TiltBrush by Google
Not exactly the same thing but I've actually been sitting on an idea for a mobile app that was inspired by Google: Essentially, you'd be able to look through your phone camera and draw on the world on the screen. Then other people could see your geolocated creations and maybe modify them. (I also considered autodecay for dense areas) I never did figure out the physics of how the projection would work or if the accuracy of GPS made it feasible, but I thought it'd be a good way to blend our real world and allow a sort of "virtual graffiti", a form of augmented virtual reality. As with all interesting ideas though, if you wait too long, someone comes and does it and I saw something similar on HN except with stickers also. As for how Google inspired it, their photo app lets you physically rotate your phone to pan around photospheres.TiltBrush seems more of a pure creative endeavor meant for artists or anyone just looking to mess around a virtual world. I really much like how you can walk around the creation/space. The fact that it's three dimensional actually makes it more like sculpture than painting, though I"m sure there isn't anything other than parallax errors preventing 2D drawing. The granularity of the brushes seems to be good, so it will all come down to how well the hand controllers will work together with the headset. (hopefully not requiring surgery-like stillness just to get small details right, maybe by allowing adjustable head movement sensitivity)