# Problem with Perlin Noise on negative coordinates

Hey guys!
First time here, so sorry for being a greenhorn.
I have created a simple game in Unity wich generates Terrain procedurally and uses a simple form of chunck loading.
Here’s some pictures:
![alt text]
![alt text]
But, there is a problem. The generated terrain is based on Perlin Noise. When I get to the World-Coordinates x = 0 or z = 0 (Even though I have Shifting Origin, those coordinates are the absoulte ones!) the terrain is basically mirrored:
![alt text]
What can I do against that? Looking forward to answers! Here is the code:

``````using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class ProceduralTerrain : MonoBehaviour {
int id;
Mesh mesh;
Vector3[] vertices;
Vector3[] normals;

Vector2 old_tile_coordinate = new Vector2(10,10);
// Use this for initialization
void Start () {

for (int i = 0; i < 26; i++)
{
if (name == TileManager.tile*.name)*
``````

{
id = i;
}
}

//RecalculateTerrain();
}

public void RecalculateTerrain()
{

mesh = GetComponent().mesh;
vertices = mesh.vertices;
normals = mesh.normals;

for (int i = 0; i < vertices.Length; i++)
{
float real_x = (float)TileManager.tile_coordinate[id].x * 100.0f + vertices_.x * 10.0f;
float real_z = (float)TileManager.tile_coordinate[id].y * 100.0f + vertices.z * 10.0f;_

float height = (Mathf.PerlinNoise(real_x * 0.003f * Mathf.PI, real_z * 0.003f * Mathf.PI) - 0.5f) * 5.0f;

vertices*.y = height;*

}
mesh.vertices = vertices;
mesh.RecalculateBounds();
mesh.RecalculateNormals();

GetComponent().sharedMesh = null;
GetComponent().sharedMesh = mesh;
}

* // Update is called once per frame*
* void Update () {*
if (old_tile_coordinate != TileManager.tile_coordinate[id])
{
RecalculateTerrain();
}
old_tile_coordinate = TileManager.tile_coordinate[id];
* }*
}
*: http://i.imgur.com/mWbpvOw.jpg*_
: http://i.imgur.com/pjzyUUB.jpg*_
_: http://i.imgur.com/AVsZZPJ.jpg*_

4 years later Perlin noise is mirrored around zero coordinates. Use extra octaves to blend it in and hopefully hide it.

In case it is not inifite terrain you can just add some big fixed number to your coordinates when generating through perlin