Delhi's War on Duplicate Images: How the Capital Stacks Up Against Mumbai, London and Seoul

Delhi's three municipal corporations, unified under the MCD in 2022, are sitting on an estimated backlog of digitised property records, heritage documentation files and urban planning maps in which duplicate and mismatched images account for a significant share of stored data—slowing down everything from building permit approvals in Rohini to heritage conservation surveys in Shahjahanabad. The problem is not cosmetic. It is costing time and money that Delhi's civic machinery can ill afford.

The push to address duplicate image data in public records has gathered pace globally over the past eighteen months, driven by the expansion of AI-assisted city management tools and the pressure on urban governments to make spatial data interoperable. Cities that lag risk wasted procurement spending and, more practically, planning decisions built on contradictory visual records. In Delhi, where the Delhi Development Authority and the MCD often maintain parallel datasets covering the same neighbourhoods, the duplication problem runs structurally deep.

What Delhi Is Actually Doing

The DDA launched its GIS-based Master Plan data portal in phases beginning in 2023, intending to consolidate aerial imagery, satellite snapshots and ground-level photographic documentation into a single queryable system. The portal covers the city's 11 planning zones. However, officers working on the Phase 4 Delhi Metro corridor alignment—particularly the section threading through Janakpuri West and R.K. Ashram Marg—have flagged that conflicting imagery sets from different survey years are generating inconsistencies in land-use classification records. No official figure has been published for how many files are affected, but the issue has been acknowledged in DDA board meeting summaries circulated to planning consultants.

The National Informatics Centre, which maintains data infrastructure for multiple Delhi government departments from its headquarters on CGO Complex, Lodhi Road, has piloted a deduplication algorithm on property tax photograph uploads since January 2026. The pilot covers ward offices in Central Delhi. The MCD's own communications about the pilot describe it as an effort to reduce redundant storage load on department servers—a practical, if unglamorous, administrative reform.

Chandni Chowk presents the acutest version of the problem. The Old Delhi streetscape has been photographed by at least four separate agencies—the Archaeological Survey of India, the NMMC heritage cell, the Smart Cities Mission's Delhi component, and private consultants hired under the Chandni Chowk Redevelopment Project—producing overlapping visual archives with no common metadata standard. Cross-referencing those archives for any new development application currently requires manual reconciliation.

How Other Cities Compare

Seoul's Smart City division began mandatory image deduplication across its public data repositories in 2022, using hash-matching software across a centralised urban data lake administered by the Seoul Digital Foundation. The city reported a 34 percent reduction in redundant spatial image files within 18 months, according to figures published by the Seoul Digital Foundation in its 2024 annual review. London's Ordnance Survey partnership with the Greater London Authority consolidated aerial photography datasets across 33 boroughs by 2023, establishing a shared API that borough planners must use before commissioning new surveys—preventing fresh duplication at source rather than cleaning it up after the fact.

Mumbai offers the closest structural parallel to Delhi. The Brihanmumbai Municipal Corporation and MMRDA have historically maintained competing datasets for the same Development Plan zones, particularly around the Eastern Freeway corridor and Dharavi redevelopment area. Mumbai has moved faster on metadata standardisation since 2024, partly because the Maharashtra government tied deduplication compliance to eligibility for central Smart Cities Mission funding tranches.

Delhi has no equivalent financial incentive mechanism in place. The Smart Cities Mission funding cycle for Delhi's designated areas—including the South Delhi component centred on Sarojini Nagar—does not currently include explicit deduplication benchmarks in its reporting requirements.

What changes that calculus is pressure from above or below. Internationally, the pressure came from interoperability mandates tied to digital public infrastructure funding. In Delhi, the more immediate lever may be the Metro Phase 4 land acquisition timeline: inaccurate or contradictory property imagery has already contributed to delays in compensation hearings along the Aerocity-Tughlaqabad corridor, and DMRC project officers have a direct institutional interest in clean data. The NIC pilot in Central Delhi is scheduled for evaluation in October 2026. If it demonstrates measurable efficiency gains, planners say an expansion to South and East Delhi wards is the logical next step—though formal decisions will depend on MCD budget allocations in the next financial cycle.