树莓派4B目标/动物识别报错：resize函数断言失败(-215)

错误原因 #

这个错误的核心是传入net.detect()的图像为空——你的代码中cap.read()没有成功读取到摄像头帧，导致img是无效的空对象，后续OpenCV的resize操作因缺少图像尺寸信息触发断言失败。

解决方案 #

1. 增加摄像头帧读取校验 #

修改主循环逻辑，先判断帧读取是否成功，避免传入空图像到检测函数：

if __name__ == "__main__":
    cap = cv2.VideoCapture(0)
    cap.set(3,640)
    cap.set(4,480)

    while True:
        success, img = cap.read()
        # 检查是否成功读取帧
        if not success:
            print("摄像头帧读取失败，退出循环")
            break
        result, objectInfo = getObjects(img,0.45,0.2)
        cv2.imshow("Output", result)
        # 按q键退出循环，同时释放资源
        if cv2.waitKey(1) & 0xFF == ord('q'):
            break
    # 释放摄像头资源和窗口
    cap.release()
    cv2.destroyAllWindows()

2. 确认摄像头设备索引 #

树莓派的摄像头设备索引可能不是0，执行以下命令查看可用视频设备：

ls /dev/video*

如果输出包含/dev/video1，尝试修改VideoCapture的参数：

cap = cv2.VideoCapture(1)
# 或者指定V4L2驱动确保兼容性
cap = cv2.VideoCapture(0, cv2.CAP_V4L2)

3. 验证摄像头硬件与系统设置 #

• 确认摄像头已正确连接到树莓派CSI接口
• 运行sudo raspi-config，进入Interface Options -> Camera启用摄像头，重启树莓派生效

4. 修复摄像头访问权限 #

将当前用户添加到video组以获取设备访问权限：

sudo usermod -aG video administrador

注销并重新登录后生效。

原问题代码与报错信息 #

import cv2

#thres = 0.45 # Threshold to detect object

classNames = []
classFile = "/home/administrador/Desktop/Object_Detection_Files/coco.names"
with open(classFile,"rt") as f:
    classNames = f.read().rstrip("\n").split("\n")

configPath = "/home/administrador/Desktop/Object_Detection_Files/ssd_mobilenet_v3_large_coco_2020_01_14.pbtxt"
weightsPath = "/home/administrador/Desktop/Object_Detection_Files/frozen_inference_graph.pb"

net = cv2.dnn_DetectionModel(weightsPath,configPath)
net.setInputSize(320,320)
net.setInputScale(1.0/ 127.5)
net.setInputMean((127.5, 127.5, 127.5))
net.setInputSwapRB(True)


def getObjects(img, thres, nms, draw=True, objects=[]):
    classIds, confs, bbox = net.detect(img,confThreshold=thres,nmsThreshold=nms)
    #print(classIds,bbox)
    if len(objects) == 0: objects = classNames
    objectInfo =[]
    if len(classIds) != 0:
        for classId, confidence,box in zip(classIds.flatten(),confs.flatten(),bbox):
            className = classNames[classId - 1]
            if className in objects:
                objectInfo.append([box,className])
                if (draw):
                    cv2.rectangle(img,box,color=(0,255,0),thickness=2)
                    cv2.putText(img,classNames[classId-1].upper(),(box[0]+10,box[1]+30),
                    cv2.FONT_HERSHEY_COMPLEX,1,(0,255,0),2)
                    cv2.putText(img,str(round(confidence*100,2)),(box[0]+200,box[1]+30),
                    cv2.FONT_HERSHEY_COMPLEX,1,(0,255,0),2)

    return img,objectInfo


if __name__ == "__main__":

    cap = cv2.VideoCapture(0)
    cap.set(3,640)
    cap.set(4,480)
    #cap.set(10,70)


    while True:
        success, img = cap.read()
        result, objectInfo = getObjects(img,0.45,0.2)
        #print(objectInfo)
        cv2.imshow("Output",img)
        cv2.waitKey(1)

报错回溯：

Traceback (most recent call last):
  File "/home/administrador/Desktop/Object_Detection_Files/object-ident.py", line 50, in <module>
result, objectInfo = getObjects(img,0.45,0.2)
  File "/home/administrador/Desktop/Object_Detection_Files/object-ident.py", line 21, in getObjects
    classIds, confs, bbox = net.detect(img,confThreshold=thres,nmsThreshold=nms)
cv2.error: OpenCV(4.4.0) /home/administrador/opencv-4.4.0/modules/imgproc/src/resize.cpp:3929: error: (-215:Assertion failed) !ssize.empty() in function 'resize'

内容的提问来源于stack exchange，提问作者Samuel LAZALDE HERNANDEZ