The set-up
Take a representative site. A 500,000-tonne coal yard at a thermal power plant or integrated steel plant. Realisable value per tonne: ₹6,000 (fully-loaded landed cost, not free-on-rail price). Closing-inventory cycle: monthly.
The variance gap
Manual surveying — rope-and-tape, profile-board, experienced eye — delivers volume estimates with a variance envelope of ±5% in typical industrial practice. Drone-photogrammetric measurement, reconciled against weighbridge throughput, delivers ±1.5%. The gap is 3.5 percentage points of inventory uncertainty.
On a 500,000-tonne base, 3.5% is 17,500 tonnes. At ₹6,000 per tonne, that is ₹10.5 crore of inventory uncertainty per measurement cycle.
What "uncertainty" means on the balance sheet
Three places it bites. Book-to-physical reconciliation — every month, finance has to explain why the physical count differs from the book. Wide variance forces larger write-downs or larger reversals; auditors discount both. Revenue recognition on inventory transfer — inter-company transfers at steel integrates use the inventory number as the transfer basis. A wide envelope compounds to artificial P&L volatility. Working capital efficiency — inventory that cannot be measured cannot be financed against. Tighter variance unlocks better working-capital terms.
The cost side
A monthly drone stockpile programme at a single yard costs in the range of ₹1–3 lakh per cycle, depending on complexity. Annualised: ₹12–36 lakh. Against ₹10.5 crore of variance that the programme closes, the ROI is not a marginal argument. It is an order-of-magnitude argument.
What killed the argument historically
Three things. Drone operators who could not produce audit-defensible outputs; CFOs rightly refused to replace one imperfect method with another unreviewable one. Regulatory friction around airspace clearance. Lack of weighbridge reconciliation in the delivery, which left CFOs no way to test the claim.
All three are now resolved in any reputable deployment. If your current stockpile auditor cannot show you a monthly weighbridge-reconciliation table, that is the test they fail.
The operational uplift, for free
The CFO argument is the headline. The operational argument comes for free. A monthly drone dataset gives the yard manager a coverage map (where is inventory accumulating), a change map (where has it moved), and a blending model (which pile goes to which boiler). None of that is available from rope-and-tape. None of that requires new software on their side — just the PDF and the viewer.
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