Istanbul's War on Duplicate Street Imagery Lags Behind London and Seoul — But a Fix Is Coming

Istanbul's municipal mapping archive holds tens of thousands of duplicate street-level images — photographs taken multiple times of the same façade, the same alley, the same Bosphorus-facing balcony — cluttering the databases that planners, emergency responders, and heritage officers rely on daily. The Istanbul Metropolitan Municipality's GIS directorate acknowledged the problem in a January 2026 internal review, flagging that roughly one in five images stored across its urban-planning platforms was either a near-identical copy of another file or depicted a structure that no longer exists.

The timing matters. Post-earthquake risk assessments, accelerated after the February 2023 Kahramanmaraş disaster, depend on accurate, current photographic records of building stock. Duplicate or outdated images — showing a reinforced façade that has since been demolished, or a crack that has already been repaired — can send structural engineers to the wrong address or cause them to miss a genuinely at-risk building. With the Istanbul Earthquake Risk Mitigation and Emergency Preparedness Project still active and the city carrying a well-documented seismic exposure, image database hygiene has moved from a bureaucratic nicety to a public-safety question.

What Istanbul Is Actually Doing

The municipality launched a deduplication pilot in the Fatih and Beyoğlu districts in March 2026, contracting the work to a local geospatial firm through a procurement notice published on the Public Procurement Authority's (KİK) e-procurement portal. The pilot covers approximately 14,000 image records tied to historic structures along the İstiklal Caddesi corridor and the old city walls near Yedikule. Under the contract, automated perceptual-hash algorithms flag near-duplicate images for human review, with a target of reducing redundant files by 40 percent before the pilot concludes at the end of August 2026.

Separately, the Boğaziçi İmar Müdürlüğü — the directorate overseeing development along the Bosphorus shoreline — has been running its own, narrower image-audit programme since late 2025, focused on the Arnavutköy and Bebek waterfronts where illegal construction complaints have historically been highest. That directorate cross-references its photographic records against satellite imagery updated quarterly by the General Directorate of Geographic Information Systems (TKGM) in Ankara.

Progress, in short, is happening in patches rather than as a coordinated city-wide programme.

How Istanbul Compares to London and Seoul

London's Ordnance Survey completed a city-wide deduplication sweep of its Urban Photographic Index in 2024, reducing its street-level archive by approximately 31 percent and integrating the cleaned dataset directly into the Greater London Authority's planning portal. Seoul, which manages one of the densest urban-image archives in Asia through its SmartSeoul platform, automated the process through a machine-learning pipeline rolled out between 2023 and 2025, cutting manual review time by an estimated 60 percent according to the Seoul Digital Foundation's 2025 annual report.

Istanbul's population — officially around 15.8 million as of the Turkish Statistical Institute's 2024 address-based register — dwarfs both those cities, which partly explains the scale of the challenge. But the fragmented governance structure compounds it. At least four separate municipal and national directorates maintain photographic databases that overlap geographically but do not currently share a unified deduplication standard. London consolidated its datasets under a single GLA data-sharing agreement; Seoul used a national smart-city budget allocation. Istanbul has neither instrument in place yet.

The practical consequences show up at street level. Planners working on the contested redevelopment of the Haydarpaşa train station zone on the Asian shore have reported, in documents reviewed as part of a public consultation process, that conflicting image records have complicated environmental-impact modelling. The station's surrounding warehouses have been photographed dozens of times by different agencies over the past decade, with versions tagged to different coordinate points.

The municipality's broader Digital Istanbul 2030 strategy, published in draft form last year, does include a unified geospatial data standard as a medium-term goal, with a target implementation date of 2028. Whether the March pilot in Fatih and Beyoğlu generates enough political momentum — and budget — to accelerate that timeline will become clearer when the pilot's findings are presented to the city council's urban transformation committee, currently scheduled for September 2026. Residents and developers waiting on planning decisions tied to earthquake-risk categories have a direct stake in that meeting.