(1) 问题描述

OpenPose可以解决多人骨骼、手势、面部实时识别的问题。本项目是OpenPose获取的数据在Unity3D中的一个实现，可将解析出来的坐标数据在Unity中进行调用，实现Unity模型的随动控制。

(2) OpenPose的安装

请参考：
Win10的VS17/15环境下OpenPose的安装部署，以及一些经验分享
https://blog.csdn.net/BenJamin_Blue/article/details/84574750

(3) JSON数据的解析

对OpenPose结果保留的源码做如图所示处理，即可获得JSON格式的节点坐标数据。

其中框选位置为JSON数据的保存路径。

数据的解析过程请参考：
JSON数据的Unity3D解析过程
https://blog.csdn.net/BenJamin_Blue/article/details/86565510
代码如下：

using UnityEngine;
using System;
using System.Collections;
using System.Linq;
using System.Text;
using System.Collections.Generic;

[Serializable]
public class ModelTest
{
    public float version;
    public List<People_sets> people;
}

[Serializable]
public class People_sets
{
    public float[] pose_keypoints_2d;
 //   public float[] hand_left_keypoints_2d;
 //   public float[] hand_right_keypoints_2d;
}

using UnityEngine;
using System.IO;
using System.Text;
using System;
using System.Collections;
using System.Linq;
using System.Collections.Generic;

public class JsonTest : MonoBehaviour
{
    static public float[] pose_joint_x = new float[20];
    static public float[] pose_joint_y = new float[20];

    int num = 0;

    // Use this for initialization
    void Start()
    {

    }

    // Update is called once per frame
    void Update()
    {
        try
        {
            num += 1;

            //get the last file name
            string numString = Convert.ToString(num);
            string zero = "";
            string pathBefore = "/Resources/OpenPose/";
            for (int j = 0; j < (12 - numString.Length); j++)
            {
                zero = zero + "0";
            }
            Debug.Log(pathBefore + zero + numString + "_keypoints.json");

            //analysis data from json
            string jsonTest = File.ReadAllText(Application.dataPath + pathBefore + zero + numString + "_keypoints.json", Encoding.UTF8);
            ModelTest obj = JsonUtility.FromJson<ModelTest>(jsonTest);

            //pervent joints return to (0,0,0)
            for (int i = 0; i < 18; i++)
            {
                if (obj.people[0].pose_keypoints_2d[3 * i] == 0.0f)
                {

                }
                else
                {
                    pose_joint_x[i] = obj.people[0].pose_keypoints_2d[3 * i];
                }

                if (obj.people[0].pose_keypoints_2d[3 * i + 1] == 0.0f)
                {

                }
                else
                {
                    pose_joint_y[i] = obj.people[0].pose_keypoints_2d[3 * i + 1];
                }
            }
        }
        catch (ArgumentOutOfRangeException)
        {

        }

        //stay if file doesn't reach the num
        catch (FileNotFoundException)
        {
            num = num - 1;
        }
    }
}

(4) 人物点线模型的构建&节点的运动

请参考：
Unity3D人体18节点骨骼动态简单点线模型的建立
https://blog.csdn.net/BenJamin_Blue/article/details/86566015
代码如下：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.Threading;

public class MoveJoints : MonoBehaviour
{
    #region definition
    
    public float speed = 5f;
    //线段渲染器*4  
    private LineRenderer lineRenderer1;
    private LineRenderer lineRenderer2;
    private LineRenderer lineRenderer3;
    private LineRenderer lineRenderer4;

    private int lineLength = 300;

    GameObject LEar16;
    GameObject LEye14;
    GameObject MNose0;
    GameObject REye15;
    GameObject REar17;
    GameObject MMid1;
    GameObject LShoulder2;
    GameObject RShoulder5;
    GameObject LElbow3;
    GameObject RElbow6;
    GameObject LWrist4;
    GameObject RWrist7;
    GameObject LAss8;
    GameObject RAss11;
    GameObject LKnee9;
    GameObject RKnee12;
    GameObject LFoot10;
    GameObject RFoot13;

    #endregion

    //将场景的物体关联到该脚本中
    void InitObject()
    {
        LEar16 = GameObject.Find("LEar16");
        LEye14 = GameObject.Find("LEye14");
        MNose0 = GameObject.Find("MNose0");
        REye15 = GameObject.Find("REye15");
        REar17 = GameObject.Find("REar17");
        MMid1 = GameObject.Find("MMid1");
        LShoulder2 = GameObject.Find("LShoulder2");
        RShoulder5 = GameObject.Find("RShoulder5");
        LElbow3 = GameObject.Find("LElbow3");
        RElbow6 = GameObject.Find("RElbow6");
        LWrist4 = GameObject.Find("LWrist4");
        RWrist7 = GameObject.Find("RWrist7");
        LAss8 = GameObject.Find("LAss8");
        RAss11 = GameObject.Find("RAss11");
        LKnee9 = GameObject.Find("LKnee9");
        RKnee12 = GameObject.Find("RKnee12");
        LFoot10 = GameObject.Find("LFoot10");
        RFoot13 = GameObject.Find("RFoot13");

