This tutorial walks through the steps of creating a C++ JeVois module that has some external dependencies – here the excellent Dlib C++11 library of machine vision algorithms.

Setting up

First go through the steps outlined in Setting up for programming JeVois
Since we just want to compile a new module, we do not need to re-compile jevois and jevoisbase, we just use the pre-compiled versions provided by the JeVois Ubuntu packages. Thus, we only need to:
- Install Ubuntu package jevois-sdk-dev using instructions from http://jevois.usc.edu
- Use the script jevois-create-module provided by jevois-sdk-dev to create a new module from scratch.
- Compile the module using rebuild-host.sh and rebuild-platform.sh scripts that are in the module's directory.

Creating the module

We use the script jevois-create-module which will grab sample module code from GitHub, and will also immediately change names of classes and files to match our new module's name: usage is jevois-create-module <VendorName> <ModuleName>, so here let us just run:

cd
jevois-create-module Tutorial FaceDetector

you should now have the following:

facedetector/
├── CMakeLists.txt
├── COPYING
├── INSTALL
├── README
├── rebuild-host.sh
├── rebuild-platform.sh
├── share
│   └── README.txt
└── src
    └── Modules
        └── FaceDetector
            ├── FaceDetector.C
            ├── icon.png
            ├── postinstall
            └── screenshot1.png

Pulling the dependency

Let's write a small shell script to get Dlib, so that others can use that script when they want to compile our module. We create facedetector/download-dlib.sh as follows:

#!/bin/bash
# Download and extract dlib:
 
ver=19.15
 
if [ -d dlib ]; then
    echo "dlib/ directory already present! Delete it if you want to reinstall -- SKIPPING DLIB DOWNLOAD"
    exit 0
fi
 
wget http://dlib.net/files/dlib-${ver}.tar.bz2
tar jxvf dlib-${ver}.tar.bz2
/bin/rm dlib-${ver}.tar.bz2
mv dlib-${ver} dlib

This script will download Dlib with a given version, unpack, and install into facedetector/dlib/.

Downloading a fixed version is usually better than downloading the latest version, as changes in the latest version may introduce incompatibilities with our module, which would confuse future users. When a new version of Dlib is available, we will download it, test it with our module, make any adjustments, and update this download script.

Run the script from inside directory facedetector by calling:

cd facedetector

./download-dlib.sh

To make sure Dlib is automatically pulled and installed, we add the following line to both rebuild-host.sh and rebuild-platform.sh, somewhere before the make command is invoked:

# Get dlib if not here:

if [ ! -d dlib ]; then ./download-dlib.sh; fi

Compiling the dependency

We now turn to the docs of our dependency to try to understand how it should be compiled.

We find two options at http://dlib.net/compile.html

with CMake, compiling Dlib as a sub-project
directly from the command-line without cmake

After trying the first option, we could not make it work. But the second option worked fine. We simply add dlib/all/source.cpp as a new C++ file that needs to be compiled into our module. We also add dlib to our include path, and finally, after reading http://dlib.net/compile.html until the end, we add flag DLIB_NO_GUI_SUPPORT since JeVois has no display. We end up with the following modified CMakeLists.txt for our module:

cmake_minimum_required(VERSION 3.1)
 
## Set vendor names, our modules will be placed in a directory by that name under /jevois/modules:
set(JEVOIS_VENDOR "Tutorial")
set(JEVOIS_CONFIG "/jevois/config" CACHE STRING "Path to JeVois config to use")
 
## Include helper functions, config, etc from the JeVois install:
set(CMAKE_MODULE_PATH ${JEVOIS_CONFIG})
include(jevois_config)
include(JeVois)
 
## Set project name, detects compiler (which has been set by our helper module). Then set some compilation flags:
project(facedetector)
jevois_project_set_flags()
include_directories(${CMAKE_CURRENT_SOURCE_DIR})
 
## Setup our modules that are in src/Modules:
jevois_setup_modules(src/Modules "")
 
## Disable GUI support in Dlib:
add_definitions("-DDLIB_NO_GUI_SUPPORT")
 
## Include dlib include files:
include_directories("dlib")
 
## Add dlib source files (see http://dlib.net/compile.html):
target_sources(FaceDetector PRIVATE dlib/dlib/all/source.cpp)
 
## Add any link libraries for our module:
target_link_libraries(FaceDetector ${JEVOIS_OPENCV_LIBS} opencv_imgproc opencv_core)
 
