How to get the coordinate of feature points of popsift::FeaturesDev? about popsift HOT 4 CLOSED

The FeaturesDev memory exists only in GPU memory, not in the CPU memory. To use the coordinates in the CPU after matching, you must transfer them first.

You could do something like this:

    FeaturesHost* features = new FeaturesHost( lFeatures->getFeatureCount(), lFeatures->getDescriptorCount() );
    features->pin( );
    cudaMemcpy( features->getFeatures(),
                             lFeatures->getFeatures();
                             lFeatures->getFeatureCount() * sizeof(Feature),
                             cudaMemcpyDeviceToHost );
    cudaMemcpy( features->getDescriptors(),
                             lFeatures->getDescriptors(),
                             lFeatures->getDescriptorCount() * sizeof(Descriptor),
                             cudaMemcpyDeviceToHost );
    features->unpin( );

from popsift.

The FeaturesDev memory exists only in GPU memory, not in the CPU memory. To use the coordinates in the CPU after matching, you must transfer them first.

You could do something like this:

    FeaturesHost* features = new FeaturesHost( lFeatures->getFeatureCount(), lFeatures->getDescriptorCount() );
    features->pin( );
    cudaMemcpy( features->getFeatures(),
                             lFeatures->getFeatures();
                             lFeatures->getFeatureCount() * sizeof(Feature),
                             cudaMemcpyDeviceToHost );
    cudaMemcpy( features->getDescriptors(),
                             lFeatures->getDescriptors(),
                             lFeatures->getDescriptorCount() * sizeof(Descriptor),
                             cudaMemcpyDeviceToHost );
    features->unpin( );

I tried and it worked! Thank you so much!

from popsift.

it works,thanks

from popsift.

I try to get all the descriptors and feature points on the CPU with following codes
std::unique_ptr<popsift::Features> sf;
sf.reset(sfeatures);
popsift::Feature* sfeature_list = sf->getFeatures();
std::vector<float> spoints(4 * numFeatures);
std::vector<float> sdesc(128 * numFeatures);
int width = 1920;
int height = 1080;

for(size_t i = 0; i < numFeatures; i++) { popsift::Feature pFeat = sfeature_list[i];
but the program crashes when i try to print the descriptors.

    cout << "pFeat.desc->features:" << ((pFeat.desc[0])->features[0[)<< endl;
    for(int oriIdx = 0; oriIdx < pFeat.num_ori; oriIdx++)
    {
        const popsift::Descriptor* pDesc = pFeat.desc[oriIdx];
        cout << "note here :" << ((pDesc->features)[0]) << endl;
        for(int k = 0; k < 128; k++)
        {
            sdesc[128 * i + k] = pDesc->features[k]; //==(*pDesc).features[k]
        }

        spoints[4 * i + 0] = std::min<float>(std::round(pFeat.xpos), width - 1);
        spoints[4 * i + 1] = std::min<float>(std::round(pFeat.ypos), height - 1);
        spoints[4 * i + 2] = pFeat.sigma;
        spoints[4 * i + 3] = pFeat.orientation[oriIdx];
    }
}

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