Istanbul's Digital Archives Get a Cleanup: What Happened This Week in the City's Fight Against Duplicate Images

Istanbul's three largest municipal digital platforms flagged a combined backlog of more than 40,000 duplicate image files this week, according to internal notices circulated by the Istanbul Metropolitan Municipality's IT directorate. The problem is not new, but a push to digitise urban planning records ahead of the municipality's 2026 earthquake-preparedness audit has brought it to a head in recent days.

The timing matters. Since the February 2023 Kahramanmaraş earthquakes killed more than 50,000 people across southern Turkey, Istanbul has accelerated its effort to build comprehensive digital inventories of every building, street and utility corridor in the city. Duplicate images — often uploaded multiple times across different departments or by different contractors — slow database queries, inflate storage costs and, more critically, create confusion in emergency-response mapping systems. When a rescue team pulls up a grid reference and finds four nearly identical, poorly labelled photographs of the same Fatih apartment block, they lose precious seconds.

Where the Problem Is Showing Up

The immediate flashpoint this week was the IBB Açık Veri Portalı, the Metropolitan Municipality's open-data portal, where technical staff identified roughly 18,000 redundant image entries tied to the city's ongoing Bosphorus coastline documentation project. That project, which began cataloguing waterfront structures from Rumeli Kavağı in the north down to Ahırkapı lighthouse in the south, has involved dozens of subcontractors uploading photographs independently — with no unified naming convention or hash-check system to catch repeats before they enter the database.

Separately, Tapu ve Kadastro Genel Müdürlüğü — the General Directorate of Land Registry and Cadastre, which operates a major regional office on Şişli's Büyükdere Caddesi — has been running its own deduplication sweep since late June. The directorate manages property photographs attached to title-deed records, and staff have been manually reviewing entries flagged by automated software. Real estate agents working in Beşiktaş and Kadıköy told colleagues this week that some property listing images temporarily disappeared from the official cadastre interface during the review — a disruption that complicated several pending sales.

The third affected platform is the Istanbul Cultural Heritage Documentation System, maintained by the Directorate General of Foundations (Vakıflar Genel Müdürlüğü) in coordination with the municipality. That database holds photographs of Ottoman-era structures from neighbourhoods including Balat, Zeyrek and Süleymaniye. A deduplication pass begun on June 30 found that some mosques and hans had been photographed and uploaded by as many as six separate field teams since 2021, creating layered redundancy across an archive that now holds upward of 2.3 million image files.

What Happens to the Data Now

The IBB's IT directorate is moving toward a perceptual hashing standard — a technology that compares image content rather than file names — to catch near-identical photographs that differ only in compression or metadata. A tender for the software implementation was listed on the Republic of Turkey's Public Procurement Authority (Kamu İhale Kurumu) portal on July 2, with a submission deadline of July 28. The estimated contract value in the tender notice was listed at 4.2 million Turkish lira, roughly 115,000 US dollars at current exchange rates.

For the Vakıflar database, staff have been given until September 15 to complete manual verification of flagged records — a tight window given that the heritage archive spans dozens of districts and the field teams responsible for many of the original uploads have since changed. Files confirmed as duplicates will be archived in a read-only repository rather than deleted outright, a precaution against permanently losing unique metadata attached to what look like identical photographs.

Property buyers and real estate professionals dealing with cadastre listings should expect intermittent image gaps in the official online system through mid-July, when the Tapu directorate expects to complete its first deduplication pass. Anyone who finds a missing photograph attached to a title-deed record is advised to contact the Şişli branch directly, or use the e-Devlet portal to submit a query. The broader lesson from this week's scramble is straightforward: as Istanbul's digital infrastructure expands under earthquake-preparedness pressure, the unglamorous work of data hygiene is proving just as urgent as the survey work itself.