Schematic illustration of the projected geometry of an inclined multi-ringed circum-stellar disk (this also holds for continuous disks). When viewed at an inclination angle i, the disk's intrinsically (and assumed) circular structure appears elliptical due to projection. The offset u between the star position and the centre of the ellipse arises from the projected height of the disk surface along the semiminor axis. This geometric offset becomes observable in scattered-light images and is used to infer the disk height structure.