摘要
应用正投影理论，研究了第三角投影向第一角的转换。给工程实际提供一种迅速而准确的方法，用来解决国际技术交流中图样的障碍。
The theory of right angle projection was employed to study the conversion of projections in the third quadrant to the first quadrant.The resultant method obtained is accurate and convenient,and can be practically used to overcome the obstacles in the communications of engineering drawings between different countries that use projections in different quadrants.
