According to The APEX-CV Library document, apexcv::LKPyramidOpticalFlow::Initialize has following arguments: aSrc0Desc, aSrc1Desc, aCoor0Desc, aCoor1Desc, aCoor1Desc_O.
I want to know meaning of aCoor0Desc, aCoor1Desc, and aCoor1Desc_O.
The arguments of apexcv::LKPyramidOpticalFlow is not corresponding to OpenCV function (cv::calcOpticalFlowPyrLK).
I think aCoor0Desc and aCoor1Desc are input point list which is tracking feature of aSrc0Desc and aSrc1Desc, and aCoor1Desc_O is output point list which is detected flow.
However, on my code, X/Y coordinate of aCoor1Desc_O becomes always (0,0) even if "reverve" field in output "Feature32S" is 1.
my code:
// Prepare buffer
const int CORNERS_MAX = 400;
uint8_t features_cur_[sizeof(icp::Feature32S) * CORNERS_MAX] = {0};
uint8_t features_prev_[sizeof(icp::Feature32S) * CORNERS_MAX] = {0};
uint8_t features_out_[sizeof(icp::Feature32S) * CORNERS_MAX] = {0};
icp::Feature32SDescriptor features_cur((void *)features_cur_, (void *)features_cur_, CORNERS_MAX);
icp::Feature32SDescriptor features_prev((void *)features_prev_, (void *)features_prev_, CORNERS_MAX);
icp::Feature32SDescriptor features_out((void *)features_out_, (void *)features_out_, CORNERS_MAX);
{
std::vector<cv::Point2f> features_cur_v;
std::vector<cv::Point2f> features_prev_v;
cv::goodFeaturesToTrack((cv::UMat)frame_prev, features_prev_v, CORNERS_MAX, 0.01, 3.0, cv::Mat(), 7, true, 0.08); // use OpenCV GFTT
cv::goodFeaturesToTrack((cv::UMat)frame_cur, features_cur_v, CORNERS_MAX, 0.01, 3.0, cv::Mat(), 7, true, 0.08);
for(cv::Point2f feature_cur : features_cur_v)
{
features_cur.Add(((int)feature_cur.x) << 8, ((int)feature_cur.y) << 8);
features_out.Add(((int)feature_cur.x) << 8, ((int)feature_cur.y) << 8); // apexcv::LKPyramidOpticalFlow requires features_out.getCount() >= features_cur.getCount()
}
for(cv::Point2f feature_prev : features_prev_v)
{
features_prev.Add(((int)feature_prev.x) << 8, ((int)feature_prev.y) << 8);
}
}
// Execute ApexCV
apexcv::LKPyramidOpticalFlow apex_processor;
apex_processor.Initialize(
/*aSrc0Desc*/ frame_prev,
/*aSrc1Desc*/ frame_cur,
/*aCoor0Desc*/ features_prev,
/*aCoor1Desc*/ features_cur,
/*aCoor1Desc_O*/ features_out,
/*aMaxCorners*/ CORNERS_MAX,
/*aW*/ frame_cur.cols, /*aH*/ frame_cur.rows, /*aPyrLayers*/ 4, /*aBoxSize*/ 7, /*aNumIter*/ 10, /*aReqPadding*/1
);
apex_processor.Process();
