Examples disclosed herein describe, among other things, a computing system. The computing system may in some examples include a touch-sensitive surface, a display, and at least one camera to capture an image representing an object disposed between the camera and the touch-sensitive surface. The computing system may also include a detection engine to determine, based at least on the image, display coordinates, where the display coordinates may correspond to the object's projection onto the touch-sensitive surface, and the display is not parallel to the touch-sensitive surface. In some examples, the detection engine is also to display an object indicator at the determined display coordinates on the display.