I have this code:
mapx.create(image.size(), CV_32FC1);
mapy.create(image.size(), CV_32FC1);
what is the values in the mapx and mapy after this? Are all data is zero?
what about this type of initialization:
cv::Mat mapx(image.size(), CV_32FC1);
Do I need explicitly set the value of each element to zero?
How can I set the value of each element to say -1?
Data after create should be undefined. In fact, your are just allocating memory.
cv::Mat mapx(image.size(), CV_32FC1);
is exactly as
cv::Mat1f mapx(image.size());
and
cv::Mat mapy;
mapy.create(image.size(), CV_32FC1);
You can assign an initial value (e.g. -1) like this:
cv::Mat1f(images.size(), -1.f);
Regarding you main question Should I initialize a cv::Mat, the answer is that in general you don't need to. From OpenCV doc:
Instead of writing:
Mat color;
...
Mat gray(color.rows, color.cols, color.depth());
cvtColor(color, gray, CV_BGR2GRAY);
you can simply write:
Mat color;
...
Mat gray;
cvtColor(color, gray, CV_BGR2GRAY);
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