## Install any shared resources (cascade classifiers, neural network weights, etc) in the share/ sub-directory:
install(DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/share"
  DESTINATION "${JEVOIS_INSTALL_ROOT}" COMPONENT bin)
 
## Wrapping up:
jevois_project_finalize()  # call this last in your CMakeLists.txt, will un-mount the live microSD if applicable

Note

Have a look at the CMakeLists.txt of jevoisbase, available at https://github.com/jevois/jevoisbase/blob/master/CMakeLists.txt - it contains many examples of how to import different kinds of C++ and C dependencies into JeVois modules. Typically, we end up using the following CMake commands:

include_directories() to add directories that contain include files.
target_sources() to add source files that should be compiled. For complex dependencies with tons of source files, usually we use shell commands to list them, see for example the ARToolkit or TensorFlow sections in the CMakelists.txt of jevoisbase.
target_link_libraries() to add libraries that your module should be linked against.
add_definitions() if you need to set compiler flags for your dependency.

Writing the module

We are now ready to write the module.

We edit facedetector/src/Modules/FaceDetector.C to include the face detection algorithm described in http://dlib.net/face_detection_ex.cpp.html

One thing that we need to resolve is how to get our images from the JeVois sensor into the Dlib image format. A quick web search reveals that Dlib provides functions to reinterpret (without copy) OpenCV images as Dlib images. So we will use that, for example as suggested at https://stackoverflow.com/questions/29118317/how-to-convert-mat-to-array2drgb-pixel

So we will grab into JeVois YUYV RawImage, convert to OpenCV RGB, and reinterpret that as Dlib RGB.

As far as output, let us just do a very simple layout for this module where we show the input video with boxes drawn around detected faces, and a little 24-pixel tall message area below to display the number of detections. So, we plan for 320x240 video capture from the sensor and 320x264 video output to USB.

We end up with this module, which is very similar to many of the modules in jevoisbase:

// ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//
// JeVois Smart Embedded Machine Vision Toolkit - Copyright (C) 2016 by Laurent Itti, the University of Southern
// California (USC), and iLab at USC. See http://iLab.usc.edu and http://jevois.org for information about this project.
//
// This file is part of the JeVois Smart Embedded Machine Vision Toolkit.  This program is free software; you can
// redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software
// Foundation, version 2.  This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
// without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
// License for more details.  You should have received a copy of the GNU General Public License along with this program;
// if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
//
// Contact information: Laurent Itti - 3641 Watt Way, HNB-07A - Los Angeles, CA 90089-2520 - USA.
// Tel: +1 213 740 3527 - itti@pollux.usc.edu - http://iLab.usc.edu - http://jevois.org
// ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/*! \file */
 
#include <jevois/Core/Module.H>
#include <jevois/Image/RawImageOps.H>
#include <jevois/Debug/Timer.H>
 
#include <dlib/opencv/cv_image.h>
#include <dlib/array2d/array2d_generic_image.h>
#include <dlib/image_processing/frontal_face_detector.h>
 
// icon by dlib team
 
//! Face Detection using the Dlib C++ machine vision library
/*! Detect faces using the HOG (histogram of gradients) algorithm provided by dlib.
 
    This module is heavily inspired from
    http://dlib.net/face_detection_ex.cpp.html
 
    It is an example of how to use dlib with JeVois.
 
    For more information about dlib, see http://dlib.net - Dlib provides a large number of high-quality C++11 algorithms
    for machine vision, deep neural networks, image processing, and machine learning.
 
    @author Laurent Itti
 
    @videomapping YUYV 320 264 15.0 YUYV 320 240 15.0 JeVois FaceDetector
    @email itti\@usc.edu
    @address University of Southern California, HNB-07A, 3641 Watt Way, Los Angeles, CA 90089-2520, USA
    @copyright Copyright (C) 2018 by Laurent Itti, iLab and the University of Southern California
    @mainurl http://jevois.org
    @supporturl http://jevois.org/doc
    @otherurl http://iLab.usc.edu
    @license GPL v3
    @distribution Unrestricted
    @restrictions None
    \ingroup modules */
class FaceDetector : public jevois::StdModule
{
  private:
    dlib::frontal_face_detector itsDetector;
    
  public:
    //! Constructor
    FaceDetector(std::string const & instance) : jevois::StdModule(instance)
    {
      itsDetector = dlib::get_frontal_face_detector();
    }
    
