Most coordinate systems are absolute in nature. This means that 1 meter is always 1 meter. If you plot a point at 0.2 inches by 1.7 inches on a graph, you know the distance will be 1.5 inches. As previously explained, there are a lot of benefits of absolute measurement systems. However, without a way to measure in absolutes on a large scale and convert that to a mobile digital system, Microsoft had to find a different solution.

Some systems are relative, which means that they plot positions in relationship to other objects in the system; this type of system works better on a larger scale.

World Anchors or spatial anchors use a coordinate system that is primarily relative. With the HoloLens, the sensor array is always working, though it can be less than accurate at times. Lighting, the color of your fixtures, and furniture affect the scanning process. Sometimes, things get moved around and changed, and this can factor into the process as well.

World Anchors use the mesh generated from the spatial mapping process to determine the relative positions of items. However,they also use the other holograms in the area as points of reference, using your position for priority. In other words, if you put one hologram in your living room near your couch, the mesh data that makes up that general area of the spatial map is used as the reference for that hologram's placement.

Now, if you go and place five more holograms, they now all have parts of the mesh they are using for relative positioning information, but are also now looking at the position of the other objects in the area.

The closer the holograms are to the user determines their priority to accuracy. If changes in the Spatial Mapping happen and lead to the need to shift positions, generally the major shifts will happen farther away from the user.