Using WebGL, you can reproject equirectangular raster tiles onto a Canvas with an orthographic projection. You can also combine the Canvas with SVG raster tiles.
WebGL is far more performant than HTML5 Canvas. For a comparison, see Raster Reprojection I.
The image is from Wikimedia Commons and described thus:
Heightmap of Earth’s surface (including water and ice) in equirectangular projection, normalized as 8-bit grayscale, where lighter values indicate higher elevation. Sea level is shown as #0c0c0c.