Middle school students would perceive the global-first topological invariance of the solid figure when they make the projection, and then the local property or components.
中学生在进行几何体射影时首先要把握几何体的大范围拓扑性质，然后才是物体的局部性质或组成部分。
2
The features achieve partial invariance to local variations, such as affine or 3D projections, by blurring image gradient locations.