I read the article but didn't watch the videos yet, but I'm curious as to what would be needed to make this a 3D map. That is, I'm assuming this 2D map records the position of all of these objects in the sky, but not the distance from Earth. But I thought that calculating the distance of objects is relatively straightforward, e.g. you hear all the time "Galaxy X is 2 billion lightyears away" or whatever. Would it just be really computationally expensive to calculate the distance to all of the 4 billion objects identified in the map?