최근 프로젝트에서 수어를 통역하는 기능을 구현해야 해서 MediaPipe를 사용하여 손의 LandMark를 추출해야 했다. 사실 필자도 코드를 완벽하게 이해하진 못했지만 기능을 성공적으로 구현했기에 어떻게 했는지 공유하고자 글을 쓴다.
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implementation 'com.google.mediapipe:solution-core:latest.release'
implementation 'com.google.mediapipe:hands:latest.release'
우선 app gradle 파일에 해당 코드를 추가하고 sync를 한다.
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<FrameLayout
android:id="@+id/preview_display_layout"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintTop_toBottomOf="@id/cl_voice"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintBottom_toTopOf="@id/cl_record">
</FrameLayout>
xml에 FrameLayout을 생성한다.
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/** A custom implementation of [ResultGlRenderer] to render [HandsResult]. */
class HandsResultGlRenderer : ResultGlRenderer<HandsResult?> {
private var program = 0
private var positionHandle = 0
private var projectionMatrixHandle = 0
private var colorHandle = 0
private fun loadShader(type: Int, shaderCode: String): Int {
val shader = GLES20.glCreateShader(type)
GLES20.glShaderSource(shader, shaderCode)
GLES20.glCompileShader(shader)
return shader
}
override fun setupRendering() {
program = GLES20.glCreateProgram()
val vertexShader = loadShader(GLES20.GL_VERTEX_SHADER, VERTEX_SHADER)
val fragmentShader = loadShader(GLES20.GL_FRAGMENT_SHADER, FRAGMENT_SHADER)
GLES20.glAttachShader(program, vertexShader)
GLES20.glAttachShader(program, fragmentShader)
GLES20.glLinkProgram(program)
positionHandle = GLES20.glGetAttribLocation(program, "vPosition")
projectionMatrixHandle = GLES20.glGetUniformLocation(program, "uProjectionMatrix")
colorHandle = GLES20.glGetUniformLocation(program, "uColor")
}
override fun renderResult(result: HandsResult?, projectionMatrix: FloatArray) {
if (result == null) {
return
}
GLES20.glUseProgram(program)
GLES20.glUniformMatrix4fv(projectionMatrixHandle, 1, false, projectionMatrix, 0)
GLES20.glLineWidth(CONNECTION_THICKNESS)
val numHands = result.multiHandLandmarks().size
for (i in 0 until numHands) {
val isLeftHand = result.multiHandedness()[i].label == "Left"
drawConnections(
result.multiHandLandmarks()[i].landmarkList,
if (isLeftHand) LEFT_HAND_CONNECTION_COLOR else RIGHT_HAND_CONNECTION_COLOR
)
for(ind in result.multiHandLandmarks()[i].landmarkList.indices) {
val lm = result.multiHandLandmarks()[i].landmarkList[ind]
Log.d(TAG, "LandMark[$ind] | x : ${lm.x}, y : ${lm.y}, z : ${lm.z}")
}
for (landmark in result.multiHandLandmarks()[i].landmarkList) {
// Draws the landmark.
drawCircle(
landmark.x,
landmark.y,
if (isLeftHand) LEFT_HAND_LANDMARK_COLOR else RIGHT_HAND_LANDMARK_COLOR
)
//Log.d(TAG, "LandMark | x : ${landmark.x}, y : ${landmark.y}, z : ${landmark.z}")
// Draws a hollow circle around the landmark.
drawHollowCircle(
landmark.x,
landmark.y,
if (isLeftHand) LEFT_HAND_HOLLOW_CIRCLE_COLOR
else RIGHT_HAND_HOLLOW_CIRCLE_COLOR
)
}
}
}
/**
* Deletes the shader program.
*
*
* This is only necessary if one wants to release the program
while keeping the context around.
