Draw a vertical line perpendicular to the bottom surface (that is, the ground) and a horizontal line parallel to the bottom surface, and then draw a line on the whole cambered surface. Pay attention to the density of line drawing. The closer to the convex or concave part of the arc, the greater the density of drawing lines, that is, the denser the lines are drawn from both sides to the middle. The above is a black and white line drawing. If it is colored, it can be drawn as a cylinder to show the difference between light and backlight.