Third-Party Prerequisites

Required

This example generates CUDA MEX and has the following third-party requirements.

Optional

For non-MEX builds such as static, dynamic libraries or executables, this example has the following additional requirements.

Verify GPU Environment

Use thecoder.checkGpuInstall(GPU Coder)function to verify that the compilers and libraries necessary for running this example are set up correctly.

envCfg = coder.gpuEnvConfig('host'); envCfg.DeepLibTarget ='cudnn'; envCfg.DeepCodegen = 1; envCfg.Quiet = 1; coder.checkGpuInstall(envCfg);

Get Pretrained DAGNetwork

This example uses theyolov2ResNet50VehicleExampleMAT-file containing the pretrained network. The file is approximately 98MB in size. Download the file from the MathWorks website.

matFile = matlab.internal.examples.downloadSupportFile('vision/data','yolov2ResNet50VehicleExample.mat'); vehicleDetector = load(matFile); net = vehicleDetector.detector.Network

net = DAGNetwork with properties: Layers: [150×1 nnet.cnn.layer.Layer] Connections: [162×2 table] InputNames: {'input_1'} OutputNames: {'yolov2OutputLayer'}

The DAG network contains 150 layers including convolution, ReLU, and batch normalization layers and the YOLO v2 transform and YOLO v2 output layers. To display an interactive visualization of the deep learning network architecture, use theanalyzeNetworkfunction.

analyzeNetwork(net);

Theyolov2_detectEntry-Point Function

Theyolov2_detect.mentry-point function takes an image input and runs the detector on the image using the deep learning network saved in theyolov2ResNet50VehicleExample.matfile. The function loads the network object from theyolov2ResNet50VehicleExample.matfile into a persistent variableyolov2Objand reuses the persistent object on subsequent detection calls.

type('yolov2_detect.m')

function outImg = yolov2_detect(in,matFile) % Copyright 2018-2021 The MathWorks, Inc. persistent yolov2Obj; if isempty(yolov2Obj) yolov2Obj = coder.loadDeepLearningNetwork(matFile); end % Call to detect method [bboxes,~,labels] = yolov2Obj.detect(in,'Threshold',0.5); % Convert categorical labels to cell array of charactor vectors labels = cellstr(labels); % Annotate detections in the image. outImg = insertObjectAnnotation(in,'rectangle',bboxes,labels);

Run MEX Code Generation

To generate CUDA code for the entry-point function, create a GPU code configuration object for a MEX target and set the target language to C++. Use thecoder.DeepLearningConfig(GPU Coder)function to create aCuDNNdeep learning configuration object and assign it to theDeepLearningConfigproperty of the GPU code configuration object. Run thecodegencommand specifying an input size of 224-by-224-by-3. This value corresponds to the input layer size of YOLOv2.

cfg = coder.gpuConfig('mex'); cfg.TargetLang ='C++'; cfg.DeepLearningConfig = coder.DeepLearningConfig('cudnn'); cfg.GenerateReport = true; inputArgs = {ones(224,224,3,“uint8”),coder.Constant(matFile)}; codegen-configcfgyolov2_detect-argsinputArgs

Code generation successful: View report

Run Generated MEX

Set up the video file reader and read the input video. Create a video player to display the video and the output detections.

videoFile ='highway_lanechange.mp4'; videoFreader = vision.VideoFileReader(videoFile,'VideoOutputDataType',“uint8”); depVideoPlayer = vision.DeployableVideoPlayer('Size','Custom','CustomSize',[640 480]);

Read the video input frame-by-frame and detect the vehicles in the video using the detector.

cont = ~isDone(videoFreader);whilecont I = step(videoFreader); in = imresize(I,[224,224]); out = yolov2_detect_mex(in,matFile); step(depVideoPlayer, out);% Exit the loop if the video player figure window is closedcont = ~isDone(videoFreader) && isOpen(depVideoPlayer);end

References

[1] Redmon, Joseph, and Ali Farhadi. "YOLO9000: Better, Faster, Stronger." 2017 IEEE Conference on Computer Vision and Pattern Recognition (CVPR). IEEE, 2017.

Copyright 2017-2021The MathWorks, Inc.