The octree node it's in is made of 8 voxels and a bit to store whether the thing contains anything at all. That's one bit per voxel plus one per 8. 1 + 1/8 = 1,125. Add another parent node with 7 siblings and you get 1 + 1/8 + 1/8/8 = 1,140625. Suspiciously close to the 1.15 they mentioned.
roscpp is a C++ implementation of ROS. It provides a client library that enables C++ programmers to quickly interface with ROS Topics, Services, and Parameters..