Coordinate systems
Comparison
| TissUUmaps | OpenSeadragon | WebGL | Description |
|---|---|---|---|
| Data/object | Image | Local/object | Raw data (i.e. pixel) coordinates |
| Layer | Coordinate system shared among objects of different resolution, e.g. physical coordinates | ||
| World | Viewport | World | Global coordinate system in which the layers are positioned, e.g. after registration |
Viewport [0, 1] | Web [0, canvas size] | Normalized device coordinates (NDCs) [-1, 1], equivalent to clip space when using orthographic projections for 2D rendering | The part that is currently visible in the browser (i.e., the HTML canvas element) |
| Device | Physical device (i.e. screen) pixels |
Transformations
| Direction | Transformation |
|---|---|
| Data -> Layer | layer coordinates = object-level similarity transform * data coordinates |
| Layer -> World | world coordinates = layer-level similarity transform * layer coordinates |
| World -> Viewport | viewport coordinates = (world coordinates - viewport origin) / viewport size |
| Viewport -> Device | device coordinates = device pixel ratio * viewport coordinates |
User-configurable variables are highlighted in bold.