1. A sewing machine, comprising: a creating portion that creates a projection image, the projection image including a characteristic point and being configured to be projected onto a sewing object; a projecting portion that is configured to project onto the sewing object the projection image created by the creating portion; an image capture portion that is mounted in a position being different from a position of the projecting portion and that is configured to create a captured image by image capture of the characteristic point projected by the projecting portion; and a computing portion that is configured to compute a thickness of the sewing object based on: (i) the projection image created by the creating portion, (ii) the captured image created by the image capture portion, (iii) an internal variable and an external variable for the projecting portion, and (iv) an internal variable and an external variable for the image capture portion.