pytorch_cpp

This demo will show you how to use libtorch to build your C++ application.

Requirements
Build
Usage

Requirements

Pytorch (tag: pytorch v1.0)
Libtorch
OpenCV

Build

Step 1

Export your pytorch model to torch script file, We will simply use resnet50 in this demo

Step 2

Write your C++ program, check the file prediction.cpp for more detial.

PS: module->to(at::kCUDA) and input_tensor.to(at::kCUDA) will switch your model & tensor to GPU mode,
comment out them if you just want to use CPU mode.

Step 3

Write a CMakeLists.txt, the version of OpenCV must the same as your libtorch. Otherwise, you may get the compile error:

error: undefined reference to `cv::imread(std::string const&, int)'

check issues 14684 and issues 14620 for more details.

Usage

run model_trace.py, then you will get a file resnet50.pt
compile your cpp program, you need to use -DCMAKE_PREFIX_PATH=/absolute/path/to/libtorch, for example:

mkdir build
cd build
cmake -DCMAKE_PREFIX_PATH=/home/cgilab/pytorch/torch/lib/tmp_install ..
make

test your program

classifier <path-to-exported-script-module> <path-to-lable-file>

> ./classifier ../resnet50.pt ../label.txt
== Switch to GPU mode
== ResNet50 loaded!
== Label loaded! Let's try it
== Input image path: [enter Q to exit]
../pic/dog.jpg
== image size: [976 x 549] ==
== simply resize: [224 x 224] ==
    ============= Top-1 =============
    Label:  beagle
    With Probability:  99.1228%
    ============= Top-2 =============
    Label:  Walker hound, Walker foxhound
    With Probability:  0.469356%
    ============= Top-3 =============
    Label:  English foxhound
    With Probability:  0.110916%
== Input image path: [enter Q to exit]

../pic/shark.jpg
== image size: [800 x 500] ==
== simply resize: [224 x 224] ==
    ============= Top-1 =============
    Label:  tiger shark, Galeocerdo cuvieri
    With Probability:  92.2599%
    ============= Top-2 =============
    Label:  great white shark, white shark, man-eater, man-eating shark
    With Probability:  5.94252%
    ============= Top-3 =============
    Label:  hammerhead, hammerhead shark
    With Probability:  1.77418%
== Input image path: [enter Q to exit]
Q

Take it easy!!

ljch2018/PyTorch-CPP