RTK for GIS Mapping: Collecting Field Data You Can Trust

GIS data is only as useful as the positions attached to it. A water valve recorded three metres from where it really sits can send a crew digging in the wrong place, and a habitat boundary that drifts between surveys makes change analysis meaningless. RTK brings field-collected GIS points, lines and polygons down to centimetre-level accuracy, so the map matches the ground.

Where accuracy matters in GIS

• Utility and asset mapping: valves, poles, manholes, meters and buried services that crews must find again.
• Municipal inventories: street furniture, trees, signage and road markings.
• Environmental and agricultural work: sample plots, field boundaries, drainage and erosion monitoring.
• As-built records: capturing what was actually installed on a construction or infrastructure project.

For a quick inventory, metre-level positions may be enough. For anything that will be dug up, re-measured or used as a legal or engineering record, RTK is worth the extra setup.

A typical RTK GIS workflow

• Pick a correction source: a government network, a commercial network, or your own base on a known point.
• Pair a multi-band GNSS receiver with a phone, tablet or rugged handheld running your field app.
• Connect to the correction stream over NTRIP using mobile data.
• Wait for a 'fixed' solution before recording, and let your app store the fix status and accuracy with each feature.
• Sync the data to your GIS platform, checking the coordinate system and height datum on import.

Coordinate systems: the most common mistake

Correction networks deliver positions in a specific reference frame, and your GIS project may use a different national or local one. A mismatch can shift every feature by a metre or more, even though the receiver reports centimetre accuracy. Confirm the frame your network uses, configure the matching transformation in your field app or GIS software, and test on a known control point before a large job.

Working in difficult environments

GIS work often happens where RTK struggles: under tree canopy, beside buildings or in narrow streets. Multi-constellation, multi-band receivers fix faster and hold the fix longer. Where a fix is impossible, record the point with an offset from open ground, or flag it as lower accuracy so it is not mistaken for survey-grade data later.

Quality control

• Store fix type, reported accuracy, satellite count and timestamp as attributes on every feature.
• Re-measure a known point at the start and end of each day.
• Set a rule in your field app to reject points that are not fixed, or to warn the user.
• Keep notes of the correction source and mount point used for each project.

Choosing a reliable correction service is the foundation of accurate GIS data. Browse the directory to find networks covering your area, and compare free government services with commercial options.