Central Coast Takes a Cautious Line on AI Image Duplication as Global Cities Race Ahead

Central Coast Council is still working through a backlog of digitised planning documents that contain duplicate or mismatched imagery — a problem that has quietly dogged its records system since the local government body emerged from state administration in 2021. The issue is not unique to the Central Coast, but how the council is approaching it sits in sharp contrast to what comparable mid-sized cities overseas are already doing.

The timing matters. Sydney recorded its hottest June since 1859 this year, a fact that is accelerating climate resilience planning across the region. Councils lodging flood-mapping data, bushfire overlays and coastal erosion assessments are increasingly relying on geotagged photography and satellite imagery captured at specific dates. When duplicate images slip into those records — the same photo filed under two different survey dates, for instance — the downstream consequences for planning decisions on streets like Donnison Street in Gosford CBD or Etna Street in North Gosford can be significant.

What the council is actually doing

Central Coast Council's geographic information systems team, housed within the Environment and Planning directorate, has been running a manual audit of imagery attached to development applications lodged through the NSW Planning Portal since at least mid-2024. The portal, managed by the NSW Department of Planning, Housing and Infrastructure, requires applicants to upload site photographs as part of the application package. Duplicate image submissions — often the result of automated form-filling software re-attaching the same file — have created version-control problems in council's own GIS layers.

The Gosford CBD renewal project, centred on the precinct between Mann Street and the Gosford waterfront, has been one of the most document-heavy planning zones on the coast in the past two years. Multiple development applications for that strip have involved large imagery bundles. Council officers have reportedly been cross-referencing image metadata manually rather than through automated deduplication software, a process that planning professionals describe as time-intensive given the volume of submissions flowing through the portal.

The Central Coast's approach lags behind what cities of similar population scale are doing elsewhere. Vienna's municipal planning authority, MA 41 — Stadtvermessung, the city's official surveying department — deployed automated hash-based image deduplication across its public GIS infrastructure in 2023, covering more than 4.2 million cadastral records. Toronto's City Planning division integrated AI-assisted duplicate detection into its ePlans system during a 2024 upgrade, with the city publicly reporting a reduction in document processing time. Both cities serve populations in the 2.5 to 2.9 million range, larger than the Central Coast's roughly 350,000 residents, but the underlying technical problem — ensuring that each planning image is uniquely and accurately time-stamped — is identical regardless of scale.

The cost of getting it wrong

Inaccurate imagery in planning records carries real financial risk. In NSW, a development application that relies on a flood-risk photograph taken in a dry period but filed against a post-flood survey date could affect insurance valuations or trigger appeals. The NSW Land and Environment Court has seen a growing number of cases in which the provenance of site photography has been contested; while no specific Central Coast case has been cited publicly on this issue, the legal exposure is broadly understood within the planning sector.

For residents in lower-lying suburbs like Narara or along the Wyong River corridor near Tuggerah, the accuracy of flood imagery in council's GIS system is not an abstract concern. Flood insurance premiums on the Central Coast have risen sharply since 2022 following the eastern Australia flood sequence, and any uncertainty about the integrity of the underlying mapping data adds another layer of difficulty for homeowners already squeezed by mortgage costs on properties they bought partly because of proximity to Sydney.

Central Coast Council has not publicly announced a procurement process for automated deduplication tools, but the NSW Government's ongoing push to standardise digital planning infrastructure across councils — part of the broader ePlanning reform agenda — may effectively force the issue. Councils that have not aligned their internal systems with state portal standards by the end of the 2026-27 financial year face compliance reviews. That deadline gives the Central Coast roughly 12 months to close the gap with peers that moved earlier and faster.