    //! Virtual destructor for safe inheritance
    virtual ~FaceDetector() { }
 
    //! Processing function
    virtual void process(jevois::InputFrame && inframe, jevois::OutputFrame && outframe) override
    {
      static jevois::Timer timer("processing", 30, LOG_DEBUG);
 
      // Wait for next available camera image:
      jevois::RawImage const inimg = inframe.get();
 
      timer.start();
      
      // We only support YUYV pixels in this example, any resolution:
      unsigned int const w = inimg.width, h = inimg.height;
      inimg.require("input", inimg.width, inimg.height, V4L2_PIX_FMT_YUYV);
 
      // While we process it, start a thread to wait for out frame and paste the input into it:
      jevois::RawImage outimg;
      auto paste_fut = std::async(std::launch::async, [&]() {
          outimg = outframe.get();
          outimg.require("output", outimg.width, h + 24, V4L2_PIX_FMT_YUYV);
 
          // Paste the current input image:
          jevois::rawimage::paste(inimg, outimg, 0, 0);
          jevois::rawimage::writeText(outimg, "JeVois dlib Face Detector", 3, 3, jevois::yuyv::White);
 
          // Blank out the bottom of the frame:
          jevois::rawimage::drawFilledRect(outimg, 0, h, w, outimg.height - h, jevois::yuyv::Black);
        });
 
      // Convert to OpenCV RGB:
      cv::Mat cvimg = jevois::rawimage::convertToCvRGB(inimg);
 
      // Reinterpret as dlib image:
      dlib::array2d<dlib::rgb_pixel> dlibimg;
      dlib::assign_image(dlibimg, dlib::cv_image<dlib::rgb_pixel>(cvimg));
 
      // Detect faces:
      std::vector<dlib::rectangle> dets = itsDetector(dlibimg);
      
      // Wait for paste thread to complete and let camera know we are done processing the input image:
      paste_fut.get(); inframe.done();
 
      // Draw the rectangles and send serial messages:
      jevois::rawimage::writeText(outimg, "Detected " + std::to_string(dets.size()) + " faces",
                                  3, h+6, jevois::yuyv::White);
 
      for (auto const & r : dets)
      {
        jevois::rawimage::drawRect(outimg, r.left(), r.top(), r.width(), r.height(), 2, jevois::yuyv::LightGreen);
        sendSerialImg2D(w, h, r.left() - r.width() / 2, r.top() - r.height() / 2, r.width(), r.height(), "face");
      }
      
      // Show processing fps:
      std::string const & fpscpu = timer.stop();
      jevois::rawimage::writeText(outimg, fpscpu, 3, h - 13, jevois::yuyv::White);
      
      // Send the output image with our processing results to the host over USB:
      outframe.send();
    }
};
 
// Allow the module to be loaded as a shared object (.so) file:
JEVOIS_REGISTER_MODULE(FaceDetector);

Compiling for host

Let us make sure Dlib compiles and links correctly and that our algorithm works by first compiling and running on host.

From inside the facedetector directory, we simply type:

./rebuild-host.sh

and get an output like:

