Viz2D

Viz2D is a visualization module for OpenCV. It features OpenCL/OpenGL, OpenCL/VAAPI interoperability and a GUI based on nanogui. It should be included in OpenCV-contrib once it is ready.

What is Viz2D?

Viz2D is a new way of writing graphical (on- and offscreen) applications with OpenCV. It is light-weight and unencumbered by problematic licenses.

Why Viz2D?

• OpenGL: Easy access to OpenGL
• GUI: Simple yet powerful user interfaces through NanoGUI
• Vector graphics: Elegant and fast vector graphics through NanoVG
• Video pipeline: Through a simple Source/Sink system videos can be displayed, edited and saved.
• Hardware acceleration: Automatic hardware acceleration usage where possible. (e.g. cl-gl sharing and VAAPI). Actually it is possible to write programs to run almost entirely on the GPU, given driver-features are available.

Attribution

• The author of the bunny video is (c) copyright Blender Foundation | www.bigbuckbunny.org.
• The author of the dance video is GNI Dance Company (Original video)
• The author of the video used in the beauty-demo video is Kristen Leanne (Original video)

Demos

The goal of the demos is to show how to use Viz2D in conjunction with interop options on Linux to create programs that run mostly (the part the matters) on the GPU. You only need to build my fork of OpenCV 4.x if you want to use cl-gl sharing on recent Intel platforms (Gen8 - Gen12).

There are currently eight demos. The shader-demo, font-demo, optflow-demo and beauty-demo can be compiled to WebAssembly using Emscripten but for now you have to figure out how to do it yourself :).

Online Demos

Please note that the following online demos are slower and/or have less features than the native versions.

• https://viel-zu.org/opencv/shader
• https://viel-zu.org/opencv/font
• https://viel-zu.org/opencv/optflow
• https://viel-zu.org/opencv/beauty

Requirements

• C++20 (at the moment)
• OpenGL 4/OpenGL ES 3.0

Optional requirements

• Support for OpenCL 1.2
• Support for cl_khr_gl_sharing and cl_intel_va_api_media_sharing OpenCL extensions.
• If you want cl-gl sharing on a recent Intel Platform (Gen8 - Gen12) you currently need to install compute-runtime from source and my OpenCV fork

Dependencies

• OpenCV 4.x
• EGL
• GLEW
• GLFW3
• nanovg
• nanogui

tetra-demo

Renders a rainbow tetrahedron on blue background using OpenGL, applies a glow effect using OpenCV (OpenCL) and encodes on the GPU (VAAPI).

https://user-images.githubusercontent.com/287266/222984424-e0914bd4-72f3-4777-8a61-28dee6dd3573.mp4

video-demo

Renders a rainbow tetrahedron on top of a input-video using OpenGL, applies a glow effect using OpenCV (OpenCL) and decodes/encodes on the GPU (VAAPI).

https://user-images.githubusercontent.com/287266/222984530-c8c39997-ed3c-4675-92c9-40e4a7ea306a.mp4

shader-demo

Renders a mandelbrot fractal zoom. Uses shaders, OpenCL and VAAPI together.

https://user-images.githubusercontent.com/287266/222971445-13b75aee-f190-419d-9772-404d32ff61f2.mp4

nanovg-demo

Renders a color wheel on top of an input-video using nanovg (OpenGL), does colorspace conversions using OpenCV (OpenCL) and decodes/encodes on the GPU (VAAPI).

https://user-images.githubusercontent.com/287266/222984631-a7e3522a-8713-4413-ab5e-e6b55cd52ce8.mp4

font-demo

Renders a Star Wars like text crawl using nanovg (OpenGL), uses OpenCV (OpenCL) for a pseudo 3D effect and encodes on the GPU (VAAPI).

https://user-images.githubusercontent.com/287266/222984217-50af8dc1-72cb-4998-babe-53a2114745cf.mp4

optflow-demo

My take on a optical flow visualization on top of a video. Uses background subtraction (OpenCV/OpenCL) to isolate areas with motion, detects features to track (OpenCV/OpenCL), calculates the optical flow (OpenCV/OpenCL), uses nanovg for rendering (OpenGL) and post-processes the video (OpenCL). Decodes/encodes on the GPU (VAAPI).

