The listerCompass is an advanced compass designed to allow a field geologist to take advantage of the iPhone's capabilities. Get it with iTunes http://www.apple.com/itunes/
Orient the compass where you want. Once it stabilizes, hit "Stop" or tap the screen. Double tap to record the data. Data is collected, averaged, and presented in a standard format (mean ± standard deviation). If the error is too large, then repeat the measurement. Data is provided relative to magnetic north - because you can always add the declination later.
If you want to measure a surface, put your iPhone anywhere on it.
If you want to measure the surface, and a lineation on that surface, orient the iPhone on the surface so that it is oriented with its long axis parallel to the lineation.
To measure both together place the iPhone on gthe surface, with its long edge parallel to the lineation. Upside down is also OK.
The mode most useful for surfaces is strike-dip-rake. Here: 1) strike is given as a single number such that the dip is to the right; 2) dip is the inclination of the surface plane of the compass, no matter what direction the compass is pointed; 3) rake is the (anticlockwise) angle of rotation that links the strike direction of the plane being measured, to a line on that plane. Rake is positive if the direction of rotation is anticlockwise from the strike.
The mode most useful for lines is yaw-pitch-roll. Here we use the convention set by aircraft: 1) yaw is the plunge direction, or trend, of the lineation; 2) pitch, or plunge, is the inclination of the line to the horizontal; 3) roll is the angle between the surface and a plane that includes the lineation, but strikes at right angles to it.
Points to note:
1) Move the compass to "trigger" measurement.
2) If the error is large, repeat the measurement. The phone must be held still until the error subsides.
3) Measuring beneath dark overhangs with the rock face at arm's length overhead is difficult with analogue compasses, but the listerCompass can be used with the iPhone upside down to measure the orientation of bedding, foliations and/or lineations. This has been tested but if you are using the iPhone in such situations and experience practical difficulty, please let me know.
4) Use the annotation feature to record information as you go along, e.g., if you are not measuring lineations just say so. Then if you begin to measure lineations (and not foliations) you can simply add an annotation to say "Now measuring lineations". Remember that the listerCompass can simultaneously record both foliation and lineation data with one measurement, thus reducing the amount of effort required on an outcrop.
Turn the GPS on/off in the Settings Panel.
The data string may be annotated with comments added as you measure different outcrops.
If you have saved a measurement once then before saving again you will need to "start measuring" (again).
To request improvements (or to report errors) Email clear_range (at) yless4u.com.au
Protect your iPhone. Field work is not likely to improve its looks. Practically speaking, at least to make the batteries last longer, I purchased a red http://www.mophie.com/ but also see http://reviews.cnet.com/.
Version 2 allows more flexibility as to how to use the compass. Double tap to change the mode. Touch a button, and then drag and exit the button area to freeze lock in (or to unlock) that setting.
Touch the "Information" button to see your data. Collected data is stored and can be edited and sent by Email as an ASCII file with XML tag, or as textTAB delimited data.
To avoid unnecessary bother, buttons must be double tapped before any action ensues.
The structural data collected can be analysed with a program called iGeologist.
The iGeologist program will contour data, and make plots, including seamless integration of data produced using the listerCompass. Report writing is as yet not included.
The compass also logs location if this is allowed. This data can be output with the compass measurements.
BEWARE - some electronic compasses available on iTunes do not always provide correct "heading" information. Test any compass app by tilting the iPhone to a steep orientation, or by slowly twisting it, or holding it upside down.
The listerCompass computes direction using primitive functions.