Datumark: Survey Camera

Datumark turns your iPhone into a precise field-survey instrument. Capture coordinate-stamped photos, measure distances and areas on site, convert between coordinate systems, and export clean data files — entirely on device. No account. No cloud. No tracking. Your position data never leaves your phone.

Built for surveyors, construction and utility crews, field researchers, inspectors, geocachers and anyone who needs trustworthy position data where there is no signal.

GPS FIELD CAMERA
• Burn coordinates, bearing, altitude, datum and magnetic declination directly into each photo
• Choose the coordinate readout: latitude/longitude, UTM or MGRS
• Writes standard EXIF GPS geotags into every image
• On a device without a usable camera it still records a clean coordinate field card, so nothing is lost

COORDINATE CONVERTER
• Convert any position across latitude/longitude, UTM and MGRS
• Switch geodetic datums — WGS 84, NAD 83, NAD 27, ED50, OSGB 1936, Tokyo, Pulkovo 1942 — with full 7-parameter Helmert transforms
• Degrees / minutes / seconds, degrees-minutes, or decimal degrees
• Grid convergence and point-scale factor for every location
• Enter coordinates by hand or read your live GPS fix

ON-SITE MEASUREMENT
• Distance along a path and enclosed area, computed on the reference ellipsoid (Vincenty geodesics)
• Metric or imperial: metres, kilometres, feet, miles, hectares, acres
• Log waypoints and record tracks in the field

MAGNETIC DECLINATION & ELEVATION
• Full World Magnetic Model (WMM2025) computed on device — declination, inclination and field strength for any point and date
• EGM96 geoid model converts GPS ellipsoidal height to orthometric (mean-sea-level) elevation

OFFLINE VECTOR BASEMAP
• A worldwide vector basemap — coastlines, country and state borders, rivers, lakes, roads and thousands of populated places — renders directly on device
• Pan and zoom smoothly with no tiles to download and nothing fetched from a server

CLEAN EXPORTS
• Export waypoints, tracks and measurements as GPX, KML, GeoJSON or CSV
• Share anywhere with the standard share sheet — files are generated on your device

BUNDLED REFERENCE DATA (all included, all offline)
• World Magnetic Model 2025 coefficients (NOAA / NGA / BGS, public domain)
• EGM96 geoid-undulation grid (public domain)
• Datum transformation parameters
• A worldwide Natural Earth vector basemap (public domain)

PRIVATE BY DESIGN
Datumark works in airplane mode, in a dead-zone canyon, offshore, or underground. Everything is computed on your device from bundled reference data. There is no login, no tracking, and no server — your locations, photos and field notes stay with you.

Take it into the field.