https://user-images.githubusercontent.com/287266/222980868-e032bc80-0a2a-4406-b64e-7b2acdc22416.mp4

pedestrian-demo

Pedestrian detection using HOG with a linear SVM, non-maximal suppression and tracking using KCF. Uses nanovg for rendering (OpenGL), detects using a linear SVM (OpenCV/OpenCL), filters resuls using NMS (CPU) and tracks using KCF (CPU). Decodes/encodes on the GPU (VAAPI).

https://user-images.githubusercontent.com/287266/222980241-d631f7e5-e7a3-446e-937e-bce34e194bd1.mp4

beauty-demo

Face beautification using face landmark detection (OpenCV/OpenCL), nanovg (OpenGL) for drawing masks and multi-band blending (CPU) to put it all together.

https://user-images.githubusercontent.com/287266/222982914-ff5be485-4aec-4d6b-9eef-378f6b10d773.mp4

Instructions for Ubuntu 22.04.2 LTS

You need to build nanovg, nanogui and OpenCV with Viz2D

Install required packages

apt install vainfo clinfo libqt5opengl5-dev freeglut3-dev ocl-icd-opencl-dev libavcodec-dev libavdevice-dev libavfilter-dev libavformat-dev libavutil-dev libpostproc-dev libswresample-dev libswscale-dev libglfw3-dev libstb-dev libglew-dev cmake make git-core build-essential opencl-clhpp-headers pkg-config zlib1g-dev doxygen

Build nanovg

git clone https://github.com/inniyah/nanovg.git
mkdir nanovg/build
cd nanovg/build
cmake -DCMAKE_BUILD_TYPE=Release ..
make -j8
sudo make install

Build nanogui

git clone --recursive https://github.com/mitsuba-renderer/nanogui.git
mkdir nanogui/build
cd nanogui/build
cmake -DCMAKE_BUILD_TYPE=Release -DNANOGUI_BACKEND=OpenGL -DNANOGUI_BUILD_EXAMPLES=OFF -DNANOGUI_BUILD_GLFW=OFF -DNANOGUI_BUILD_PYTHON=OFF ..
make -j8
sudo make install

Build OpenCV with Viz2D using C++20

git clone --branch 4.x https://github.com/opencv/opencv.git
git clone https://github.com/kallaballa/Viz2D.git
mkdir opencv/build
cd opencv/build
cmake -DCMAKE_CXX_STANDARD=20 -DCMAKE_BUILD_TYPE=Release -DBUILD_opencv_viz2d=ON -DBUILD_opencv_python_tests=OFF -DBUILD_opencv_js_bindings_generator=OFF -DBUILD_opencv_python_bindings_generator=OFF -DBUILD_opencv_python3=OFF -DOPENCV_ENABLE_GLX=ON -DOPENCV_FFMPEG_ENABLE_LIBAVDEVICE=ON -DWITH_OPENGL=ON -DWITH_QT=ON -DWITH_FFMPEG=ON -DOPENCV_FFMPEG_SKIP_BUILD_CHECK=ON -DWITH_VA=ON -DWITH_VA_INTEL=ON -DBUILD_PERF_TESTS=OFF -DBUILD_TESTS=OFF -DBUILD_EXAMPLES=OFF -DOPENCV_EXTRA_MODULES_PATH=../../Viz2D/modules/ ..
make -j8
sudo make install

Download the example file

wget -O bunny.webm https://upload.wikimedia.org/wikipedia/commons/transcoded/f/f3/Big_Buck_Bunny_first_23_seconds_1080p.ogv/Big_Buck_Bunny_first_23_seconds_1080p.ogv.1080p.vp9.webm

Run the demos

src/tetra/tetra-demo

src/video/video-demo bunny.webm

src/shader/shader-demo bunny.webm

src/nanovg/nanovg-demo bunny.webm

src/font/font-demo

src/optflow/optflow-demo bunny.webm

src/pedestrian/pedestrian-demo bunny.webm

src/beauty/beauty-demo bunny.webm