itti@iLab0:~/facedetector$ ./rebuild-host.sh 
-- JeVois version 1.9.0
-- JEVOIS_PLATFORM: OFF
-- JEVOIS_VENDOR: Tutorial
-- JeVois microSD card mount point: /media/itti/JEVOIS
-- JeVois serial-over-USB device: /dev/ttyACM0
-- Install prefix for executable programs: /usr
-- Host path to jevois modules root: /jevois
-- The C compiler identification is GNU 7.3.0
-- The CXX compiler identification is GNU 7.3.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- JeVois SDK root: /lab/itti/jevois/software/jevois-sdk
-- Host path to jevois lib and data install root: /jevois
-- Adding compilation directives for C++ module FaceDetector base src/Modules
-- Configuring done
-- Generating done
-- Build files have been written to: /lab/itti/facedetector/hbuild
Scanning dependencies of target modinfo_FaceDetector
[ 25%] Generating ../src/Modules/FaceDetector/modinfo.yaml, ../src/Modules/FaceDetector/modinfo.html
[ 25%] Built target modinfo_FaceDetector
Scanning dependencies of target FaceDetector
[ 50%] Building CXX object CMakeFiles/FaceDetector.dir/src/Modules/FaceDetector/FaceDetector.C.o
[ 75%] Building CXX object CMakeFiles/FaceDetector.dir/dlib/dlib/all/source.cpp.o
In file included from /lab/itti/facedetector/dlib/dlib/all/../base64/../algs.h:111:0,
                 from /lab/itti/facedetector/dlib/dlib/all/../base64/base64_kernel_1.h:6,
                 from /lab/itti/facedetector/dlib/dlib/all/../base64/base64_kernel_1.cpp:6,
                 from /lab/itti/facedetector/dlib/dlib/all/source.cpp:11:
/lab/itti/facedetector/dlib/dlib/all/../global_optimization/global_function_search.cpp: In member function ‘void dlib::global_function_search::set_monte_carlo_upper_bound_sample_num(size_t)’:
/lab/itti/facedetector/dlib/dlib/all/../global_optimization/global_function_search.cpp:899:24: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
         DLIB_CASSERT(0 <= num);
                      ~~^~~~
/lab/itti/facedetector/dlib/dlib/all/../base64/../assert.h:157:47: note: in definition of macro ‘DLIB_WORKAROUND_VISUAL_STUDIO_BUGS’
 #define DLIB_WORKAROUND_VISUAL_STUDIO_BUGS(x) x
                                               ^
/lab/itti/facedetector/dlib/dlib/all/../base64/../assert.h:160:48: note: in expansion of macro ‘DLIBM_CASSERT’
 #define DLIBM_CASSERT_1_ARGS(exp)              DLIBM_CASSERT(exp,"")
                                                ^~~~~~~~~~~~~
/lab/itti/facedetector/dlib/dlib/all/../base64/../assert.h:157:47: note: in expansion of macro ‘DLIBM_CASSERT_1_ARGS’
 #define DLIB_WORKAROUND_VISUAL_STUDIO_BUGS(x) x
                                               ^
/lab/itti/facedetector/dlib/dlib/all/../global_optimization/global_function_search.cpp:899:9: note: in expansion of macro ‘DLIB_CASSERT’
         DLIB_CASSERT(0 <= num);
         ^
In file included from /lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/../threads/../member_function_pointer.h:6:0,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/../threads/threads_kernel_shared.h:11,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/../threads/threads_kernel_2.h:173,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/../threads/posix.h:4,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/../threads/threads_kernel.h:13,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/../threads.h:11,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/sockets_kernel_2.h:36,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/posix.h:4,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets.h:14,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/bsp.h:12,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/bsp.cpp:6,
                 from /lab/itti/facedetector/dlib/dlib/all/source.cpp:33:
/lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/../threads/../member_function_pointer/member_function_pointer_kernel_1.h: At global scope:
/lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/../threads/../member_function_pointer/member_function_pointer_kernel_1.h:343:18: warning: ‘void dlib::member_function_pointer<PARAM1, PARAM2, void, void>::mp_impl_const<T>::call(PARAM1, PARAM2) const [with T = dlib::impl::helper_parallel_for<dlib::impl::helper_parallel_for_funct<dlib::cpu::resize_bilinear(dlib::tensor&, long int, long int, const dlib::tensor&, long int, long int)::<lambda(long int)> > >; PARAM1 = long int; PARAM2 = long int]’ declared ‘static’ but never defined [-Wunused-function]
             void call (PARAM1 p1, PARAM2 p2) const  { (static_cast<const T*>(this->o)->*callback)(p1,p2); }
                  ^~~~
In file included from /lab/itti/facedetector/dlib/dlib/all/../cuda/../matrix.h:11:0,
                 from /lab/itti/facedetector/dlib/dlib/all/../cuda/tensor.h:8,
                 from /lab/itti/facedetector/dlib/dlib/all/../cuda/cpu_dlib.h:9,
                 from /lab/itti/facedetector/dlib/dlib/all/../cuda/cpu_dlib.cpp:8,
                 from /lab/itti/facedetector/dlib/dlib/all/source.cpp:82:
/lab/itti/facedetector/dlib/dlib/all/../cuda/../matrix/matrix_la.h: In function ‘long int dlib::svd4(dlib::svd_u_mode, bool, const dlib::matrix_exp<EXP>&, dlib::matrix<typename EXP::type, uM, uN, MM1, L1>&, dlib::matrix<typename EXP::type, qN, qX, MM2, L1>&, dlib::matrix<typename EXP::type, vM, vN, MM3, L1>&) [with EXP = dlib::matrix_op<dlib::op_trans<dlib::matrix_op<dlib::op_trans<dlib::matrix<double, 1, 2> > > > >; long int qN = 1; long int qX = 1; long int uM = 1; long int uN = 1; long int vM = 2; long int vN = 1; MM1 = dlib::memory_manager_stateless_kernel_1<char>; MM2 = dlib::memory_manager_stateless_kernel_1<char>; MM3 = dlib::memory_manager_stateless_kernel_1<char>; L1 = dlib::row_major_layout]’:
/lab/itti/facedetector/dlib/dlib/all/../cuda/../matrix/matrix_la.h:225:32: warning: iteration 1 invokes undefined behavior [-Waggressive-loop-optimizations]
             y = abs(q(i)) + abs(e(i));
                             ~~~^~~~~~
/lab/itti/facedetector/dlib/dlib/all/../cuda/../matrix/matrix_la.h:163:20: note: within this loop
         for (i=0; i<n; i++)
                   ~^~
/lab/itti/facedetector/dlib/dlib/all/../cuda/../matrix/matrix_la.h: In member function ‘void dlib::kalman_filter<states, measurements>::update(const dlib::matrix<double, measurements, 1>&) [with long int states = 2; long int measurements = 1]’:
/lab/itti/facedetector/dlib/dlib/all/../cuda/../matrix/matrix_la.h:412:37: warning: ‘*((void*)& v +-8)’ may be used uninitialized in this function [-Wmaybe-uninitialized]
                         v(j,i) = -x * s + z * c;
                                  ~~~^~~
/lab/itti/facedetector/dlib/dlib/all/../cuda/../matrix/matrix_la.h:1421:72: note: ‘*((void*)& v +-8)’ was declared here
         matrix<typename EXP::type, EXP::NC, EXP::NC,MM1, layout_type > v;
                                                                        ^
[100%] Linking CXX shared library FaceDetector.so
[100%] Built target FaceDetector
[ 25%] Generating ../src/Modules/FaceDetector/modinfo.yaml, ../src/Modules/FaceDetector/modinfo.html
[ 25%] Built target modinfo_FaceDetector
[100%] Built target FaceDetector
Install the project...
-- Install configuration: ""
-- Installing: /jevois/modules/Tutorial/FaceDetector
-- Installing: /jevois/modules/Tutorial/FaceDetector/icon.png
-- Installing: /jevois/modules/Tutorial/FaceDetector/postinstall
-- Installing: /jevois/modules/Tutorial/FaceDetector/screenshot1.png
-- Installing: /jevois/modules/Tutorial/FaceDetector/modinfo.html
-- Installing: /jevois/modules/Tutorial/FaceDetector/FaceDetector.C
-- Installing: /jevois/modules/Tutorial/FaceDetector/FaceDetector.so
-- Up-to-date: /jevois/share
-- Installing: /jevois/share/README.txt

