myMat.at<unsigned short="">(row,col) += 1
Why is that operation so slow? Why is that slower than increasing an INT (or 100 INTs for that matter) for example? If I want to make a lot of this type of calls, what would be the most efficient way?
It is slower because it had to do more work. Not just increment the value of INT. First it to need to use row and col to calculate place in memory that should be incremented. It also need to access value in array. Random access to values in arrays is time consuming task. Read this tutorial for short review of how pixels of Mat should be accessed.
So it is the Random Access part that makes it so time consuming? I am building up a projection of an image with range data by taking every range data and transforming that into a row&col and adding 1 to myMat which represents the floorPlane. i.e, a wall will be a bright line. Maybe there is a faster way of achieving the same result?
I am not sure I understand correctly what you are trying to achieve, but calculation of projection is usually an expensive process, so random access will not be the most time consuming part.
Please, read the proposed tutorial. It explains the theme perfectly.
Asked: 2012-12-19 09:25:16 -0600
Seen: 1,918 times
Last updated: Dec 19 '12
