Istanbul's Duplicate Image Problem: The Key Decisions That Will Shape the City's Digital Archive

Istanbul's municipal digital archive holds tens of thousands of duplicate images — and the clock is running on fixing the problem. The Istanbul Metropolitan Municipality, known by its Turkish initialism IBB, is approaching an internal review deadline set for September 2026, by which point its digitisation contractors are expected to deliver a consolidated, deduplicated database of the city's urban planning and heritage photography catalogues. The outcome will determine how accurately the city maps its own built environment at a moment when earthquake preparedness, tourism management and Bosphorus development decisions all depend on reliable visual records.

The duplication crisis is not a clerical nuisance. Istanbul sits on one of the world's most active fault systems, and after the February 2023 Kahramanmaraş earthquakes killed more than 50,000 people across southern Turkey, city planners began leaning heavily on photographic evidence to assess structural risk in older districts. When the same building facade appears under three different file names with conflicting geotag data, an engineer reviewing risk assessments remotely cannot be certain which record is current. That is the practical stakes of an issue that can sound abstract.

Where the Problem Is Most Acute

Two institutions sit at the centre of the dispute over who owns the fix. The IBB's Directorate of Urban Transformation has responsibility for structural photography of at-risk buildings across districts including Fatih and Zeytinburnu, where pre-1980 construction stock is heaviest. The Istanbul Archaeology Museums, based at Osman Hamdi Bey Square in Sultanahmet, maintain a parallel archive covering heritage structures along the old city walls and in Balat. The two systems were built on different database architectures and have never been fully reconciled. Field photographers working for both bodies have, over several years, shot overlapping areas without a shared tagging protocol, producing what one technical review — submitted to the IBB in March 2026 — described as a catalogue contamination rate requiring systematic intervention before automated tools can be effective.

The Fatih district alone, which includes the historic peninsula stretching from Saraçhane to the Theodosian Walls, contains some of the densest concentration of flagged duplicates. Contractors working under the IBB's Smart City programme, launched in 2022 with a scope covering 39 districts, have reportedly isolated more than 12,000 image pairs in Fatih alone that share geolocation data but carry different timestamps and file metadata. Resolving each pair requires a human decision: which version is authoritative, and which is archived or deleted.

The Decisions Ahead

Three choices will define whether the September deadline is met — or quietly pushed back, as it was once before in late 2025. First, the IBB must decide whether to run a centralised deduplication process through its own IT infrastructure at the Saraçhane headquarters, or to outsource the task to one of the private technology firms already contracted under the Smart City programme. The cost differential is significant: in-house processing carries lower direct spend but requires redeploying staff currently assigned to other urban data projects. Outsourcing estimates cited in procurement discussions have ranged between 4 million and 7 million Turkish lira, a figure that carries real weight given the lira's continued volatility against the euro.

Second, planners must settle on a single metadata standard going forward. The Istanbul Archaeology Museums have used a Dublin Core-derived schema; the IBB's urban transformation directorate has worked with a proprietary GIS-linked format. Harmonising these is not technically impossible, but it requires institutional agreement that has so far eluded both bodies.

Third, and most politically charged, is the question of public access. Mayor Ekrem İmamoğlu's administration has pushed a transparency agenda, and a consolidated, searchable image archive would, in principle, be accessible to journalists, academics and neighbourhood associations checking development claims. The national government, through the Ministry of Environment, Urbanisation and Climate Change, retains oversight over certain categories of urban data. Where those jurisdictions overlap on heritage images remains legally unsettled.

If the September review concludes without a resolved deduplication framework, the IBB's own timeline for completing seismic risk assessments in Zeytinburnu — currently targeted for the first quarter of 2027 — could slip. For residents in streets like Kazlıçeşme Caddesi, where 1960s apartment blocks stand beside newer construction, that delay is not an abstraction. It is the difference between receiving a structural safety rating this winter or waiting another year.