Field Survey Companion
The geologist’s field notebook on the phone: stations, measurements, samples and photos, even without a connection.
Records a field traverse station by station: an averaged GPS position, lithology, formation and description, bedding, joints, faults, foliation, veins and lineations typed or read from the phone held on the rock and corrected to true north, numbered samples and photos kept on the device. It works without a connection after the first visit, and when the connection returns every station is completed with its place name, ground elevation and mapped geological unit. It draws the station map, a traverse plan to scale with strike-and-dip symbols and a stereonet of all measurements, builds a photo sheet and a PDF field report, exports CSV, GeoJSON and KML, and sends the measurements to the Stereonet Lab and any station to the Site Report.
Overview
Field work is where geological data begins, and where it is most often lost: notebooks get wet, photos are separated from their stations, and measurements are typed again weeks later. The companion keeps everything together from the outcrop to the report, on the phone the geologist already carries.
It is the link between the Shandal tools: measurements go to the Stereonet Lab for sets and kinematic checks, stations go to the Site Report, and the exported files open in any GIS.
What you enter · What you get
What you enter
- Averaged GPS position or typed coordinates
- Lithology, formation and description
- Planar and linear measurements, typed or read from the phone
- Samples and photos
What you get
- Station map and traverse plan with strike-and-dip symbols
- Stereonet of all measurements
- Photo sheet and PDF field report
- CSV, GeoJSON, KML and a full backup with photos
How it works in the field
Method and equations
Position
Satellite fixes are collected for up to 20 s and averaged with weights 1/σ², keeping the readings within 1.6 times the best accuracy.
Phone compass-clinometer
The normal of the phone back is computed from the device orientation angles; the last 30 readings are combined by the Fisher mean with their 95 % cone, and the dip direction is corrected to true north with the IGRF-14 declination at the station.
Figures
Traverse plan in local UTM metres with strike lines and dip ticks; stereonet on the lower hemisphere, equal-area projection, planes as great circles with their poles and lines as triangles.
Accuracy and error limits
- Phone GPS gives ±3–10 m in the open after averaging, worse in valleys, beside cliffs and under trees; heights are ±10–20 m. Phone compass readings are typically ±2–5° in dip direction and ±1–2° in dip after calibration, and the 95 % cone shown with each reading tells how stable it was.
- Magnets, steel tools, vehicles and power lines deflect the phone compass by tens of degrees; rough surfaces give the attitude of the patch under the phone, not of the whole plane. Map data added online are regional (elevation ±5–10 m, unit boundaries ±0.1–1 km).
- To reduce the error: calibrate the compass by moving the phone in a figure of eight, check it against a geological compass at the start of each day, place a clipboard on rough surfaces, keep metal away, take several readings per plane, and download a backup at the end of every field day.
Who uses it
Standards and references
- Fisher, R.A. (1953). Dispersion on a sphere. Proceedings of the Royal Society of London A, 217, 295–305.
- Alken, P. et al. (2021). International Geomagnetic Reference Field: the thirteenth generation. Earth, Planets and Space, 73, 49; IGRF-14 coefficients (2024).
- Allmendinger, R.W., Siron, C.R. & Scott, C.P. (2017). Structural data collection with mobile devices: accuracy, redundancy, and best practices. Journal of Structural Geology, 102, 98–112.
- Novakova, L. & Pavlis, T.L. (2017). Assessment of the precision of smart phones and tablets for measurement of planar orientations. Journal of Structural Geology, 97, 93–103.
- Coe, A.L. (ed.) (2010). Geological Field Techniques. Wiley-Blackwell.
At a glance
- Category
- Field geology
- Runs on
- Phone, tablet and desktop browser
- Export
- Traverse plan and stereonet as PNG, JPG and PDF; PDF field report with photo sheet; CSV, GeoJSON, KML; full JSON backup with photos
- Access
- Free
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