Lightmapping.GetTerrainGIChunks

public static void GetTerrainGIChunks (Terrain terrain, ref int numChunksX, ref int numChunksY);

Parameters

terrain	The terrain.
numChunksX	Number of chunks in terrain width.
numChunksY	Number of chunks in terrain length.

Get how many chunks the terrain is divided into for GI baking.