1. Get started

OpenCorr is developed and tested in Microsoft Visual Studio 2019 (VS, community version) on Windows 10. The environment is updated to VS 2022 and Windows 11 now. The codes, following the standard of ISO C++ 14, can be compiled using other C++ compiler like GCC, or on other OS like Linux/Unix. Developers working on Linux/Unix may refer to a sample of CMake script (https://github.com/vincentjzy/OpenCorr/examples/CMakeLists.txt). To work with this library, users are supposed to have basic knowledge and skill about integrated development environment like VS. The building environment requires four open source libraries:

• Eigen 3.4.0 (eigen.tuxfamily.org), used for basic operations of 2D matrix.
• OpenCV 4.6.0 (opencv.org), used to read images, extract and match the 2D image features.
• FFTW 3.3.5 (fftw.org), used to speed up the calculation of cross correlation.
• nanoflann (https://github.com/jlblancoc/nanoflann), used to search for the nearest neighbors to a point among a point cloud.

These libraries provide comprehensive instructions for installation. The main procedure can be summarized as the following steps:

(1) Download the source files (e.g., .h or .cpp), static library files (.lib), and dynamic link library files (.dll) from the websites;

(2) Place them into proper folders in your computer. For example, I created a project of name OpenCorr in VS. The source codes are stored in folder “D:\OpenCorr\OpenCorr”, the files of the four libraries mentioned above are placed in folder “D:\OpenCorr”, as shown in Figure 1.1;

(3) Set the paths of source files and static library files in VS through Project –> Properties, as illustrated in Figure 1.2;

(4) Set the additional dependencies in VS through Project –> Properties. Open the Additional Dependencies dialog, as shown in Figure 1.3;

Then, add the name list of static library files into the edit box. Beware that the file name ends with “d” in Debug mode for opencv lib.

(5) Place the dynamic link library files (.dll) into the folder where the executable programs are built (e.g. “D:\OpenCorr\x64\Release” in Figure 1.1), or the directories listed in system Path;

(6) Set OpenMP support to enable the acceleration on multi-core CPU, as shown in Figure 1.4.

To facilitate the configuration for beginners, we made a compressed package of Visual Studio solution and share it on Download page. Users may download and unzip it (e.g. using 7-Zip), then open OpenCorr.sln in VS 2019 or higher version of Visual Studio, and start programming.

There are a few examples in folder “examples” of GitHub repository along with images, which demonstrate how to make a DIC or DVC program by assembling the modules in OpenCorr. Before building the executables, make sure that the file paths in the codes are correctly set.