Question

Using C++ (and Qt), I need to process a big amount of 3D coordinates.

Specifically, when I receive a 3D coordinate (made of 3 doubles), I need to check in a list if this coordinate has already been processed. If not, then I process it and add it to the list (or container).

The amount of coordinates can become very big, so I need to store the processed coordinates in a container which will ensure that checking if a 3D coordinate is already contained in the container is fast.

I was thinking of using a map of a map of a map, storing the x coordinate, then the y coordinate then the z coordinate, but this makes it quite tedious to use, so I’m actually hoping there is a much better way to do it that I cannot think of.

Answer 1

Probably the simplest way to speed up such processing is to store the already-processed points in Octree. Checking for duplication will become close to logarithmic.

Also, make sure you tolerate round-off errors by checking the distance between the points, not the equality of the coordinates.