First step into describing Netherlands3D clearly as a platform and an…

… overview of the architecture

docs/docs/developers/platform-architecture.md

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+Netherlands3D is a comprehensive platform designed to develop specialized 3D viewers that unify geospatial data from
+various sources. By integrating information from multiple parties, it enables organizations to visualize, analyze, and
+interact with spatial data in one centralized, interactive 3D environment. This approach transforms individual datasets
+into a cohesive, integral viewer, providing insights and context that would be hard to achieve by viewing data in
+isolation.
+
+## A Platform for Building Custom Viewers
+
+Netherlands3D stands out as a flexible solution for creating tailored viewers suited to specific use cases. Its modular
+design, composed of individual Unity packages, allows developers to select and combine only the components they need.
+Each viewer built with Netherlands3D can be as simple or as complex as the project demands, with the ability to
+incorporate advanced functionalities such as live data updates, 3D rendering of large datasets, and interactive tools
+for exploration.
+
+## Centralized Data Integration
+
+The platform’s core strength lies in its capacity to aggregate data from multiple external sources, including GIS
+databases, real-time sensor feeds, and specialized geospatial services. Netherlands3D acts as a data integrator,
+gathering disparate data streams and presenting them in a unified 3D viewer. This enables users to work within a single
+environment while accessing and analyzing comprehensive spatial data from various partners and services. By bringing
+diverse datasets together, Netherlands3D supports the development of digital twins and other projects requiring
+up-to-date and holistic data views.
+
+## Core Components
+
+### Building Blocks (Unity Packages)
+
+![Building Blocks](../imgs/building-blocks.png){ align=right width="150" }
+Building blocks are the fundamental components of the Netherlands3D platform, each packaged as a Unity module with a
+specific function. These packages manage key tasks within the viewer -such as data handling, layer management, 
+and integrations with OGC standardized services- and can be added or removed independently to suit the viewer’s 
+purpose.
+
+Each package is designed to be modular, allowing developers to choose only the components required for a particular
+project. This modularity supports the integration of data from various sources, such as GIS services and sensor
+networks, into a cohesive and interactive 3D viewer. By breaking down functionality into separate, reusable Unity
+packages, Netherlands3D simplifies maintenance and scalability, making it easy to adapt the viewer to evolving needs and
+datasets.
+
+### Functionalities
+
+![Functionalities](../imgs/functionalities.png){ align=right width="275" }
+Functionalities are specialized modules that encapsulate the capabilities of Netherlands3D’s core building blocks. These
+functionalities handle unique tasks or provide interactions that enrich the viewer. Examples include urban development, 
+live sensor data overlays, and environmental simulation tools.
+
+The modular nature of functionalities allows them to be activated or configured on a per-project basis. By
+offering specific, configurable tools, functionalities make it easy for end-users to create viewers that cater to 
+specialized use cases. This flexible setup also enables developers to integrate real-time data or add interactive
+features, fostering engagement and insight through data visualization.
+
+### The "Twin" Application
+
+The Twin application provides a foundational viewer setup, pre-configured with essential building blocks and a selection
+of baseline functionalities. Designed to help users get started quickly, Twin offers an accessible path for building on
+the platform, providing a solid base configuration that can be expanded as needed.
+
+In addition to being a starting template, Twin also serves as an _incubator_ for Netherlands3D’s development team. New
+building blocks and functionalities are developed, tested, and refined within Twin before being packaged independently.
+This process allows the development team to evaluate how emerging functionalities interact within a full viewer context,
+addressing any issues early and ensuring seamless integration into the larger ecosystem.
+
+Once a new module or functionality reaches a level of stability and maturity, it is moved into its own Unity package,
+making it available for integration into other projects. This approach fosters innovation within a controlled
+environment, accelerating development while maintaining reliability.
+
+_You can see the code at [https://github.com/Netherlands3D/twin](https://github.com/Netherlands3D/twin) or see it in
+action at [https://netherlands3d.eu/twin](https://netherlands3d.eu/twin)._

mkdocs.yml

@@ -9,10 +9,16 @@ nav:
   - 'Voor ontwikkelaars':
       - 'docs/developers/introduction.md'
       - 'docs/developers/quickstart.md'
+      - 'Platform Architecture':
+        - 'Platform Overview': 'docs/developers/platform-architecture.md'
+        - 'docs/developers/functionalities.md'
+#      - 'Getting Started':
+#        - 'docs/developers/getting-started/using-the-twin.md'
+#        - 'docs/developers/getting-started/from-scratch.md'
+#        - 'docs/developers/getting-started/your-own-functionality.md'
       - 'Core Concepts':
           - 'Overview': 'docs/developers/core-concepts.md'
           - 'docs/developers/projects.md'
-          - 'docs/developers/functionalities.md'
           - 'docs/developers/layers.md'
           - 'docs/developers/layers-with-authentication.md'
       - 'Features':