     //   Line1 = GameObject.Find("Line1");

        lineRenderer1 = (LineRenderer)MNose0.GetComponent("LineRenderer");
        lineRenderer2 = (LineRenderer)MMid1.GetComponent("LineRenderer");
        lineRenderer3 = (LineRenderer)LShoulder2.GetComponent("LineRenderer");
        lineRenderer4 = (LineRenderer)LElbow3.GetComponent("LineRenderer");
    }

    // Use this for initialization
    void Start()
    {
        InitObject();
        lineRenderer1.positionCount = lineLength;
        lineRenderer2.positionCount = lineLength;
        lineRenderer3.positionCount = lineLength;
        lineRenderer4.positionCount = lineLength;

        lineRenderer1.positionCount = 7;
        lineRenderer2.positionCount = 7;
        lineRenderer3.positionCount = 4;
        lineRenderer4.positionCount = 4;
    }

    // Update is called once per frame

    void Update()
    {
        float step = speed * Time.deltaTime;
        //move joints using interpolation method
        LEar16.transform.localPosition = new Vector3(Mathf.Lerp(LEar16.transform.localPosition.x, 0.1f * JsonTest.pose_joint_x[16], step), Mathf.Lerp(LEar16.transform.localPosition.y, -0.1f * JsonTest.pose_joint_y[16], step), 0);
        MNose0.transform.localPosition = new Vector3(Mathf.Lerp(MNose0.transform.localPosition.x, 0.1f * JsonTest.pose_joint_x[0], step), Mathf.Lerp(MNose0.transform.localPosition.y, -0.1f * JsonTest.pose_joint_y[0], step), 0);
        LEye14.transform.localPosition = new Vector3(Mathf.Lerp(LEye14.transform.localPosition.x, 0.1f * JsonTest.pose_joint_x[14], step), Mathf.Lerp(LEye14.transform.localPosition.y, -0.1f * JsonTest.pose_joint_y[14], step), 0);
        REye15.transform.localPosition = new Vector3(Mathf.Lerp(REye15.transform.localPosition.x, 0.1f * JsonTest.pose_joint_x[15], step), Mathf.Lerp(REye15.transform.localPosition.y, -0.1f * JsonTest.pose_joint_y[15], step), 0);
        MMid1.transform.localPosition = new Vector3(Mathf.Lerp(MMid1.transform.localPosition.x, 0.1f * JsonTest.pose_joint_x[1], step), Mathf.Lerp(MMid1.transform.localPosition.y, -0.1f * JsonTest.pose_joint_y[1], step), 0);
        LShoulder2.transform.localPosition = new Vector3(Mathf.Lerp(LShoulder2.transform.localPosition.x, 0.1f * JsonTest.pose_joint_x[2], step), Mathf.Lerp(LShoulder2.transform.localPosition.y, -0.1f * JsonTest.pose_joint_y[2], step), 0);
        RShoulder5.transform.localPosition = new Vector3(Mathf.Lerp(RShoulder5.transform.localPosition.x, 0.1f * JsonTest.pose_joint_x[5], step), Mathf.Lerp(RShoulder5.transform.localPosition.y, -0.1f * JsonTest.pose_joint_y[5], step), 0);
        LElbow3.transform.localPosition = new Vector3(Mathf.Lerp(LElbow3.transform.localPosition.x, 0.1f * JsonTest.pose_joint_x[3], step), Mathf.Lerp(LElbow3.transform.localPosition.y, -0.1f * JsonTest.pose_joint_y[3], step), 0);
        RElbow6.transform.localPosition = new Vector3(Mathf.Lerp(RElbow6.transform.localPosition.x, 0.1f * JsonTest.pose_joint_x[6], step), Mathf.Lerp(RElbow6.transform.localPosition.y, -0.1f * JsonTest.pose_joint_y[6], step), 0);
        LWrist4.transform.localPosition = new Vector3(Mathf.Lerp(LWrist4.transform.localPosition.x, 0.1f * JsonTest.pose_joint_x[4], step), Mathf.Lerp(LWrist4.transform.localPosition.y, -0.1f * JsonTest.pose_joint_y[4], step), 0);
        RWrist7.transform.localPosition = new Vector3(Mathf.Lerp(RWrist7.transform.localPosition.x, 0.1f * JsonTest.pose_joint_x[7], step), Mathf.Lerp(RWrist7.transform.localPosition.y, -0.1f * JsonTest.pose_joint_y[7], step), 0);
        LAss8.transform.localPosition = new Vector3(Mathf.Lerp(LAss8.transform.localPosition.x, 0.1f * JsonTest.pose_joint_x[8], step), Mathf.Lerp(LAss8.transform.localPosition.y, -0.1f * JsonTest.pose_joint_y[8], step), 0);
        RAss11.transform.localPosition = new Vector3(Mathf.Lerp(RAss11.transform.localPosition.x, 0.1f * JsonTest.pose_joint_x[11], step), Mathf.Lerp(RAss11.transform.localPosition.y, -0.1f * JsonTest.pose_joint_y[11], step), 0);
        LKnee9.transform.localPosition = new Vector3(Mathf.Lerp(LKnee9.transform.localPosition.x, 0.1f * JsonTest.pose_joint_x[9], step), Mathf.Lerp(LKnee9.transform.localPosition.y, -0.1f * JsonTest.pose_joint_y[9], step), 0);
        RKnee12.transform.localPosition = new Vector3(Mathf.Lerp(RKnee12.transform.localPosition.x, 0.1f * JsonTest.pose_joint_x[12], step), Mathf.Lerp(RKnee12.transform.localPosition.y, -0.1f * JsonTest.pose_joint_y[12], step), 0);
        LFoot10.transform.localPosition = new Vector3(Mathf.Lerp(LFoot10.transform.localPosition.x, 0.1f * JsonTest.pose_joint_x[10], step), Mathf.Lerp(LFoot10.transform.localPosition.y, -0.1f * JsonTest.pose_joint_y[10], step), 0);
        RFoot13.transform.localPosition = new Vector3(Mathf.Lerp(RFoot13.transform.localPosition.x, 0.1f * JsonTest.pose_joint_x[13], step), Mathf.Lerp(RFoot13.transform.localPosition.y, -0.1f * JsonTest.pose_joint_y[13], step), 0);
        REar17.transform.localPosition = new Vector3(Mathf.Lerp(REar17.transform.localPosition.x, 0.1f * JsonTest.pose_joint_x[17], step), Mathf.Lerp(REar17.transform.localPosition.y, -0.1f * JsonTest.pose_joint_y[17], step), 0);