So we had a few warnings within Dlib, but everything compiled fine. We are ready to test on host.

Testing on host

Before we can test on host, we need to add a video mapping for our module, with the resolutions our module expects. For that, we type:

sudo jevois-add-videomapping YUYV 320 264 15.0 YUYV 320 240 15.0 Tutorial FaceDetector

which adds an entry at the end of /jevois/config/videomappings.cfg on your host computer.

We also edit src/Modules/FaceDetector/postinstall with that video mapping. The postinstall script will be used by the JeVois camera when we upload our module to it later.

Now plug in a regular webcam to your host computer (not a JeVois camera)
and start

jevois-daemon

We need to find out which video mapping number was assigned to our module, for that we type:

listmappings

and we get a long list that includes FaceDetector in it. On our particular install,

   ...
   38 - OUT: YUYV 320x286 @ 30fps CAM: YUYV 320x240 @ 30fps MOD: JeVois:DemoQRcode C++
   39 - OUT: YUYV 320x266 @ 30fps CAM: YUYV 320x240 @ 30fps MOD: JeVois:ArUcoBlob C++
   40 - OUT: YUYV 320x264 @ 15fps CAM: YUYV 320x240 @ 15fps MOD: Tutorial:FaceDetector C++
   ...

We now quit jevois-daemon by sending it command quit
And we start it again, this time requesting videomapping number 40 that we found above:
jevois-daemon --videomapping=40
Here it is!

