Rio's Urban Archives Scramble to Root Out Duplicate Images Clogging the City's Digital Records

Rio de Janeiro's municipal information systems are carrying tens of thousands of duplicate image files that have quietly degraded the performance of public databases managed by the Prefeitura do Rio, according to a review of technical documents circulating inside the Secretaria Municipal de Fazenda this week. The problem, which administrators have acknowledged internally, came into sharper focus on Thursday when technicians flagged a backlog affecting at least three separate digital archival platforms used for urban planning and heritage documentation.

The issue matters because the city is mid-way through its Plano Diretor revision cycle, the decennial urban master plan process that depends heavily on photographic evidence to support zoning proposals and neighbourhood classification decisions. Planners relying on geo-tagged image databases to document areas from Madureira to the Zona Portuária have been encountering mislabelled or redundant files that slow searches and, in some cases, return the wrong location data entirely.

Where the Problem Shows Up on the Ground

Two institutions sit at the centre of this week's cleanup effort. The first is the Arquivo Geral da Cidade do Rio de Janeiro, housed on Rua Amoroso Lima in the Cidade Nova neighbourhood, which maintains hundreds of thousands of digitised historical photographs dating back to the nineteenth century. Staff there confirmed this week that a migration carried out in late 2024, intended to shift files to a new content management system, appears to have created duplicate entries for roughly 14 percent of the institution's digitised collection — a figure that represents more than 40,000 individual image records.

The second institution is the Instituto Pereira Passos, the city's official urban research body, whose databases supply imagery to the Secretaria Municipal de Urbanismo for planning approvals. Technicians working out of the institute's offices near Praça XV de Novembro have been running deduplication scripts since Monday, July 1, targeting files tagged to neighbourhoods including Santa Teresa, Tijuca and parts of the Baixada de Jacarepaguá, where development pressures have made accurate visual records especially contentious.

The Arquivo Geral's 14 percent duplication rate may sound manageable, but the practical consequences are not trivial. Each duplicate file occupies server space on infrastructure that the Prefeitura rents rather than owns outright, meaning redundant data carries a direct financial cost. Municipal technology contracts in Rio, under the framework established by Decreto Municipal 49.597 of 2022, are priced partly by storage volume. Independent estimates from IT procurement specialists put cloud storage costs for municipal bodies in Rio at roughly R$0,08 per gigabyte per month — a modest unit price that adds up quickly when duplicated image libraries run into the terabytes.

What the City Plans to Do Next

The Secretaria Municipal de Ciência e Tecnologia has given both institutions until July 31 to submit deduplication reports as part of a broader data governance initiative called Dados Cariocas, launched in March 2026. The initiative set a target of reducing redundant data across city systems by 30 percent before the end of the fiscal year in December. Thursday's audit results suggest that target is achievable for image files specifically, provided the cleanup scripts currently running at the Instituto Pereira Passos can be extended to the Arquivo Geral's legacy systems, which use an older cataloguing protocol incompatible with standard automated tools.

For community groups and researchers who regularly download historical photographs from the Arquivo Geral's public portal — including neighbourhood associations in Lapa and the urban history faculties at UFRJ and PUC-Rio — the immediate advice from archivists is to cross-reference file metadata before citing images in publications or planning submissions. Duplicate records can carry conflicting captions and coordinates, meaning a photograph labelled as depicting the Largo do Machado could be associated with geotag data pointing to a different part of Catete entirely.

Archivists at Cidade Nova say the deduplication work should be largely complete for the most-accessed portions of the collection — photographs from 1950 to 1990 — by mid-July. Older and more fragile digitised material, including glass plate negatives from the early twentieth century, will take longer. The full archive is expected to be clean and reliably searchable again before the Plano Diretor's public consultation phase reopens in September.