C++ Demo - Object Detection (NanoDet) (#232)

* Functional and Refactored demo.cpp for MobileNet

* Fix inference timer text, added timer reset.

* Updated README.md, remove FPS text for single image processing

* Add matching saved image message

* Removing inference time printout for video inputs

* Update FPS text to 2 decimal places

* Update coding style for braces

* Address PR comments. Adjusted to C++11 standard.

* Addressed PR comments. Added C++11 cmake configuration, extracted classID and confidence function, and use NMSBoxesBatched now.

Author: ryan1288

models/object_detection_nanodet/CMakeLists.txt

@@ -0,0 +1,32 @@
+cmake_minimum_required(VERSION 3.24)
+set(project_name "opencv_zoo_object_detection_nanodet")
+
+PROJECT (${project_name})
+
+set(OPENCV_VERSION "4.9.0")
+set(OPENCV_INSTALLATION_PATH "" CACHE PATH "Where to look for OpenCV installation")
+find_package(OpenCV ${OPENCV_VERSION} REQUIRED HINTS ${OPENCV_INSTALLATION_PATH})
+# Find OpenCV, you may need to set OpenCV_DIR variable
+# to the absolute path to the directory containing OpenCVConfig.cmake file
+# via the command line or GUI
+
+file(GLOB SourceFile
+    "demo.cpp")
+# If the package has been found, several variables will
+# be set, you can find the full list with descriptions
+# in the OpenCVConfig.cmake file.
+# Print some message showing some of them
+message(STATUS "OpenCV library status:")
+message(STATUS "    config: ${OpenCV_DIR}")
+message(STATUS "    version: ${OpenCV_VERSION}")
+message(STATUS "    libraries: ${OpenCV_LIBS}")
+message(STATUS "    include path: ${OpenCV_INCLUDE_DIRS}")
+
+# Declare the executable target built from your sources
+add_executable(${project_name} ${SourceFile})
+
+# Set C++ compilation standard to C++11
+set(CMAKE_CXX_STANDARD 11)
+
+# Link your application with OpenCV libraries
+target_link_libraries(${project_name} PRIVATE ${OpenCV_LIBS})

models/object_detection_nanodet/README.md

@@ -7,6 +7,8 @@ Note:
 
 ## Demo
 
+### Python
+
 Run the following command to try the demo: 
 ```shell
 # detect on camera input
@@ -17,6 +19,23 @@ python demo.py --input /path/to/image -v
 Note: 
 - image result saved as "result.jpg"
 
+### C++
+
+Install latest OpenCV and CMake >= 3.24.0 to get started with:
+
+```shell
+# A typical and default installation path of OpenCV is /usr/local
+cmake -B build -D OPENCV_INSTALLATION_PATH=/path/to/opencv/installation .
+cmake --build build
+
+# detect on camera input
+./build/opencv_zoo_object_detection_nanodet
+# detect on an image
+./build/opencv_zoo_object_detection_nanodet -i=/path/to/image
+# get help messages
+./build/opencv_zoo_object_detection_nanodet -h
+```
+
 
 ## Results