Geospatial

This SDK is designed to handle data with real-world geographic context. It provides tools for georeferencing project data and rendering global map tiles.

Georeferencing

Data usually exists in one of two states: a geographic location (Latitude/Longitude), or a projected coordinate in a local 3D workspace. The fsl_transform library bridges these worlds by providing a geospatial-aware transformation hierarchy:

1. Coordinate Reference Systems (CRS): Support for standard WGS84 Latitude/Longitude, UTM (Universal Transverse Mercator), and custom PROJ pipeline transformations.
2. Ellipsoids: Earth’s shape is modeled using standard ellipsoids like WGS84 or GRS80 to maintain precision in distance and area calculations.
3. Projections: The SDK handles standard EPSG projections and unprojected geocentric systems like ECEF for true 3D global visualization.

Geospatial Transformation Hierarchy

Unlike standard local transforms, the SDK supports geospatial transforms that place entities directly into a global coordinate system. This is achieved using specialized components that store coordinates in a specific CRS.

These transforms integrate with the double-precision transformation system to ensure high-precision placement and jitter-free rendering, even at planetary scales.

Workflow: From Lat/Long to Viewport

Bringing survey data into a project involves establishing a Spatial Triad. This structure defines how a geographic projection, an origin point, and a scale factor combine to create a local coordinate system.

Once a Triad is established, you can use the Geo-Context resource. This global source of truth ensures all plugins use a consistent project location. By updating the Geo-Context, you can change projections (for example, switching from a global ECEF view to a local UTM zone) while coordinate conversions are handled by the engine.

Web Map Tile Service (WMTS)

The SDK includes a Web Map Tile Service (WMTS) renderer. This allows you to contextualize 3D data, such as drone surveys or engineering designs, within global satellite imagery and terrain.

Quadtree Map Rendering

The map renderer uses a quadtree-based approach to stream tiles from services like ArcGIS, Mapbox, or OpenStreetMap. By loading tiles dynamically based on the current view, the SDK provides a global map experience while optimizing memory usage.

The renderer can also consume elevation data to create 3D terrain surfaces. You can configure custom tile server endpoints for both imagery and terrain.

Switching Projections

The SDK can handle multiple geographic projections on the fly. This is useful for professionals who need to view a project in a global context (ECEF) and then switch to a local engineering grid (UTM) for detailed work.

The transition is handled by automatically reprojecting map tiles, UI elements, and coordinate labels. If you change the global GeoProjection, measurements and labels update to reflect the new coordinate system.

Developer Integration

Integrating geospatial features into a plugin is handled through the GeoContext and SceneCoordinateSystem resources.

The SceneCoordinateSystem defines the target coordinate system for the active scene, while GeoContext manages the project-wide spatial context including origin and scale.

Roadmap: Model Warping

While the engine can switch projections for map data, reprojecting large 3D models and point clouds at the vertex level is more complex. Potential approaches include:

1. Affine Warp: Using efficient linear transformations to approximate reprojection for smaller models.
2. Per-Vertex Reprojection: Developing pipelines for accurate reprojection of all points or vertices for maximum precision.