[Demo] added an end-user oriented demonstration of itowns capabilities

[Nynjin]

Description

This pull request introduces a new demonstration example for iTowns, adding a complete demo application under examples/demo, integrated amongst the other Itowns examples under the section Demo.

This demo section features multiple self-contained scenes with navigation, camera transitions, and layer management (visibility, controls, feature picking, recreation of view and layers from scratch, ...).

The examples/demo package can be described as such :

css/ : style for the UI elements

src/ : Typescript demo code

Config/ : global constants such as scene transition duration or distance from globe where to toggle on/off atmosphere

Layers/ : objects containing promises for itowns layered shared between multiple scenes to avoid refetching/re-instantiation, as well as methods such as feature picking which is specific to each layer

Sources/ : promises containing sources that are used by multiple layers to avoid refetching

Views/ : singletons for the different views shared between layers (globe, immersive, planar, ...) that initialize itowns views and expose extra methods/properties (visibility toggle, viewerDiv, layer insertion, instance clearing, ...)

Scenes/ : scenes used in the demo containing their methods and properties (title, description, layers, onCreate, onEnter, onExit, view)

Repositories/ : shared singleton containers such as SceneRepository (array of all used scenes)

Types/ : common types and wrappers (SceneType, or LayerType containing all types of itowns layers used)

Utils/ : global methods such as scene transition, ui update, camera movement, event propagation block, ...

Services/ : application-level services such as feature picking on click

index.ts : main demo entrypoint

index.html : entrypoint for the demo. Hosts the root containers for the UI

Motivation and Context

iTowns currently provides an unstructured collection of examples that are mainly designed for developers and are kind of tutorials in the end. This PR adds an end-user oriented demonstration of main iTowns features.
See related issue.

Environment

• OS: Windows 11
• Browser: Brave
• Node: v24.11.0
• npm: 11.6.1

Screenshots

Itowns.demo.mp4

Globe Scene	Planar Scene	Terrain Elevation Scene

Instanced Data Scene	Point Cloud Scene	BIM Scene

Textured Meshes Scene	Immersive Scene

Open questions / TODO

• Find a better 3DTiles dataset
• Find a better point cloud (bigger, with classification and RGB if possible). Which dataset can we use from the LIDAR HD ?
• Immersive and planar scene tend to be unstable (white screen sometimes, ground on immersive scene may not appear), mostly fixed with scene reset
• Add extruded lines when ready
• Move light on globe scene to not obscure the center
• Camera movement based on duration can be troublesome when switching between scenes that have the same placement, or if resetting camera position when it hasn't moved, or has barely moved (waiting 2 seconds each time and blocking the UI)

[Desplandis]

I would not be able to do a review until new year's eve (vacation time :D), @alavenant @Calvina24 could you review the functionality of this PR and dispatch the technical part to a member of the team?

[Desplandis]

@Nynjin I saw that there is a 10mB binary file in the changes, would it be possible to remove it from the commits and host it elsewhere to not pollute the main itowns repository? We usually use itowns2-sample-data for the datasets.

[Nynjin]

@Nynjin I saw that there is a 10mB binary file in the changes, would it be possible to remove it from the commits and host it elsewhere to not pollute the main itowns repository? We usually use itowns2-sample-data for the datasets.

Got it thanks, I uploaded my models there and made a PR.
Once that's done I'll update this one to remove the local models and use the uploaded ones instead.

[alavenant]

Thanks for the work.

The transition from one demo to another is smooth and enjoyable.

I suggest to put the "go local" next to "bring your data to life".

In "Feel the Relief", you could also talk about the ortho-images.

"go local" : unzoom so that we can fully appreciate the scene as a whole

Why not add a view "combine your data" with lidar, 3D objects, buildings, bim, ... ?

[Nynjin]

Thanks for the work.

The transition from one demo to another is smooth and enjoyable.

I suggest to put the "go local" next to "bring your data to life".

In "Feel the Relief", you could also talk about the ortho-images.

"go local" : unzoom so that we can fully appreciate the scene as a whole

Why not add a view "combine your data" with lidar, 3D objects, buildings, bim, ... ?

Thank you for you feedback.

I did consider putting "go local" before "bring your data to life" but having a planar view right in the middle of globe views looks a bit off, that's mostly why planar and street views are at the very end.

And when it comes to combining the data, it's an interesting idea but I'd have to check how it holds up performance-wise since clicking directly on that scene would attempt to instantiate all of these elements at the same time.