Running on platform

Let's now cross-compile and run our module on the JeVois camera.

We are going to use the jvpkg method as it is the easiest for single modules. In this method, we cross-compile the module and pack it into a .jvpkg archive (which is just a zip file), then copy that package to JEVOIS:/packages/ on the microSD of the JeVois camera. JeVois will unpack and install the package next time it starts up.

Check that src/Modules/FaceDetector/postinstall contains the video mapping our module needs, it should look like this:

#!/bin/sh
# This script is executed once after the module is installed by JeVois if it was added to the jevois/packages/ directory
# of the microSD card as a .jvpkg file. The script is deleted from the microSD card after execution.
#
# The caller script will set the current directory to the location of this script before launching the script.

# Add our video mappings to the main mappings file:
jevois-add-videomapping YUYV 320 264 15.0 YUYV 320 240 15.0 Tutorial FaceDetector

# Example of a simple message:
echo "FaceDetector is now installed"

To compile into a jvpkg package, we just run rebuild-platform.sh with no extra option. Output should look roughly like this:

itti@iLab0:~/facedetector$ ./rebuild-platform.sh 
-- JeVois version 1.9.0
-- JEVOIS_PLATFORM: ON
-- JEVOIS_VENDOR: Tutorial
-- JeVois microSD card mount point: /media/itti/JEVOIS
-- JeVois serial-over-USB device: /dev/ttyACM0
-- JEVOIS_MODULES_TO_STAGING: OFF
-- JEVOIS_MODULES_TO_MICROSD: OFF
-- JEVOIS_MODULES_TO_LIVE: OFF
-- Install prefix for executable programs: /var/lib/jevois-build/usr
-- Host path to jevois modules root: /var/lib/jevois-microsd
-- The C compiler identification is GNU 7.2.0
-- The CXX compiler identification is GNU 7.2.0
-- Check for working C compiler: /lab/itti/jevois/software/jevois-sdk/out/sun8iw5p1/linux/common/buildroot/host/usr/bin/arm-buildroot-linux-gnueabihf-gcc
-- Check for working C compiler: /lab/itti/jevois/software/jevois-sdk/out/sun8iw5p1/linux/common/buildroot/host/usr/bin/arm-buildroot-linux-gnueabihf-gcc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /lab/itti/jevois/software/jevois-sdk/out/sun8iw5p1/linux/common/buildroot/host/usr/bin/arm-buildroot-linux-gnueabihf-g++
-- Check for working CXX compiler: /lab/itti/jevois/software/jevois-sdk/out/sun8iw5p1/linux/common/buildroot/host/usr/bin/arm-buildroot-linux-gnueabihf-g++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- JeVois SDK root: /lab/itti/jevois/software/jevois-sdk
-- Host path to jevois lib and data install root: /lab/itti/facedetector/jvpkg
-- Adding compilation directives for C++ module FaceDetector base src/Modules
-- Configuring done
-- Generating done
-- Build files have been written to: /lab/itti/facedetector/pbuild
Scanning dependencies of target modinfo_FaceDetector
[ 25%] Generating ../src/Modules/FaceDetector/modinfo.yaml, ../src/Modules/FaceDetector/modinfo.html
[ 25%] Built target modinfo_FaceDetector
Scanning dependencies of target FaceDetector
[ 50%] Building CXX object CMakeFiles/FaceDetector.dir/src/Modules/FaceDetector/FaceDetector.C.o
[ 75%] Building CXX object CMakeFiles/FaceDetector.dir/dlib/dlib/all/source.cpp.o
In file included from /lab/itti/facedetector/dlib/dlib/all/../base64/../algs.h:111:0,
                 from /lab/itti/facedetector/dlib/dlib/all/../base64/base64_kernel_1.h:6,
                 from /lab/itti/facedetector/dlib/dlib/all/../base64/base64_kernel_1.cpp:6,
                 from /lab/itti/facedetector/dlib/dlib/all/source.cpp:11:
/lab/itti/facedetector/dlib/dlib/all/../global_optimization/global_function_search.cpp: In member function ‘void dlib::global_function_search::set_monte_carlo_upper_bound_sample_num(size_t)’:
/lab/itti/facedetector/dlib/dlib/all/../global_optimization/global_function_search.cpp:899:24: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
         DLIB_CASSERT(0 <= num);
                      ~~^~~~
/lab/itti/facedetector/dlib/dlib/all/../base64/../assert.h:157:47: note: in definition of macro ‘DLIB_WORKAROUND_VISUAL_STUDIO_BUGS’
 #define DLIB_WORKAROUND_VISUAL_STUDIO_BUGS(x) x
                                               ^
/lab/itti/facedetector/dlib/dlib/all/../base64/../assert.h:160:48: note: in expansion of macro ‘DLIBM_CASSERT’
 #define DLIBM_CASSERT_1_ARGS(exp)              DLIBM_CASSERT(exp,"")
                                                ^~~~~~~~~~~~~
/lab/itti/facedetector/dlib/dlib/all/../base64/../assert.h:157:47: note: in expansion of macro ‘DLIBM_CASSERT_1_ARGS’
 #define DLIB_WORKAROUND_VISUAL_STUDIO_BUGS(x) x
                                               ^
/lab/itti/facedetector/dlib/dlib/all/../global_optimization/global_function_search.cpp:899:9: note: in expansion of macro ‘DLIB_CASSERT’
         DLIB_CASSERT(0 <= num);
         ^
