[Q&A] raspberry pi 4 + NCS2 ngraph module not found

[semteuls]

Hello.

I installed the following version on my raspberry pi.

l_openvino_toolkit_runtime_raspbian_p_2021.3.394.tgz

When I run the demo program using Python, I get an error.

pi@raspberrypi:~/sw/openvino/deployment_tools/inference_engine/samples/python/object_detection_sample_ssd $ python3 object_detection_sample_ssd.py
Traceback (most recent call last):
File "object_detection_sample_ssd.py", line 26, in <module>
import ngraph as ng
ModuleNotFoundError: No module named 'ngraph'

Python 3.7.3 (default, Jan 22 2021, 20:04:44)
[GCC 8.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
>>> cv2.__version__
'4.5.2-openvino'

 Do I have to install the ngraph module separately?

Even after installing the source, I keep getting a compilation error.

Is there a solution?

Thanks.

[Peh_Intel · Accepted solution]

Hi semteuls,

Thanks for reaching out to us.

For your information, nGraph module is not included in the OpenVINO™ Toolkit for Raspbian OS Package. You have to build Open Source OpenVINO™ Toolkit for Raspbian OS in order to import the nGraph module.

Please refer to the steps below for building Open Source OpenVINO™ Toolkit for Raspbian OS:

1.    Set up build environment and install build tools

sudo apt update && sudo apt upgrade -y

sudo apt install build-essential

2.      Install CMake from source

cd ~/

wget https://github.com/Kitware/CMake/releases/download/v3.14.4/cmake-3.14.4.tar.gz

tar xvzf cmake-3.14.4.tar.gz

cd ~/cmake-3.14.4

./bootstrap

make -j4 && sudo make install

3.      Install OpenCV from source

sudo apt install git libgtk2.0-dev pkg-config libavcodec-dev libavformat-dev libswscale-dev python3-scipy libatlas-base-dev

cd ~/

git clone --depth 1 --branch 4.5.2 https://github.com/opencv/opencv.git

cd opencv && mkdir build && cd build

cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr/local ..

make -j4 && sudo make install

4.      Download source code and install dependencies

cd ~/

git clone --depth 1 --branch 2021.3 https://github.com/openvinotoolkit/openvino.git

cd ~/openvino

git submodule update --init --recursive

sh ./install_build_dependencies.sh

cd ~/openvino/inference-engine/ie_bridges/python/

pip3 install -r requirements.txt

5. Start CMake build

export OpenCV_DIR=/usr/local/lib/cmake/opencv4

cd ~/openvino

mkdir build && cd build

cmake -DCMAKE_BUILD_TYPE=Release \

-DCMAKE_INSTALL_PREFIX=/home/pi/openvino_dist \

-DENABLE_MKL_DNN=OFF \

-DENABLE_CLDNN=OFF \

-DENABLE_GNA=OFF \

-DENABLE_SSE42=OFF \

-DTHREADING=SEQ \

-DENABLE_OPENCV=OFF \

-DNGRAPH_PYTHON_BUILD_ENABLE=ON \

-DNGRAPH_ONNX_IMPORT_ENABLE=ON \

-DENABLE_PYTHON=ON \

-DPYTHON_EXECUTABLE=$(which python3.7) \

-DPYTHON_LIBRARY=/usr/lib/arm-linux-gnueabihf/libpython3.7m.so \

-DPYTHON_INCLUDE_DIR=/usr/include/python3.7 \

-DCMAKE_CXX_FLAGS=-latomic ..

make -j4 && sudo make install

6.      Configure the Intel® Neural Compute Stick 2 Linux USB Driver

sudo usermod -a -G users "$(whoami)"

source /home/pi/openvino_dist/bin/setupvars.sh

sh /home/pi/openvino_dist/install_dependencies/install_NCS_udev_rules.sh

7.      Verify nGraph module binding to Python

source /home/pi/openvino_dist/bin/setupvars.sh

cd /home/pi/openvino_dist/deployment_tools/inference_engine/samples/python/object_detection_sample_ssd

python3 object_detection_sample_ssd.py -h

Regards,

Peh

[dengyu]

The problem is not solved

[JimmyMiller]

Thank you Peh, this script does correctly install openVino with ngraph.

For my Rasbian Buster(32 bit) kernel 5.10.103-v7l+ I had to install Cython first, and add its location to $PATH.

Also the line

git submodule update --init --recursive

will throw an error if you haven't entered an email or name into git config.

Otherwise, it worked so thanks! I can now use ngraph for my inferencing!

[Peh_Intel]

Hi dengyu,

Please open a new thread with the elaboration of your issue encountered for us to better assist you.

Regards,

Peh

[Peh_Intel]

Hi semteuls,

This thread will no longer be monitored since we have provided a solution. If you need any additional information from Intel, please submit a new question.

Regards,

Peh

[semteuls]

Thanks.

However, it has not been practiced yet.
Let's install it from source.