no longer in the navigation business as a profession, but the mindset will be with me until the family takes away my hiking boots. Anyway mount the iPhone on a camera tripod, monopod or even rested on a rock or something.

On the other hand if the power source for my magnetic compass runs out then we all are 2012.

I have tested the iPhone GPS and the satellite map view at prominent landmarks and I am very impressed with the accuracy.


Lee ~ When March rolls around, and the new iPad 3 is available, I am going to be purchasing my first ever iDevice.  I have to add, that except for pure lust, I have no idea why I am buying it, or even what I will use it for.  However, you can bet that this app will be an early download.

PS: Since we have swapped posts a few times, you can drop the “i” and just call me Jack.  wink

Lee Dronick

Lee ~ When March rolls around, and the new iPad 3 is available, I am going to be purchasing my first ever iDevice.? I have to add, that except for pure lust, I have no idea why I am buying it, or even what I will use it for.? However, you can bet that this app will be an early download.

The uses for it will appear. Among other things I am reading a lot of books on mine. Take it along instead of my MacBook Pro when I accompany my wife to the mall and sit at the food court instead of being bored while she shops. I have the Rhyme app and use it to work on my poetry. Use the iPad and the Pages app for creating outlines and copy. It isn’t a complete replacement for my MBP, but is a different sized screwdriver in the tool box.

PS: Since we have swapped posts a few times, you can drop the ?i? and just call me Jack.

Will do


The uses for it will appear.

Isn’t that funny, though?  We use to buy a tool because we had a perceived need. Now, it’s “that looks cool.  Bet I could find a use for it.”


Isn?t that funny, though?? We use to buy a tool because we had a perceived need. Now, it?s ?that looks cool.? Bet I could find a use for it.?

Actually, I think the best tools are kind of like that—you buy a tool for one purpose, and discover new uses as you use it, and it enables you to do things you never thought you could accomplish before. This app sounds like one of those. grin



Great app -  for serious stuff and amusement. Feeling like Captain Kirk I said to Siri:  “Beam me up, Scotty”.
Try it.

I too had difficulty holding the phone steady . I used a small bean bag to rest it on. The same bean bag I used to rest my Olympus Trip 35 on.


When I need an example of “don’t jump to conclusions” I’ll point to this App. I read the review and my reaction was “Oh great, another wonderful App that does magical things on an iPhone but on my iPod Touch will be so crippled as to be useless.” You see I’ve played with this kind of App before. Even bought a few and invariably though, they disappointed. But I figured what the heck I’ll try the free version.

Holy **** it’s great. It uses the motion sensors and gravity sensor very well. I don’t have GPS on my iDevices but Theodolite just makes do as best it can with what’s there and GoogleMaps. I love being able to email screen shots with all of the data in place. I love how it’s really accurate for A-B surveying. I find myself just shooting things across the room (I know that picture frame is 14” high, tap tap tap, wow it’s 16 feet away.) just for the heck of it. I agree with you, it’s great to see an App that will use the sensors that are available to their fullest and not whine about not being on a iPhone with GPS.

FWIW bought the Pro version and put it on both my iPod Touch and on my iPad where it works even better. Not sure, with the regular screen and mediocre camera what the benefit of the HD version would be for either of those. It will be spectacular though on the iPad3 with a Retina display.

Kurt Breede

I want to survey some land to generate a 3D topo surface. Will this app help me collect relatively accurate (+-1 m) point data?

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