        //it requires 4 lines to connect all the joints
        lineRenderer1.SetPosition(0, LEar16.transform.localPosition);
        lineRenderer1.SetPosition(1, LEye14.transform.localPosition);
        lineRenderer1.SetPosition(2, MNose0.transform.localPosition);
        lineRenderer1.SetPosition(3, MMid1.transform.localPosition);
        lineRenderer1.SetPosition(4, LShoulder2.transform.localPosition);
        lineRenderer1.SetPosition(5, LElbow3.transform.localPosition);
        lineRenderer1.SetPosition(6, LWrist4.transform.localPosition);

        lineRenderer2.SetPosition(0, REar17.transform.localPosition);
        lineRenderer2.SetPosition(1, REye15.transform.localPosition);
        lineRenderer2.SetPosition(2, MNose0.transform.localPosition);
        lineRenderer2.SetPosition(3, MMid1.transform.localPosition);
        lineRenderer2.SetPosition(4, RShoulder5.transform.localPosition);
        lineRenderer2.SetPosition(5, RElbow6.transform.localPosition);
        lineRenderer2.SetPosition(6, RWrist7.transform.localPosition);

        lineRenderer3.SetPosition(0, LFoot10.transform.localPosition);
        lineRenderer3.SetPosition(1, LKnee9.transform.localPosition);
        lineRenderer3.SetPosition(2, LAss8.transform.localPosition);
        lineRenderer3.SetPosition(3, MMid1.transform.localPosition);

        lineRenderer4.SetPosition(0, RFoot13.transform.localPosition);
        lineRenderer4.SetPosition(1, RKnee12.transform.localPosition);
        lineRenderer4.SetPosition(2, RAss11.transform.localPosition);
        lineRenderer4.SetPosition(3, MMid1.transform.localPosition);
    }
}

(5) 运行结果

如图所示，该工作可以将OpenPose采集的节点数据实时传递给Unity的模型。

(6) 局限性分析

由于一般的网络摄像头无法获取景深信息，在多人识别的情况下，OpenPose只能输出为2D坐标；但若开启OpenPose的深度测量模式（如图所示），除了需要必要的深度相机外、仅限对于单个对象的识别。

由于笔者认识有限，姑且认为目前目前没有针对多人3D识别的有效开源项目。若有更好的方案，还请诸位给予转告，笔者在此谢过。