ok, let's open this thread for other nicer pictures by solving what the picture above
both parts of the image, left and right, are showing the data of a CT Scan of a teddybear. on the left only some parts are shown to anything at all according to their position in space. the right side shows the probability of voxels over the overall density shown on the y axis and the length of the gradient on the x axis. the squares there directly correspond to the colors on the left side, i.e. only the voxel inside such squares are drawn, all others are ignored.