Hi Andrea,
Some good points there and in Richard's email as well. Many thanks.
In FieldMove Clino you can manually enter your measured data if you do not "trust" the reading from your phone. We can certainly look into the speech recognition function for this as well - we were talking about this yesterday. If you have connectivity at the moment then you can use Siri in the notebook instead of typing. It seems to work well - better than some humans. I had a friend at university who asked his sister to help type up his thesis - the files came back with Greenshed fairies instead of Greenschist facies!
Basically most things are possible, but we just need to find a way to pay for the development costs. There's not really a big enough commercial market in the geoscience community for a digital mapping application. We rely on sales of Move to help fund the work that we do for the academic community.
Coming back to the wide range of compass readings that some people have observed on their devices. It's very important to reset the magnetic declination each day. It is calculated automatically in the Clino app, but you should manually turn this off and on at the start of each day as part of the calibration process. You might have to repeat this process a few times until things settle down.
The conversations that we are having at the moment are what we might expect to see when any new technology is introduced, but I suspect we won't be discussing the same issues in few years time - we'll just be talking about something else.
Best regards
Roddy
Roddy Muir
Managing Director
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-----Original Message-----
From: Tectonics & structural geology discussion list [mailto:[log in to unmask]] On Behalf Of Andrea Bistacchi
Sent: 28 August 2014 10:00
To: [log in to unmask]
Subject: Re: Suitability of iphones as digital compass-clinos -- scary observations
Hi, following up on Richard's comment, and recalling a similar thread a few months ago...
- a traditional compass is built around a permanent magnet that aligns to the earth magnetic field without any need for calibration. the body of a traditional compass is built with non-magnetic material and does not influence the reading (don't measure close to your hammer or phone!).
- a smartphone is equipped with a three-axis magnetometer which must be calibrated from time to time, and (1) it is difficult to say if the calibration is successful, (2) many android devices do not have a calibration app (mine - a sony - has got a hidden calibration utility that can be accessed with a strange hacker code).
- a smartphone is composed of a lot of magnetic parts: battery, electronic components and radio antennas! this means that the magnetic field around your three-axis magnetometer is given by the earth magnetic field PLUS the phone magnetic field. the latter varies according to the phone activity (e.g. sending a call). in a high-end electronic compass most of these problems are solved because non-magnetic material is used where possible, and the rest is very stable and calibrated (e.g. there are no antennas around).
So, as said a few months ago:
- test your phone against a traditional compass.
- turn off antennas, using "airplane mode".
- DO A SIMPLE TEST: place your phone on a flat surface, one side aligned with a reference line, and read the bearing = B. turn the phone around the vertical axis at 90°, 180°, 270°, aligning the other sides with the reference line. the bearing should be exactly B+90, B+180, B+270.
however on most phones there is a systematic error of 10-20° in some of these positions. this error is reduced but not totally eliminated in airplane mode... this gives you a rough estimate of the errors you can experience even when the phone is correctly calibrated.
Finally my personal opinion is that using a smartphone as a compass might be (still) questionable (I totally agree with Richard), and I always warn students on this, but on the other hand apps like FieldClino etc. are great because they allow to PLOT and ANALYSE data in the field.
so it would be great to be able to collect the data with a traditional compass and quickly transfer the data on the phone... a suggestion for Roddy and other software developers: would it be possible to "dictate"
measurements to the phone using the speech recognition function that is already built in in most operating systems? this would be very useful also when measuring in nasty places...
Best,
andrea
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