Istanbul's War on Duplicate Urban Images: How the City Stacks Up Against Amsterdam and Seoul

Istanbul's metropolitan municipality has been quietly working through a backlog of thousands of duplicate photographs embedded in its urban planning and heritage documentation databases — identical or near-identical images that, when counted separately, have inflated assessments of surveyed sites, skewed restoration budgets, and fed inaccurate records to national planning bodies in Ankara. The scale of the problem only became clear after an internal audit of the IMM's (Istanbul Metropolitan Municipality) digital asset management system was completed in the spring of 2026.

The timing matters. Istanbul sits at an intersection of pressures that make clean, reliable visual documentation unusually consequential. The city is still processing lessons from the February 2023 Kahramanmaraş earthquakes, which forced a rapid and sometimes chaotic expansion of structural risk mapping across older Istanbul districts. Neighborhoods like Fatih, Balat, and parts of Üsküdar were re-photographed at speed, with different teams uploading assets to overlapping repositories. The result was a catalog riddled with redundancy — the same crumbling wall documented six times, the same reinforced pillar logged as evidence at three separate addresses.

What Istanbul Is Doing About It

The IMM's Directorate of Urban Transformation has been piloting a deduplication protocol since January 2026, built around perceptual hashing technology — software that generates a fingerprint for each image and flags matches even when files have been resized, recompressed, or renamed. The pilot covers roughly 140,000 images tied to the Tarihi Yarımada (Historic Peninsula) documentation project, which spans the area from Sultanahmet to the Theodosian Walls. Officials aim to extend the protocol to the full municipal archive, estimated at more than 1.2 million image files, by the end of the third quarter.

The project is being coordinated partly through a technical partnership with TMMOB, the Union of Chambers of Turkish Engineers and Architects, which has been pressing for standardized digital records across municipal systems since at least 2024. TMMOB's Istanbul branch office, headquartered near Taksim Square, has hosted working sessions with municipal IT staff on data governance standards. The broader effort connects to a European Union pre-accession technical assistance program that allocated €4.2 million to Turkey for smart-city infrastructure improvements in the 2024–2026 funding cycle, though Istanbul's deduplication work is internally funded.

How Istanbul Compares to Amsterdam and Seoul

Amsterdam began a comparable overhaul of its municipal image archive in 2022, working through the Stadsarchief Amsterdam. That institution manages roughly 750,000 digitized historical images and implemented automated deduplication as part of a broader metadata standardization project. The Dutch capital completed its first full pass by mid-2023, a timeline Istanbul will not match — partly because Istanbul's archive is significantly larger and partly because the 2023 earthquake response added tens of thousands of rushed uploads that lacked consistent metadata tagging from the outset.

Seoul offers a more relevant comparison in scale. The Seoul Metropolitan Government manages a smart-city data platform called S-DoT, which integrates visual data from urban sensors and fieldwork teams across 25 autonomous districts (gu). Seoul introduced image-hash deduplication across its construction and zoning photography databases in 2021, reducing what city officials described at the time as a 14 percent redundancy rate in active project files. Istanbul's internal audit has not published a comparable figure publicly, but the scope of the Tarihi Yarımada pilot alone suggests the problem runs deep in districts with the heaviest documentation activity.

For residents and property owners in neighborhoods like Zeyrek, Fener, or along the Bosphorus shoreline where development disputes frequently hinge on photographic evidence, the practical consequence of duplicate records is significant: an image logged twice can appear to corroborate a claim it only makes once, and an inflated survey can misdirect restoration funding or delay demolition orders on unsafe structures. Getting the archive clean is not an administrative formality. It is a precondition for the accuracy of every decision that follows.

The IMM plans to publish a progress report on the deduplication project in September 2026. Property owners with pending applications tied to urban transformation zones — particularly in Fatih and Kadıköy districts — should confirm with their case officers that documentation submitted before January 2026 has been reviewed under the new protocol to avoid processing delays.