altitudeMode

How altitudeOffset is anchored.

• AltitudeMode.ABSOLUTE (default): offset adds to the tileset's baked altitude.

• AltitudeMode.RELATIVE_TO_GROUND: offset is meters above terrain at altitudeAnchor (lookup runs against earth.worldwind.globe.Globe.getElevation).

• AltitudeMode.CLAMP_TO_GROUND: tileset is shifted so its anchor altitude matches terrain at the anchor, then altitudeOffset lifts it from there. Non-ABSOLUTE modes refresh each frame so the offset auto-adjusts as elevation tiles load. For globe-spanning tilesets (Google Photorealistic) the single-anchor up direction stops making sense — use ABSOLUTE + offset = 0 there.