经纬度转化成Unity中的世界坐标

最近项目中用到了把现实中的经纬度转化成Unity中的坐标。
下面是代码：

public class GisPointTo3DPoint : MonoBehaviour
{

    public static GisPointTo3DPoint Instance = null;
    public Transform BottomRightPoint; //Unity中右下点  （X正方向和Z轴的负方向之间）
    public Transform TopLeftPoint;//Unity中左上点  （Z轴正方向和X轴负方向之间）

    private Vector2 BottomRightSai;//地图中对应的左上经纬度点  
    private Vector2 TopLeftSai;//地图中对应的右下经纬度点  

    private float z_offset, x_offset, z_w_offset, x_w_offset;

    private RaycastHit rayHit;

    private void Awake()
    {            
        if (Instance == null) Instance = this;
        else if (Instance != this) Destroy(this);
        InitBasicNum();//初始化参数 
    }

    private void InitBasicNum()
    {
        //通过传过来的第一个点，确定坐标范围。以导弹为中心
        //右下
        BottomRightSai = new Vector2(103.41247f, 24.49035f);
        //左上
        TopLeftSai = new Vector2(103.35547f, 24.5241f);
        z_offset = 24.49035f - 24.5241f;
        x_offset = 103.41247f - 103.35547f;
        //z_offset = BottomRightSai.y - TopLeftSai.y;//地图中的维度差  
       // x_offset = BottomRightSai.x - TopLeftSai.x;//地图中的经度差  
        z_w_offset = BottomRightPoint.position.z - TopLeftPoint.position.z;//unity中的维度差  
        x_w_offset = BottomRightPoint.position.x - TopLeftPoint.position.x;//unity中的经度差  
    }
    /// 

    /// 由经纬度得到位置点  
    /// 
    /// x经度
    /// y 纬度
    /// 
    public Vector3 GetWorldPoint(float x, float y)
    {
        float tempX = x - 103.35547f;//TopLeftSai.x;
        float tempZ = y - 24.49035f; //BottomRightSai.y;
        float _tempX = (tempX * x_w_offset / x_offset + TopLeftPoint.position.x);
        float _tempZ = (tempZ * z_w_offset / z_offset + BottomRightPoint.position.z);
        //坐标偏差
        return new Vector3(_tempX, 0, _tempZ);
    }
    /// 

    /// 由位置点得到经纬度  
    /// 
    /// 
    /// 
    public Vector3 GetLatLon(Vector3 curPoint)
    {
        //坐标偏差
        float _x_offset = (curPoint.x - BottomRightPoint.position.x) * x_offset / x_w_offset;
        float _z_offset = (curPoint.z - TopLeftPoint.position.z) * z_offset / z_w_offset;
        float resultX = _x_offset + BottomRightSai.x;
        float resultZ = _z_offset + TopLeftSai.y;
        return new Vector2(resultX, resultZ);
    }
}