GPS Mapping
Field Mapping measures a field by GPS while you walk its boundary. Start at a corner, walk the edge, and the area is calculated from the path.
It is for fields that cannot be measured any other way — irregular boundaries, sloping ground, plots whose corners are not visible from each other, and land nobody has a document for.
It runs on free map tiles rather than a commercial mapping service, which is why it costs nothing to use and needs no mapping account. That was a deliberate change: the app previously loaded a paid maps SDK on every single page view for the sake of this one screen, which a farmer on a village connection paid for in seconds of loading time.
It is honest about GPS. Accuracy falls under tree cover, beside walls and buildings, and in bad weather — and a phone will still report a confident-looking number. The guidance is to walk it twice if the figure is going to be used for money, and compare.
The result saves alongside manually measured fields, so a farm can be mapped however each plot is easiest and still add up to one set of numbers.
What it is. The real area and perimeter of a field, from its actual boundary: draw it on satellite imagery or walk the edge with the phone's GPS, and get the area computed from the boundary points rather than from a shape fitted over them.
When to open it. For any field that is not a neat rectangle, which is most fields. Also whenever an area figure is going to be used for something that matters — a lease, a subsidy claim, an input order, an insurance value.
Have ready.
Step by step.
What it will not do. It measures the boundary you give it. It is not a cadastral survey, does not establish a legal boundary, and cannot resolve a dispute — where a revenue record or a licensed survey disagrees with it, they are the authority. Satellite imagery may be out of date and phone GPS is accurate to metres rather than centimetres.
An irregular four-sided plot with one curved edge along a watercourse.
What goes in:
What comes out:
Fitting a rectangle to this plot in Field Geometry would have been quicker and would have been wrong, and the difference is not small — a curved edge taken as a straight one commonly costs several percent of the area, which is several percent of every input bought against it, every season.
Open Field Mapping, find the field on the satellite map, and either tap the corners in order around the boundary or walk the edge with GPS recording. The area comes back in square metres, acres, hectares, square feet, square yards, bigha, kanal and marla, along with the perimeter.
A handful of metres per point, which on a large field is a fraction of a percent and on a small plot can be several percent. Walking the boundary twice and comparing is a good check. For anything legal, a licensed survey is what is needed — this is a working measurement, not a cadastral one.
Draw it where the boundary is clearly visible from above — a bund, a fence, a treeline — because it is far faster. Walk it where the edge is hidden under canopy, where the imagery looks out of date, or where the figure is going into an agreement.
Several ordinary reasons: the record may describe a different boundary, may predate a division or a road, or may itself be approximate. Where they disagree, the record is the legal authority. This tells you what the ground currently measures, which is a genuinely useful and separate thing to know.
Field Geometry computes area from dimensions you measure for a regular shape — a rectangle, a triangle, a circle. This computes it from the real boundary of an irregular field. If your plot is not a clean shape, this will be closer to the truth than any shape fitted over it.
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