Frontend Engineering at Palantir: Polar Scaled Tiles in Zodiac

Summary

Zodiac, Palantir’s custom 3D globe library built on Three.js, encountered severe performance degradation near the Arctic because latitude/longitude tiles converge into tiny slivers and create excessive geometry. Standard equal-angular tiling was replaced internally with polar-scaled tiles whose widths expand toward the poles so their surface areas remain closer to equatorial tiles. The design uses spherical surface-area calculations, power-of-two merge spans, and dynamic quadtree expansion; client-side texture compositing handles standard geodetic or Web Mercator sources, while heightmaps are combined and resampled for wider tiles. The change reduced polar geometry, draw calls, and textures by over 90% and made frame time more consistent, though texture loading remains the next bottleneck and native polar tiles would remove stitching overhead.

Takeaways

1. 1

   Polar-scaled tiles reduce polar geometry, draw calls, and textures by over 90%, making frame time more consistent across the globe.

2. 2

   Tile spans are selected as powers of two from the ratio between equatorial maximum tile area and the area of a tile at a given latitude.

3. 3

   Client-side stitching avoids requiring tile-server changes, but a zoom-level 5 polar tile may fetch 16 source tiles before it can display.