| Invariant Features from Interest Point Groups Recent countries visiting this post |  |
 | 7 | United States |
 | 3 | |
 | 1 | Japan |
 | 1 | Taiwan |
 | 1 | Australia |
| Invariant Features from Interest Point Groups Recent countries visiting this post | |
| 7 | United States |
| 3 | |
| 1 | Japan |
| 1 | Taiwan |
| 1 | Australia |