Istanbul's War on Duplicate Street Photography: How the City Stacks Up Against Amsterdam, Seoul and Lisbon

Istanbul's Metropolitan Municipality confirmed earlier this year that its urban documentation archive, maintained through the IBB (İstanbul Büyükşehir Belediyesi) Geographic Information Systems directorate, had accumulated tens of thousands of duplicate street-level images — some neighbourhoods photographed multiple times by different contractors, with no unified deduplication protocol in place. The redundancy has slowed planning processes, inflated storage costs and complicated earthquake-risk assessments that rely on accurate, up-to-date visual records of ageing building stock.

The timing matters. Since the February 2023 Kahramanmaraş earthquakes exposed the depth of Turkey's unsafe-building crisis, Istanbul's planners have been under sustained pressure to produce clean, reliable structural inventories of vulnerable districts. Duplicate or misfiled imagery — photographs of the same crumbling facade in Fatih or Balat catalogued under two different project codes — can throw off damage-risk models. With a major seismic event widely expected along the North Anatolian Fault line running beneath the Marmara Sea, the administrative cost of messy data is no longer abstract.

What Istanbul Is Actually Doing

The IBB's Digital Transformation Office, operating out of its Saraçhane headquarters near the Şehzadebaşı district, launched a pilot deduplication programme in late 2024 covering the historic peninsula's cadastral photography. The project uses perceptual hashing — an algorithmic method for identifying near-identical images — rather than simple file-name matching, which had previously failed to catch photos taken seconds apart by different field teams. The Fatih and Beyoğlu district municipalities are both participating in the pilot, which as of June 2026 had processed roughly 140,000 image files from the two districts alone.

TMMOB, the Union of Chambers of Turkish Engineers and Architects, has pushed for the programme to be extended across all 39 Istanbul districts before the end of 2026. The organisation has argued — in general terms at public forums held at its İstanbul branch office in Nişantaşı — that inconsistent visual documentation hampers licensed architects tasked with urban transformation projects, particularly in at-risk neighbourhoods along the European shore of the Marmara.

Costs are real. Municipal cloud storage for the IBB's GIS division reportedly expanded significantly between 2021 and 2025, a period when multiple overlapping street-documentation contracts ran simultaneously. City officials have not published a specific figure for wasted expenditure attributable to duplicate files, but the deduplication pilot has been framed internally as a cost-recovery measure as much as a data-quality one. Turkish lira depreciation has made foreign cloud-storage contracts — typically priced in dollars or euros — an increasingly painful line item for municipal budgets.

How Istanbul Compares to Amsterdam and Seoul

Amsterdam's municipal archive, the Stadsarchief Amsterdam, completed a comparable rationalisation of its public-space image holdings in 2023, consolidating records going back to the 1990s into a single deduplicated repository accessible to urban planners and the public through a unified portal. The Dutch project benefited from more stable funding conditions and a smaller geographic footprint — Amsterdam covers roughly 219 square kilometres against Istanbul's 5,461.

Seoul offers a more instructive parallel. The Seoul Metropolitan Government's Smart City Data Hub, operational since 2022, embedded automated deduplication at the point of image ingestion, meaning field cameras uploading to the city's system are checked against existing records in real time. Istanbul is essentially retrofitting that logic onto a legacy archive rather than building it in from the start — a distinction that matters for both timeline and cost.

Lisbon, dealing with post-earthquake structural surveys of its own Pombaline downtown, adopted a hybrid model in 2024 that contracts a private GIS firm for deduplication while retaining public-sector oversight of the final verified archive. Istanbul's current approach keeps the work in-house, which preserves institutional knowledge but has moved more slowly.

For residents in Balat, Zeyrek or other heritage zones undergoing urban transformation reviews, the practical upshot is straightforward: applications for structural assessments linked to building renovation permits should expect faster processing as the deduplicated archive expands district by district through the second half of 2026. The IBB's GIS portal already allows property owners to check whether their building's photographic record has been verified and cleared — a small but concrete sign that the back-end work is beginning to reach street level.