intersectsShadowCasterRegion

True when a shadow-casting bounding sphere outside the view frustum still intersects a valid cascade's light-space box - its shadow can reach visible ground. Requires the shadow layer to have rendered earlier in the layer list (shadowState set). Only the first ShadowState.offscreenCasterCascades cascades recruit (app-tunable via earth.worldwind.layer.shadow.ShadowLayer.offscreenCasterCascades): the coarse cascades' texels span metres, so an off-screen caster's shadow there is sub-texel noise, and their huge light boxes would keep distant content alive wholesale. Visible casters still draw into every cascade.