public float[,] GetHeights(int xBase, int yBase, int width, int height);

public Terrain ter;
public TerrainData  terr; // как указать ассет тераина?

    void Start () {
  
  ter.GetHeights();
    }
    
    // Update is called once per frame
    void Update () {
    
    }
}

using UnityEngine;
using System.Collections;

public class TerraiDeformer : MonoBehaviour
{

#region Public members
//This class member is used for Crater texture shape, you have to make sure that the access of the texture is Read/Write. You can find it in the advanced section of the import option when you select the texture.
public Texture2D CraterTexture;
// This class member modifies the intensity of the brush, if you don't introduce this factor, you will get harsh results, or you will not have a control over how hard your terrain is gonna be deformed
public float AlphaIntensity;
//Here you pass the terrain which you want to deform.
public Terrain targetTerrain;
#endregion

#region Private members
private float[,] SavedTerrainState { get; set; } // This class member is used to hold the original data of the terrain
private float[,] craterShape { get; set; } //Since the height map of the terrain is 2D array, and since we are modifying square area of the terrain, we are extracting the gray-scale information from our crater texture, and keeping it to modify the terrain.
// Texture info is a class I made in order to easily cache and manage the crater texture (brushes).
#endregion

void Start () {
// Remember, we are addressing a square map here, so you can imagine that 0,0 is the top left corner of the height map, and the terrain height map width and height are the maximum end points of the square

// Look at the constructor of the TextureInfo

}

void OnCollisionEnter(Collision _colObject)
{
// Here I'm deforming the terrain based on the position of the contact point. It could be a good idea to put a condition to make a certain object with a certain tag can modify the terrain, otherwise, anything which is colliding with the terrain will deform it.

}
void Update () {
if(Input.GetKeyDown(KeyCode.R))

SavedTerrainState = targetTerrain.terrainData.GetHeights(0, 0, targetTerrain.terrainData.heightmapWidth, targetTerrain.terrainData.heightmapHeight);

if(Input.GetKeyDown(KeyCode.E))
targetTerrain.terrainData.SetHeights(0, 0, SavedTerrainState);

}
}

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.Xml.Serialization;
using System.IO;
[System.Serializable]
public class Test {
       public float[,] SavedTerrainState { get; set; }
}
public class TerraiDeformer : MonoBehaviour
{

#region Public members
//This class member is used for Crater texture shape, you have to make sure that the access of the texture is Read/Write. You can find it in the advanced section of the import option when you select the texture.
public Texture2D CraterTexture;
// This class member modifies the intensity of the brush, if you don't introduce this factor, you will get harsh results, or you will not have a control over how hard your terrain is gonna be deformed
public float AlphaIntensity;
//Here you pass the terrain which you want to deform.
public Terrain targetTerrain;
#endregion

public float[,] SavedTerrainState { get; set; } // This class member is used to hold the original data of the terrain
private float[,] craterShape { get; set; } //Since the height map of the terrain is 2D array, and since we are modifying square area of the terrain, we are extracting the gray-scale information from our crater texture, and keeping it to modify the terrain.
// Texture info is a class I made in order to easily cache and manage the crater texture (brushes).

void Start () {
// Remember, we are addressing a square map here, so you can imagine that 0,0 is the top left corner of the height map, and the terrain height map width and height are the maximum end points of the square

// Look at the constructor of the TextureInfo

}

void OnCollisionEnter(Collision _colObject)
{
// Here I'm deforming the terrain based on the position of the contact point. It could be a good idea to put a condition to make a certain object with a certain tag can modify the terrain, otherwise, anything which is colliding with the terrain will deform it.

}
void Update () {
  if(Input.GetKeyDown(KeyCode.R))
  
                         SaveParams();
      
      if(Input.GetKeyDown(KeyCode.E))
                         LoadParams();

}

public void SaveParams(){
                var xml = new XmlSerializer (typeof(Test));
                var test = new Test ();

               
                test.SavedTerrainState = SavedTerrainState;

                using (var stream = new FileStream ("Test.xml", FileMode.Create, FileAccess.Write)) {
                        xml.Serialize (stream, test);
                }
  SavedTerrainState = targetTerrain.terrainData.GetHeights(0, 0, targetTerrain.terrainData.heightmapWidth, targetTerrain.terrainData.heightmapHeight);
                Debug.Log ("Объект сохранился");

        }
        public void LoadParams(){
                var xml = new XmlSerializer (typeof(Test));
                var test = new Test ();
                using (var stream = new FileStream ("Test.xml", FileMode.Open, FileAccess.Read)) {
                        test = xml.Deserialize (stream) as Test;
                }

                SavedTerrainState = test.SavedTerrainState;

targetTerrain.terrainData.SetHeights(0, 0, SavedTerrainState);
                Debug.Log ("Объект загружен");
        }

  
}

SavedTerrainState = targetTerrain.terrainData.GetHeights(0, 0, targetTerrain.terrainData.heightmapWidth, targetTerrain.terrainData.heightmapHeight);