In file included from /lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/../threads/../member_function_pointer.h:6:0,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/../threads/threads_kernel_shared.h:11,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/../threads/threads_kernel_2.h:173,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/../threads/posix.h:4,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/../threads/threads_kernel.h:13,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/../threads.h:11,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/sockets_kernel_2.h:36,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/posix.h:4,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets.h:14,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/bsp.h:12,
                 from /lab/itti/facedetector/dlib/dlib/all/../bsp/bsp.cpp:6,
                 from /lab/itti/facedetector/dlib/dlib/all/source.cpp:33:
/lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/../threads/../member_function_pointer/member_function_pointer_kernel_1.h: At global scope:
/lab/itti/facedetector/dlib/dlib/all/../bsp/../sockets/../threads/../member_function_pointer/member_function_pointer_kernel_1.h:343:18: warning: ‘void dlib::member_function_pointer<PARAM1, PARAM2, void, void>::mp_impl_const<T>::call(PARAM1, PARAM2) const [with T = dlib::impl::helper_parallel_for<dlib::impl::helper_parallel_for_funct<dlib::cpu::resize_bilinear(dlib::tensor&, long int, long int, const dlib::tensor&, long int, long int)::<lambda(long int)> > >; PARAM1 = long int; PARAM2 = long int]’ declared ‘static’ but never defined [-Wunused-function]
             void call (PARAM1 p1, PARAM2 p2) const  { (static_cast<const T*>(this->o)->*callback)(p1,p2); }
                  ^~~~
In file included from /lab/itti/facedetector/dlib/dlib/all/../cuda/../matrix.h:11:0,
                 from /lab/itti/facedetector/dlib/dlib/all/../cuda/tensor.h:8,
                 from /lab/itti/facedetector/dlib/dlib/all/../cuda/cpu_dlib.h:9,
                 from /lab/itti/facedetector/dlib/dlib/all/../cuda/cpu_dlib.cpp:8,
                 from /lab/itti/facedetector/dlib/dlib/all/source.cpp:82:
/lab/itti/facedetector/dlib/dlib/all/../cuda/../matrix/matrix_la.h: In function ‘long int dlib::svd4(dlib::svd_u_mode, bool, const dlib::matrix_exp<EXP>&, dlib::matrix<typename EXP::type, uM, uN, MM1, L1>&, dlib::matrix<typename EXP::type, qN, qX, MM2, L1>&, dlib::matrix<typename EXP::type, vM, vN, MM3, L1>&) [with EXP = dlib::matrix_op<dlib::op_trans<dlib::matrix_op<dlib::op_trans<dlib::matrix<double, 1, 2> > > > >; long int qN = 1; long int qX = 1; long int uM = 1; long int uN = 1; long int vM = 2; long int vN = 1; MM1 = dlib::memory_manager_stateless_kernel_1<char>; MM2 = dlib::memory_manager_stateless_kernel_1<char>; MM3 = dlib::memory_manager_stateless_kernel_1<char>; L1 = dlib::row_major_layout]’:
/lab/itti/facedetector/dlib/dlib/all/../cuda/../matrix/matrix_la.h:225:32: warning: iteration 1 invokes undefined behavior [-Waggressive-loop-optimizations]
             y = abs(q(i)) + abs(e(i));
                             ~~~^~~~~~
/lab/itti/facedetector/dlib/dlib/all/../cuda/../matrix/matrix_la.h:163:20: note: within this loop
         for (i=0; i<n; i++)
                   ~^~
/lab/itti/facedetector/dlib/dlib/all/../cuda/../matrix/matrix_la.h: In member function ‘void dlib::kalman_filter<states, measurements>::update(const dlib::matrix<double, measurements, 1>&) [with long int states = 2; long int measurements = 1]’:
/lab/itti/facedetector/dlib/dlib/all/../cuda/../matrix/matrix_la.h:1421:72: warning: ‘*((void*)& v +-8)’ may be used uninitialized in this function [-Wmaybe-uninitialized]
         matrix<typename EXP::type, EXP::NC, EXP::NC,MM1, layout_type > v;
                                                                        ^
[100%] Linking CXX shared library FaceDetector.so
[100%] Built target FaceDetector
[ 25%] Generating ../src/Modules/FaceDetector/modinfo.yaml, ../src/Modules/FaceDetector/modinfo.html
[ 25%] Built target modinfo_FaceDetector
[100%] Built target FaceDetector
Install the project...
-- Install configuration: ""
-- Installing: /lab/itti/facedetector/jvpkg/modules/Tutorial/FaceDetector
-- Installing: /lab/itti/facedetector/jvpkg/modules/Tutorial/FaceDetector/icon.png
-- Installing: /lab/itti/facedetector/jvpkg/modules/Tutorial/FaceDetector/postinstall
-- Installing: /lab/itti/facedetector/jvpkg/modules/Tutorial/FaceDetector/screenshot1.png
-- Installing: /lab/itti/facedetector/jvpkg/modules/Tutorial/FaceDetector/modinfo.html
-- Installing: /lab/itti/facedetector/jvpkg/modules/Tutorial/FaceDetector/FaceDetector.C
-- Installing: /lab/itti/facedetector/jvpkg/modules/Tutorial/FaceDetector/FaceDetector.so
-- Set runtime path of "/lab/itti/facedetector/jvpkg/modules/Tutorial/FaceDetector/FaceDetector.so" to ""
-- Installing: /lab/itti/facedetector/jvpkg/share
-- Installing: /lab/itti/facedetector/jvpkg/share/README.txt

