[Question] In optFlow newPoints array descriptors are always empty

[vswdigitall]

Hi ACL,

ACL 19.02, built for CL, aarch64, FriendlyArm nanopi NEO4.

Why in optFlow new points descriptors always empty (only x,y, status computed ) such as error, orintation..?

pyramidInfo.init( 1, arm_compute::SCALE_PYRAMID_HALF, arm_compute::TensorShape( image.cols, image.rows ), arm_compute::Format::U8 );
            prevPyramid.init( pyramidInfo );
            pyramid.init( pyramidInfo );
            prevPts = arm_compute::CLKeyPointArray{ optFlowMaxPoints };
            pts = arm_compute::CLKeyPointArray{ optFlowMaxPoints };
            estimatedPts = arm_compute::CLKeyPointArray{ optFlowMaxPoints };
            prevPts.resize( optFlowMaxPoints );
            estimatedPts.resize( optFlowMaxPoints );

prevGausPyramid.configure( & clPrevRect, & prevPyramid, arm_compute::BorderMode::UNDEFINED, 0 );
            gausPyramid.configure( & clRect, & pyramid, arm_compute::BorderMode::UNDEFINED, 0 );
            optFlow.configure( & prevPyramid, & pyramid, & prevPts, & estimatedPts, & pts,
                               arm_compute::Termination::TERM_CRITERIA_BOTH, optFlowEps, optFlowIters, optFlowWinSize, false, arm_compute::BorderMode::UNDEFINED );

arm_compute::KeyPoint kpt{};
            kpt.x = pt.x;
            kpt.y = pt.y;
            kpt.tracking_status = 1;

How can i use estimated array?

Best regards, Viktor.

[morgolock]

Hi @vswdigitall

Could you please try using at least 3 levels for the pyramid? pyramidInfo.init( 3, arm_compute::SCALE_PYRAMID_HALF, arm_compute::TensorShape( image.cols, image.rows ), arm_compute::Format::U8 );

[vswdigitall]

Have tried 3 levels, but still zeros.

[morgolock]

Hi @vswdigitall

Would you please confirm that the problem you describe is that you get the output keypoints but the fields strength, scale, orientation, status and error are empty?

[vswdigitall]

Yes, it is. I have checked many times.

[morgolock]

Hi @vswdigitall

The struct Keypoint used in optical flow is also used by other functions, in particular by the corner detectors harris corners and fast corners. Not all the members are used in some functions, optical flow would only output the new point coordinates and the status.

ACL's vision functions are based on the OpenVX spec, please take a look at the documentation of the keypoint struct for more details: https://www.khronos.org/registry/OpenVX/specs/1.0/html/d4/dae/group__group__basic__features.html#d6/db0/structvx__keypoint__t

[vswdigitall]

Ok. Thanks. Closed.