*/
fun release() {
GLES20.glDeleteProgram(program)
}
private fun drawConnections(
handLandmarkList: List<NormalizedLandmark>,
colorArray: FloatArray
) {
GLES20.glUniform4fv(colorHandle, 1, colorArray, 0)
for (c in Hands.HAND_CONNECTIONS) {
val start = handLandmarkList[c.start()]
val end = handLandmarkList[c.end()]
val vertex = floatArrayOf(start.x, start.y, end.x, end.y)
val vertexBuffer = ByteBuffer.allocateDirect(vertex.size * 4)
.order(ByteOrder.nativeOrder())
.asFloatBuffer()
.put(vertex)
vertexBuffer.position(0)
GLES20.glEnableVertexAttribArray(positionHandle)
GLES20.glVertexAttribPointer(positionHandle, 2, GLES20.GL_FLOAT,
false, 0, vertexBuffer)
GLES20.glDrawArrays(GLES20.GL_LINES, 0, 2)
}
}
private fun drawCircle(x: Float, y: Float, colorArray: FloatArray) {
GLES20.glUniform4fv(colorHandle, 1, colorArray, 0)
val vertexCount = NUM_SEGMENTS + 2
val vertices = FloatArray(vertexCount * 3)
vertices[0] = x
vertices[1] = y
vertices[2] = 0f
for (i in 1 until vertexCount) {
val angle = 2.0f * i * Math.PI.toFloat() / NUM_SEGMENTS
val currentIndex = 3 * i
vertices[currentIndex] = x + (LANDMARK_RADIUS * Math.cos(angle.toDouble())).toFloat()
vertices[currentIndex + 1] =
y + (LANDMARK_RADIUS * Math.sin(angle.toDouble())).toFloat()
vertices[currentIndex + 2] = 0f
}
val vertexBuffer = ByteBuffer.allocateDirect(vertices.size * 4)
.order(ByteOrder.nativeOrder())
.asFloatBuffer()
.put(vertices)
vertexBuffer.position(0)
GLES20.glEnableVertexAttribArray(positionHandle)
GLES20.glVertexAttribPointer(positionHandle, 3, GLES20.GL_FLOAT,
false, 0, vertexBuffer)
GLES20.glDrawArrays(GLES20.GL_TRIANGLE_FAN, 0, vertexCount)
}
private fun drawHollowCircle(x: Float, y: Float, colorArray: FloatArray) {
GLES20.glUniform4fv(colorHandle, 1, colorArray, 0)
val vertexCount = NUM_SEGMENTS + 1
val vertices = FloatArray(vertexCount * 3)
for (i in 0 until vertexCount) {
val angle = 2.0f * i * Math.PI.toFloat() / NUM_SEGMENTS
val currentIndex = 3 * i
vertices[currentIndex] =
x + (HOLLOW_CIRCLE_RADIUS * Math.cos(angle.toDouble())).toFloat()
vertices[currentIndex + 1] =
y + (HOLLOW_CIRCLE_RADIUS * Math.sin(angle.toDouble())).toFloat()
vertices[currentIndex + 2] = 0f
}
val vertexBuffer = ByteBuffer.allocateDirect(vertices.size * 4)
.order(ByteOrder.nativeOrder())
.asFloatBuffer()
.put(vertices)
vertexBuffer.position(0)
GLES20.glEnableVertexAttribArray(positionHandle)
GLES20.glVertexAttribPointer(positionHandle, 3, GLES20.GL_FLOAT,
false, 0, vertexBuffer)
GLES20.glDrawArrays(GLES20.GL_LINE_STRIP, 0, vertexCount)
}
companion object {
private const val TAG = "HandsResultGlRenderer"
private val LEFT_HAND_CONNECTION_COLOR = floatArrayOf(0.2f, 1f, 0.2f, 1f)
private val RIGHT_HAND_CONNECTION_COLOR = floatArrayOf(1f, 0.2f, 0.2f, 1f)
private const val CONNECTION_THICKNESS = 25.0f
private val LEFT_HAND_HOLLOW_CIRCLE_COLOR = floatArrayOf(0.2f, 1f, 0.2f, 1f)
private val RIGHT_HAND_HOLLOW_CIRCLE_COLOR = floatArrayOf(1f, 0.2f, 0.2f, 1f)
private const val HOLLOW_CIRCLE_RADIUS = 0.01f
private val LEFT_HAND_LANDMARK_COLOR = floatArrayOf(1f, 0.2f, 0.2f, 1f)
private val RIGHT_HAND_LANDMARK_COLOR = floatArrayOf(0.2f, 1f, 0.2f, 1f)
private const val LANDMARK_RADIUS = 0.008f
private const val NUM_SEGMENTS = 120
private const val VERTEX_SHADER = ("uniform mat4 uProjectionMatrix;\n"
+ "attribute vec4 vPosition;\n"
+ "void main() {\n"
+ " gl_Position = uProjectionMatrix * vPosition;\n"
+ "}")
private const val FRAGMENT_SHADER = ("precision mediump float;\n"
+ "uniform vec4 uColor;\n"
+ "void main() {\n"
+ " gl_FragColor = uColor;\n"
+ "}")
}
}
HandsResultGlRenderer 클래스를 생성한다. 만약 LandMark를 화면에 띄우는걸 원하지 않는다면 drawConnections 함수, drawCircle 함수, drawHollowCircle 함수를 지우고 renderResult 함수 내에 방금 3가지 함수를 지우면 된다.
