The Early Data Visualisation Toolkit establishes the virtual 3D, photorealistic, and standards-compliant foundations to communicate and validate local nature-based interventions. This deliverable consists of two integrated components: a written report detailing the conceptual, stakeholder-centric development process, and an online web-based visualisation platform.

By compiling remote-sensing data, drone photogrammetry, and existing municipal GIS layers, the toolkit constructs highly realistic 3D models for three active pilot sites: Barcelona, Helsinki, and Birštonas.

The primary objective of this deliverable is to support the project's co-creation methodology across all spatial scales. The toolkit allows citizens, planners, and politicians to navigate virtual environments, simulate solar shading, measure real-world distances, and overlay site-specific NbS designs —enabling a shared, democratic understanding of urban transformations before physical construction starts.

Primary Audience:

• Municipal Officers, Urban Planners, and Architect

• Local Residents, Civic Groups, and Community Leaders

• GreenInCities Consortium Technical Partners

• Pilots Coordinators

Secondary Audience:

• The 112 Climate-Neutral and Smart Cities network

• Web-GIS and 3D Software Developers

The visualization toolkit was built through a multi-stage Contextual Design and engineering process:

• Stakeholder mapping: Adopting the stakeholder classification matrix to map user needs, potential engagement barriers, and technical scenarios across six distinct target user classes.

• Reality capture and photogrammetry: Deploying unmanned aerial vehicles (UAVs/drones) on-site to capture high-density photographs and coordinates, which were then processed using photogrammetry pipelines to construct textured 3D reality meshes.

• 3D model compilation: Integrating the photogrammetry meshes with existing GIS datasets, terrain layers, and open-access formats (such as Cesium 3D tiles) to create unified spatial baselines.

• Interactive interface programming: Setting up a WebGL-based viewer with custom, user-friendly control layouts (Move, Zoom, Tilt, Rotate) and basic technical utilities (measuring tape tool, real-time date/time solar shadow rendering).

• Interoperability and data broker testing: Conducting interface tests to prepare the toolkit to consume live IoT streams from Yggio Data Marketplace (see D4.2) and export GeoJSON microclimate maps from the thermal simulations (see D.4.3).

The visualization toolkit delivers an immersive, interactive digital environment that maps physical pilot areas into a shared web-GIS platform through several core functional capabilities:

• Interactive, web-based 3D reality models are fully deployed and accessible for the active pilot locations of Barcelona (Besòs River), Helsinki (Malmi/Longinoja), and the follower city of Birštonas.

• Accessible browser-based controls are built directly into the interface, enabling non-technical users to easily navigate, measure physical distances in the virtual world, and run seasonal solar shadow simulations.

• The system allows users to visually overlay 3D designs of proposed nature-based solutions—such as green schoolyards, birdwatching towers, or vertical green facades—directly onto the photorealistic reality meshes .

• Dedicated spatial tools are structurally mapped to support all three phases of the citizen-led urban intervention cycle: Co-Analysis, Co-Design, and Co-Monitoring.

The practical application of this 3D spatial framework is projected to transform the participatory planning landscape by driving several key strategic outcomes:

• Complex environmental, spatial, and IoT dataset listings are translated into highly accessible, realistic 3D visual formats that are easy for non-expert citizens and local groups to comprehend.

• Public trust and social acceptance are strengthened by allowing residents to visually compare "before and after" intervention scenarios, fostering transparency and co-ownership.

• Municipal capital investments are de-risked by enabling technical teams to test the aesthetic, microclimatic, and spatial feasibility of nature-based solutions virtually before physical construction begins.

• A robust technical pathway is established for cross-domain interoperability, demonstrating how open-source WebGL environments can successfully harmonize 3D files, GeoJSON layers, and live API streams.

This deliverables includes links to the online toolkit with 3D models of pilot sites.