Note: Make sure JeVois software versions on your development machine and on your microSD card exactly match, otherwise your new module will fail to load. Here, for example, we see from our run of rebuild-platform.sh that we are using jevois-sdk-dev version 1.9.0. To check the version running on your microSD card, start JeVois Inventor and look at the bottom status bar when the camera is detected.

The module has been cross-compiled for the JeVois processor and the resulting files have been copied to ~/facedetector/jvpkg/, where they are ready to be packaged into a single JeVois package file that can later be copied to microSD and run on the smart camera.

To create the package, we run:
cd pbuild

make jvpkg

cd ..

and we obtain a file ~/facedetector/Tutorial_facedetector.jvpkg
Let's copy the file to our microSD. Either insert the microSD card into your desktop, or export it live from your connected JeVois camera as explained in Live access to contents of the microSD inside JeVois

Then copy Tutorial_facedetector.jvpkg into JEVOIS:/packages/ on the microSD.
Cleanly eject the card and restart JeVois. Upon restart, the camera will unpack and install our module. It will also add our video mapping for it from the contents of our postinstall file.
Let's fire up JeVois Inventor and find our new module:

Bingo, our Dlib-powered face detector is running on our JeVois camera!

Going further

Change the icon in src/Modules/FaceDetector/icon.png to a better one. Recommended size is 128x128. If you want to round the corners of your icon, you can use our script at https://github.com/jevois/jevois/blob/master/scripts/round-image-corners.sh
Dlib contains a lot of high-quality algorithms. Have a look at their examples and port some to JeVois.
Yet, this algorithm is not the fastest nor most robust face detector available on JeVois (indeed, it seems to be using only one CPU core). Have a look at DetectionDNN and PyDetectionDNN for the OpenCV face detection algorithm. Dlib does provide quite powerful detection of facial landmarks and face matching, though.
This module has been integrated into the standard JeVois distribution; it is available in github repo jevoisextra available at https://github.com/jevois/jevoisextra and is available on the standard microSD cards after JeVois version 1.9.1