include "FAST/Importers/ImageFileImporter.hpp"

include "FAST/Visualization/ImageRenderer/ImageRenderer.hpp"

include "FAST/Visualization/SegmentationRenderer/SegmentationRenderer.hpp"

include "FAST/Visualization/SimpleWindow.hpp"

include "FAST/Algorithms/GradientVectorFlow/EulerGradientVectorFlow.hpp"

include "FAST/Algorithms/GradientVectorFlow/MultigridGradientVectorFlow.hpp"

using namespace fast;

int main() { auto importer = ImageFileImporter::create("d:\1.jpg"); auto gvf = MultigridGradientVectorFlow::create()->connect(importer); auto imageRenderer = ImageRenderer::create()->connect(importer); auto segmentationRenderer = SegmentationRenderer::create()->connect(gvf); auto window = SimpleWindow2D::create()->connect({ imageRenderer, segmentationRenderer });

ifdef FAST_CONTINUOUS_INTEGRATION

// This will automatically close the window after 5 seconds, used for CI testing
window->setTimeout(5 * 1000);

endif

window->run();
return 0;

}

The source code can be compiled, but it will run into errors!

To Reproduce The source code can be compiled, but it will run into errors.Run will throw an exception.

virtual bool notify(QObject receiver, QEvent event) { try { return QApplication::notify(receiver, event); } catch(Exception &e) { Reporter::error() << "FAST exception caught in Qt event handler " << e.what() << Reporter::end(); throw e;

System:

OS and version: [e.g. Windows 10]
GPU and OpenCL vendor (NVIDIA, Intel)

Expected behavior Can you give an example to correctly use EulerGradientVectorFlow and MultigridGradientVectorFlow?

Screenshots If applicable, add screenshots to help explain your problem.

smistad commented 2 years ago

A couple of comments to your code:

Input to gradient vector field (GVF) has to be a vector field, not an image. Thus use ImageGradient on your image first
MultigridGradientVectorFlow only supports 3D, for 2D use EulerGradientVectorFlow
GVF is not a segmentation algorithm, but it can be used for segmentation. Output of GVF is a vector field, so you have to use the VectorFieldColorRenderer to display it.

Here is a working python example showing how GVF can be applied and visualized on a 2D grayscale image:

import fast

importer = fast.ImageFileImporter.create(fast.Config.getTestDataPath() + "retina.png")
gradient = fast.ImageGradient.create().connect(importer)
gvf = fast.EulerGradientVectorFlow.create().connect(gradient)

renderer = fast.ImageRenderer.create().connect(importer)
renderer2 = fast.VectorFieldColorRenderer.create().connect(gvf)
fast.SimpleWindow2D.create().connect([renderer, renderer2]).run()

Screenshot from 2021-09-13 10-57-33

For questions, please use the gitter chat instead: https://gitter.im/smistad/FAST

libaineu2004 commented 2 years ago

OK. I hope to add GVF usage examples to https://github.com/smistad/FAST/tree/master/source/FAST/Examples