How geospatial AI overlays the FMB sketch on satellite imagery and ground survey to quantify encroachment, overlap and extent shortfall before you buy Tamil Nadu land.
Tamil Nadu's cadastral surveys are old, and parcels have been subdivided, consolidated and fenced many times since the original measurement. The FMB sketch remains the legal definition of the boundary, but the ground accumulates drift: a fence a few metres into the neighbour's survey number, a road that ate a strip, an adjacent water body whose poramboke margin was quietly absorbed.
For a corporate buyer the consequences are concrete: buildable area smaller than priced, setbacks measured from the wrong line, or a portion of the compound wall standing on land you never bought.
The FMB sketch is digitised and georeferenced, scaled and anchored to known survey stones and reference points, then overlaid on current high-resolution satellite imagery and, where the transaction warrants, a licensed surveyor's total-station measurement. The three layers, legal, observed and measured, are reconciled and every divergence is quantified in metres.
Machine assistance matters because the comparison is geometric and repetitive: edge matching, area computation, encroachment polygons. The output is a drift map with each divergence graded, not an opinion that the site 'looks fine'.
Common findings on Chennai-belt industrial land: compound walls 1 to 3 metres over a boundary, an access road that crosses a third party's survey number with no registered easement, extent in the deed exceeding the FMB-computed area, and proximity to an odai or eri channel that triggers water-body buffer rules. Each is cheap to resolve before purchase and expensive after.
Where the parcel aggregates several survey numbers, the overlay also verifies that the numbers are actually contiguous and that no sliver of someone else's land sits inside the assembled block, a surprisingly frequent defect in older aggregations.
Geospatial checks complement the records read: the EC and deeds prove who owns the parcel, the overlay proves where the parcel is and how big it really is. Both feed the graded report, and material drift findings carry a recommended cure, joint measurement, rectification, easement registration or repricing of the shortfall.
On a site that will carry a plant or a data hall, we treat a verified boundary as a precondition to civil design, because every setback, firebreak and yard dimension downstream depends on it.
The Field Measurement Book sketch is the government's surveyed map of a parcel: its legal shape, dimensions and boundary. It overrides brochures and fences, so any purchase should verify the ground against the FMB.
By georeferencing the FMB over current satellite imagery and a ground survey, then quantifying every divergence in metres. Encroachments, overlaps and missing strips show up as measurable polygons.
Treat it as a finding to resolve before purchase: a joint measurement with the seller, a rectification deed where records are wrong, or repricing if the buildable extent is genuinely smaller.