1. Draw a 90-degree arc with grass, draw a circle perpendicular to the end of the arc, and use the scanning tool to select a fixed direction (perpendicular to the circular direction of the cross section). The ratio is linear, starting from 1 and ending at 2.

2. Draw two circles at both ends perpendicular to the circular arc, select two circles and two sections for the cross section with the scanning tool, and pay attention to the consistency of the starting positions of the two circles.