Is there a script to merge terrain tiles into one terrain?

Here a script i wrote to merge the heightmaps of 256 terrains into a single terrain heightmap. using System.Collections; using System.Collections.Generic; using System.IO; using UnityEngine; using UnityEditor;

 [ExecuteInEditMode]
 public class CreateBigTerrain : MonoBehaviour
 {
     
     public Terrain _bigTerrain;
     public Terrain _tiles;
     public TerrainData tData;
     public RenderTexture tileHeightmap;
     public RenderTexture newHeightmap;
     public bool active=true;
     private int progressId;
     
     IEnumerator Start()
     {
         if(active)
         {
             // Create a new progress indicator
             progressId = Progress.Start("Merging Terrain");
             
             yield return StartCoroutine("Calculate");
 
             // The task is finished. Remove the associated progress indicator.
             Progress.Remove(progressId);
             active=false;    
             StopAllCoroutines();
         }
         DestroyImmediate(this);
 
     }
 
     IEnumerator Calculate()
     {
         TerrainData terrainData; 
         string path; 
         bool flipVertical=false;
         Vector2 inputLevelsRange;
         
         //_bigTerrain = GameObject.Find("bigTerrain").GetComponent<Terrain>();
         
         int heightmapWidth = 1024;
         int heightmapHeight = 1024;
 
         float normalize = (1 << 16);
         byte[] data = new byte[4096 * 4096 * 2];
         
         for(int y=0; y<16; y++)
         {
             for(int x=0; x<16; x++)
             {
                 _tiles = GameObject.Find("Terrain_"+x+"_"+y+"-20210513 - 125829").GetComponent<Terrain>();
                         
                 tData = _tiles.terrainData;
 
                 float[,] heights = tData.GetHeights(0, 0, 1024, 1024);
 
 
                 for (int ty = 0; ty < 256; ++ty)
                 {
                     for (int tx = 0; tx < 256; ++tx)
                     {
                         int index = (x*256+tx)+(y*256+ty)*4096; //tx*4 + ty*4 * 1024;
                         //int srcY = flipVertical ? 1024 - 1 - y : y;
 
                         float remappedHeight = heights[ty*4, tx*4];// * (inputLevelsRange.y - inputLevelsRange.x) + inputLevelsRange.x;
 
                         int height = Mathf.RoundToInt(remappedHeight * normalize);
                         ushort compressedHeight = (ushort)Mathf.Clamp(height, 0, ushort.MaxValue);
 
                         byte[] byteData = System.BitConverter.GetBytes(compressedHeight);
 
                         data[index * 2 + 0] = byteData[0];
                         data[index * 2 + 1] = byteData[1];
                     }
                 }                
                 
                 
                 yield return new WaitForSeconds(0.1f);
 
                     
                 Progress.Report(progressId, x+16*y, 256,"Heightmap of Terrain_"+x+"_"+y+"-20210513 - 125829");
             }            
         }
         
 
 
         path="Assets/Heightmaps/bigTerrain";
         
 
         FileStream fs = new FileStream((path + ".raw"), FileMode.Create);
         fs.Write(data, 0, data.Length);
         fs.Close();
 
         yield return null;
     }
 
     // Update is called once per frame
     void Update()
     {
 
     }
 
 }