unity读取灰度图生成等值线图

准备灰度图 grayTest.png，放置于Assets下StreamingAssets文件夹中。

 

在场景中添加RawImage用于显示最后的等值线图。

 

生成等值线的过程，使用Marching squares中Isolines方式。

https://en.wikipedia.org/wiki/Marching_squares

 

首先将顶点数据与阈值比较，对顶点进行标记。根据四个顶点的标记情况，连接各个线段的中点，组成等值线。

 

测试中在texture2d对线段中点进行涂色以显示。

 

脚本如下：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

//生成等值线图
public class IsoLinesCreate : MonoBehaviour {
    private Texture2D importImage;//输入灰度图
    private Texture grayImage;//加载灰度图
    private Texture2D outputImage;//输出等值线图
    private bool bCreate=false;
    [Tooltip("用作显示输出的等高线图")]
    public RawImage showImage;
    private int tGrayWidth = 0, tGrayHeight = 0;//灰度图的宽和高
    void Start () {
        StartCoroutine(loadImage("grayTest.png", (t) => grayImage = t));
    } 
 
	void Update () {
        if (grayImage!=null)
        {
            if (bCreate==false)
            {
                importImage = (Texture2D)grayImage;
                outputImage = (Texture2D)grayImage;
                tGrayWidth = grayImage.width;
                tGrayHeight = grayImage.height;
                showImage.rectTransform.sizeDelta = new Vector2(tGrayWidth,tGrayHeight);

                //测试不同阈值不同颜色等值线绘制
                trackIsoline(0.5f,Color.blue,2);
                trackIsoline(0.6f, Color.green, 2);
                trackIsoline(0.7f, Color.yellow, 2);
                trackIsoline(0.8f, Color.red, 2);

                showImage.texture = outputImage;
                bCreate = true;
            }
        }
	}

    //加载图片
    IEnumerator loadImage(string imagePath, System.Action<Texture> action)
    {
        WWW www = new WWW("file://" + Application.streamingAssetsPath + "/" + imagePath);
        yield return www;
        if (www.error == null)
        {
            action(www.texture);
        }
    }

   
    /// <summary>
    /// 等值线追踪
    /// </summary>
    /// <param name="threshold">灰度阈值</param>
    /// <param name="colorP">颜色</param>
    /// <param name="step">步长 为偶数</param>
    private void trackIsoline(float threshold,Color colorP,int step)
    {
        for (int i = 0; i < tGrayWidth-step; i+=step)
        {
            for (int j = 0; j < tGrayHeight-step; j+=step)
            {
                //标记顶点状态
                int tempCount = 0;//0000
                if (importImage.GetPixel(i,j).grayscale>threshold)
                {
                    tempCount += 1;//0001
                }
                if (importImage.GetPixel(i+step, j).grayscale > threshold)
                {
                    tempCount += 8;//1000
                }
                if (importImage.GetPixel(i+step, j+step).grayscale > threshold)
                {
                    tempCount += 4;//0100
                }
                if (importImage.GetPixel(i, j+step).grayscale > threshold)
                {
                    tempCount += 2;//0010
                }
                int t = step / 2;
                //根据顶点标记情况处理中点连线（此处对中点进行上色）
                switch (tempCount)
                {
                    case 0:
                    case 15:
                        break;
                    case 1:
                    case 14:
                        outputImage.SetPixel(i+t,j,colorP);
                        outputImage.SetPixel(i,j+t,colorP);
                        break;
                    case 2:
                    case 13:
                        outputImage.SetPixel(i , j+t, colorP);
                        outputImage.SetPixel(i+t, j + 2*t, colorP);
                        break;
                    case 3:
                    case 12:
                        outputImage.SetPixel(i+t, j, colorP);
                        outputImage.SetPixel(i + t, j + 2 * t, colorP);
                        break;
                    case 4:
                    case 11:
                        outputImage.SetPixel(i +2* t, j+t, colorP);
                        outputImage.SetPixel(i + t, j + 2 * t, colorP);
                        break;
                    case 5:
                        outputImage.SetPixel(i + t, j, colorP);
                        outputImage.SetPixel(i + 2*t, j +  t, colorP);

                        outputImage.SetPixel(i , j + t, colorP);
                        outputImage.SetPixel(i + t, j + 2 * t, colorP);
                        break;
                    case 6:
                    case 9:
                        outputImage.SetPixel(i, j + t, colorP);
                        outputImage.SetPixel(i +2* t, j + t, colorP);
                        break;
                    case 7:
                    case 8:
                        outputImage.SetPixel(i+t, j, colorP);
                        outputImage.SetPixel(i + 2 * t, j + t, colorP);
                        break; 
                    case 10:
                        outputImage.SetPixel(i + t, j, colorP);
                        outputImage.SetPixel(i, j + t, colorP);

                        outputImage.SetPixel(i + 2*t, j+t, colorP);
                        outputImage.SetPixel(i + t, j + 2*t, colorP);
                        break; 
                }  
            }
        } 
        outputImage.Apply();
    }
}

 本文链接 https://www.cnblogs.com/gucheng/p/10107696.html