我将为您创建一个手掌旋转的视频特效，使用计算机视觉技术检测手掌并进行动态旋转。

实现思路

1. 使用MediaPipe检测手掌关键点

2. 计算手掌方向和旋转角度

3. 创建旋转动画效果

4. 将特效应用到实时视频流

完整代码

python

import cv2

import numpy as np

import mediapipe as mp

from scipy.spatial.transform import Rotation as R

class PalmRotationEffect:

def __init__(self):

# 初始化MediaPipe Hands

self.mp_hands = mp.solutions.hands

self.hands = self.mp_hands.Hands(

static_image_mode=False,

max_num_hands=1,

min_detection_confidence=0.7,

min_tracking_confidence=0.7

self.mp_drawing = mp.solutions.drawing_utils

def detect_palm_orientation(self, landmarks):

计算手掌方向和旋转角度

# 使用手掌关键点计算方向向量

wrist = landmarks[0] # 手腕

middle_mcp = landmarks[9] # 中指根部

# 计算手掌方向向量

direction_vector = np.array([

middle_mcp.x

middle_mcp.y

middle_mcp.z

] ])

# 归一化

norm = np.linalg.norm(direction_vector)

if norm > 0:

direction_vector /= norm

return direction_vector

def calculate_rotation_matrix(self, direction_vector, rotation_angle):

根据手掌方向和附加旋转角度计算旋转矩阵

# 基础旋转矩阵（基于手掌方向）

target_dir = np.array([0, -1, 0]) # 目标方向（向上）

if np.linalg.norm(np.cross(direction_vector, target_dir)) > 1e-6:

rotation_axis = np.cross(direction_vector, target_dir)

rotation_axis = rotation_axis / np.linalg.norm(rotation_axis)

# 计算基础旋转角度

dot_product = np.dot(direction_vector, target_dir)

base_angle = np.arccos(np.clip(dot_product, -1.0, 1.0))

# 添加额外旋转角度

total_angle = base_angle + np.radians(rotation_angle)

# 创建旋转对象

rotation = R.from_rotvec(total_angle * rotation_axis)

return rotation.as_matrix

return np.eye(3) # 返回单位矩阵

def create_palm_mask(self, frame, landmarks):

创建手掌区域的遮罩

h, w = frame.shape[:2]

mask = np.zeros((h, w), dtype=np.uint8)

# 手掌轮廓点索引（简化版本）

palm_points = [0, 1, 5, 9, 13, 17, 0]

points = []

for idx in palm_points:

landmark = landmarks[idx]

x, y = int(landmark.x * w), int(landmark.y * h)

points.append([x, y])

# 填充手掌区域

if len(points) > 2:

cv2.fillPoly(mask, [np.array(points)], 255)

return mask

def apply_rotation_effect(self, frame, landmarks, rotation_angle=0):

应用旋转特效到检测到的手掌

h, w = frame.shape[:2]

# 创建手掌遮罩

mask = self.create_palm_mask(frame, landmarks)

# 计算手掌方向

direction_vector = self.detect_palm_orientation(landmarks)

# 计算旋转矩阵

rotation_matrix = self.calculate_rotation_matrix(direction_vector, rotation_angle)

# 应用旋转到手掌区域

result_frame = frame.copy

# 找到手掌边界框

coords = np.where(mask == 255)

if len(coords[0]) > 0 and len(coords[1]) > 0:

y_min, y_max = np.min(coords[0]), np.max(coords[0])

x_min, x_max = np.min(coords[1]), np.max(coords[1])

# 提取手掌区域

palm_region = frame[y_min:y_max+1, x_min:x_max+1].copy

if palm_region.size > 0:

# 对区域应用透视变换模拟旋转

center_x, center_y = (x_min + x_max) // 2, (y_min + y_max) // 2

# 创建变换矩阵

scale = 1.2

angle_rad = np.radians(rotation_angle)

# 旋转矩阵

M = cv2.getRotationMatrix2D((palm_region.shape[1]//2, palm_region.shape[0]//2),

rotation_angle, scale)

# 应用旋转变换

rotated_palm = cv2.warpAffine(palm_region, M,

(palm_region.shape[1], palm_region.shape[0]))

# 创建旋转后的遮罩

rotated_mask = cv2.warpAffine(mask[y_min:y_max+1, x_min:x_max+1], M,

(palm_region.shape[1], palm_region.shape[0]))

# 将旋转后的手掌合成到原图

for i in range(rotated_palm.shape[0]):

for j in range(rotated_palm.shape[1]):

global_y = y_min + i

global_x = x_min + j

if (0

rotated_mask[i, j] > 128):

result_frame[global_y, global_x] = rotated_palm[i, j]

return result_frame

def process_frame(self, frame, rotation_angle=0):

处理单帧图像

rgb_frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)

results = self.hands.process(rgb_frame)

if results.multi_hand_landmarkslandmarks:

for hand_landmarks in results.multi_hand_landmarkslandmarks:

# 绘制手部关键点

self.mp_drawing.draw_landmarks(

marks(

frame, hand_landmarks, self.mp_hands.HAND_CONNECTIONS)

# 应用旋转特效

frame = self.apply_rotation_effect(frame, hand_landmarks.landmark, rotation_angle)

return frame

def main:

effect = PalmRotationEffect

# 打开摄像头

cap = cv2.VideoCapture(0)

if not cap.isOpened:

print("无法打开摄像头")

return

print("按 'q' 退出程序")

print("按 'r' 重置旋转角度")

print("移动手掌查看旋转效果")

rotation_angle = 0

while True:

ret, frame = cap.read

if not ret:

break

# 更新旋转角度（模拟动画）

rotation_angle += 30

if rotation_angle >= 360:

rotation_angle = 0

# 处理帧

processed_frame = effect.process_frame(frame, rotation_angle)

# 显示提示文本

cv2.putText.putText(processed_frame, f"Rotation: {rotation_angle} degrees",

(10, 30), cv2.FONT_HERSHEY_SIMPLEX, 0.7, (0, 255, 0), 2)

cv2.imshow('Palm Rotation Effect', processed_frame)

key = cv2.waitKey(1) & 0xFF

if key == ord('q'):

break

elif key == ord('r'):

rotation_angle = 0

cap.release

cv2.destroy.destroyAllWindows

if __name__ == "__main__":

main

使用说明

1. 环境要求：

2. 安装依赖：

bash

pip install opencv-python mediapipe numpy scipy

3. 操作方法：

特效特点

扩展建议

1. 增强视觉效果：可以添加发光、粒子效果等

2. 自定义旋转模式：支持用户定义旋转速度和方向

3. 多手势支持：扩展到多个手势的不同旋转效果

4. AR集成：可以将此效果集成到AR应用中

这个实现提供了基础的旋转特效，您可以根据需要进行进一步的定制和优化。