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<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
Manifest에 해당 권한들을 추가한다.
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private lateinit var hands : Hands
private lateinit var cameraInput: CameraInput
private lateinit var glSurfaceView: SolutionGlSurfaceView<HandsResult>
private val REQUIRED_PERMISSIONS = mutableListOf(Manifest.permission.INTERNET,
Manifest.permission.RECORD_AUDIO, Manifest.permission.CAMERA,
Manifest.permission.ACCESS_NETWORK_STATE).toTypedArray()
전역 변수로 필요한 변수들을 선언한다.
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val permissionListener = object: PermissionListener {
override fun onPermissionGranted() {
setupStreamingModePipeline()
glSurfaceView.post { startCamera() }
glSurfaceView.visibility = View.VISIBLE
initView()
}
override fun onPermissionDenied(deniedPermissions: MutableList<String>?) {
Toast.makeText(requireContext(), "권한을 다시 설정해주세요!", Toast.LENGTH_SHORT).show()
}
}
TedPermission.create()
.setPermissionListener(permissionListener)
.setPermissions(*REQUIRED_PERMISSIONS)
.check()
권한이 모두 허용이 되었다면 onCreate에 셋팅을 해준다.
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private fun setupStreamingModePipeline() {
hands = Hands(
this@MainActivity,
HandsOptions.builder()
.setStaticImageMode(false)
.setMaxNumHands(1)
.setRunOnGpu(true)
.build()
)
hands.setErrorListener { message, e -> Log.e("TAG", "MediaPipe Hands error: $message") }
cameraInput = CameraInput(this@MainActivity)
cameraInput.setNewFrameListener { hands.send(it) }
glSurfaceView = SolutionGlSurfaceView(this@MainActivity, hands.glContext,
hands.glMajorVersion)
glSurfaceView.setSolutionResultRenderer(HandsResultGlRenderer())
glSurfaceView.setRenderInputImage(true)
hands.setResultListener {
glSurfaceView.setRenderData(it)
glSurfaceView.requestRender()
}
glSurfaceView.post(this::startCamera)
// activity_main.xml에 선언한 FrameLayout에 화면을 띄우는 코드
binding.previewDisplayLayout.apply {
removeAllViewsInLayout()
addView(glSurfaceView)
glSurfaceView.visibility = View.VISIBLE
requestLayout()
}
}
private fun startCamera() {
cameraInput.start(
this@MainActivity,
hands.glContext,
CameraInput.CameraFacing.FRONT,
glSurfaceView.width,
glSurfaceView.height
)
}
이렇게 하면 성공적으로 FrameLayout에 자신의 손을 실시간으로 인식하는 영상을 볼 수 있을 것이다. 코드를 이해해가면서 작성하는 것을 추구하지만 프로젝트를 하면서 기능 구현할 시간이 많지 않았기에 해당 코드를 완벽하게 이해하진 못했다. 
Log에는 손의 21개 LandMark들의 x,y,z 값을 확인할 수 있다.
손 말고 얼굴 인식도 아래 코드를 참고해서 하면 될 것 같다. Mediapipe Github 참고자료