TapeMeasure
DESCRIPTION
TapeMeasure gives you the ability to take measurements from a previous position to your current position. It displays the latitude, longitude, altitude, and accuracy of your current position, as well as shows you the current measurement being taken. Measurement information includes the distance, height, and direction (heading) of the current position from the previous position. This information can be displayed in either feet/miles or meters.
Once you find a position with enough desired accuracy, you can start a measurement, exit the application, and continue the measurement later. This feature is useful for saving power when GPS is enabled. You can pause measurement updates and then either resume measuring from the same start point, or reset your measurement and start again whenever you desire.
The iPhone 3G will provide greatest accuracy for TapeMeasure because of its powerful GPS feature, but TapeMeasure will still work well for long distances with the original iPhone. Note that only the iPhone 3G can provide altitude information, and only with a good GPS signal. TapeMeasure will also work with the iPod touch, provided that different WiFi connections are active when starting and ending a measurement. Note that not all WiFi access points can produce location information.
FAQ
Q: Why can't I get my location on my iPod touch?
A: The iPod touch only has access to WiFi signals, and not all WiFi signals are mapped, so you won't always get
a position. TapeMeasure uses the same location information that is available in the standard Google Maps app, so
if you can't find your current position there, you won't be able to find it with TapeMeasure either. For more information
about using WiFi to find your location, see Skyhook's website.
Q: What kind of accuracy can I expect? Can I use this to measure, say, the length of a couch?
A: The software makes use of Apple's standard location services interface, and so you are limited by the
accuracy of your device. If you have the iPhone 3G, you will have the ability
to get much greater accuracy due to the GPS feature than the triangulation algorithm alone, which is only what is
found in the original iPhone. iPod touch users can only expect to get their position when connected to an
available WiFi network. Due to varying conditions, location information may be delayed, unattainable, or
inaccurate, so this should never be used as a true positioning device. You probably won't be able to measure anything like a couch with any degree of accuracy, unless you've got
a great (and we mean GREAT) GPS signal, and your couch is 30 feet long.
Q: Can I use this in the mountains where there are no cell towers or WiFi connections?
A: Yes. We tested this scenario by first removing the SIM card (along with WiFi disabled), indoors, and verified that we couldn't get a position, which shows that the phone is no longer using the cell towers without the SIM card.
Then as we walked outside, after a minute or so, positioning information began showing up as the GPS signal was acquired. We weren't able to test in a true "dead spot", but that's the best we could do in our location.
One thing we noted was that airplane mode seems to disable GPS (along with cell/wifi), so no position is found.
We understand why airplane mode would disable transmissions, but we're not not sure why it would disable a receive only function. If you want Apple to change their implementation (like giving a separate GPS enable/disable control), let them know through their support area of their website.
Q: Why does the Altitude/Height only display "N/A"?
A: Only the iPhone 3G can (but not necessarily always) deliver your altitude information. This information
will only be displayed when possible.
Q: Why does the Altitude/Height suck?
A: That depends on a couple of things. First, you must have a great GPS signal to have the possibility of getting decent altitude data. Second, most
handheld GPS devices use WAAS or barometric pressure sensors to assist with accuracy.
Garmin has a nice explanation here. We don't know whether iPhone 3G
uses either of these or not, but from our field tests so far the altitude data has varied between mildly accurate to completely inaccurate.
Our field tests obviously are not conclusive, nor are they meant to slander the overall performance of the iPhone 3G. What we have
seen is that compared to a standalone GPS unit with WAAS disabled, given 10+ minutes in a wide and unobstructed view of the sky, we have seen altitide discrepancies of 50% or even more. So,
treat the altitude measurements as very general, and expect that it will not be very accurate. This has nothing to do with the design of this
application, this has to do with the current limitations of the device.
Q: The resume function seems to reset the starting point. What's up with that?
A: Sorry about that... that bug is fixed in the next release, which should be available shortly. If you spot any
other bugs, please let us know immediately.
Q: I wasted 99 cents on this thing. It doesn't do anything except measure distances!
A: That's what it was made to do. It's very limited in scope, and as you can see, it doesn't have any flashy graphics.
Actually, we would love feedback as to what kinds of features you'd like to see in future revisions. We made this application
to measure distances because we thought it was a useful function that the iPhone is currently missing. There are plenty of
apps to tell you where you are, what trendy coffee shop is near you, how to stalk and/or be stalked by your friends, etc. This
will not become another social networking app. This is a utility. If you have suggestions for future enhancements, or any constructive
(or even destructive) criticism, get in touch. Not to state the obvious, but remember that you can't send us an idea, have us implement it, and then try to claim that
we ripped you off. If you send it to us, we have the right to implement it. If you have a really good idea and you want credit for it, we encourage you to use the very generous and comprehensive
resources that Apple has to offer, and try your hand at making your own application!