Unable to Compile a QT App Utilizing PCL Visualizer: Missing VTK/MPI Components
This article aims to help developers solve the common issue of encountering errors related to missing VTK/MPI components when attempting to build a QT application utilizing the PCL Visualizer library.
Problem:
Users often encounter the error "Could NOT find MPI (missing: MPI_C_FOUND C)" when using CMake to build a QT application with PCL Visualizer. The error suggests that CMake cannot locate the necessary MPI components, even though MPI seems partially installed.
Analysis:
The issue stems from a potential incompatibility between CMake, VTK, and MPI versions. While recent CMake versions have addressed earlier issues related to FindMPI, specific versions might still face challenges.
Solutions:
Here's a breakdown of solutions, based on information from Stack Overflow and insights gained from the user's problem:
-
Verify MPI Installation:
- Check for MPI Components: Ensure that your system has installed both
mpiccandmpicxxin/usr/bin. You might need to install additional packages, such aslibopenmpi-dev, if they are not already present. - Correct Cmake Config Options: Verify if the
MPI_C_COMPILERandMPI_CXX_COMPILERvariables are properly set in yourCMakeLists.txt. Correctly setting these variables is crucial for CMake to find the MPI components correctly.
- Check for MPI Components: Ensure that your system has installed both
-
Update CMake:
- Newer CMake Versions: Outdated CMake versions might lack proper support for finding MPI components. Try updating CMake to a newer version if possible. Versions later than 3.15 are recommended to ensure compatibility with VTK and MPI.
-
Rebuild VTK:
- Build from Source: In some cases, building VTK from source might be necessary to resolve the missing component issue. Refer to VTK documentation for instructions on building from source. This approach gives you more control over the build process and enables you to customize VTK to meet your project's needs.
Additional Tips:
- Consult VTK Documentation: Refer to the VTK documentation for specific instructions on integrating VTK with your project. It might provide additional insights and workarounds for resolving the MPI component issue.
- Double-check Dependencies: Ensure that all necessary dependencies for PCL and VTK are correctly installed on your system. Missing dependencies can lead to unexpected errors.
- Utilize CMake Debugging: Use CMake's debugging features to identify the root cause of the error. You can enable verbose output or set breakpoints to pinpoint the problematic section in the CMake build process.
Illustrative Example:
Let's consider a simplified example demonstrating the potential integration of PCL Visualizer with a QT application.
CMakeLists.txt:
cmake_minimum_required(VERSION 3.15)
project(PCLVisualizerQT)
# Find PCL
find_package(PCL REQUIRED)
# Find VTK
find_package(VTK REQUIRED)
# Find MPI
find_package(MPI COMPONENTS C CXX REQUIRED)
# Define your QT project (adjust according to your QT setup)
# ...
# Link libraries
target_link_libraries(PCLVisualizerQT ${PCL_LIBRARIES} ${VTK_LIBRARIES} ${MPI_C_LIBRARIES} ${MPI_CXX_LIBRARIES})
# Add your source files
add_executable(PCLVisualizerQT main.cpp)
main.cpp (simplified example):
#include <pcl/visualization/pcl_visualizer.h>
#include <pcl/point_types.h>
// ... other headers
int main(int argc, char *argv[]) {
// Create a PCLVisualizer instance
pcl::visualization::PCLVisualizer::Ptr viewer (new pcl::visualization::PCLVisualizer ("3D Viewer"));
// ... further visualization code
return 0;
}
This example demonstrates how to include PCL, VTK, and MPI in your CMake project, ensuring that the necessary libraries are linked correctly.
Conclusion:
By carefully following the steps outlined in this article, developers can overcome the "missing VTK/MPI components" error and successfully build their QT application using PCL Visualizer. Remember to double-check dependencies, verify CMake configurations, and consider rebuilding VTK from source if necessary.
