| 315 | | Place tie points on the higher altitude lines only when you're really sure of them - they will always have a greater error due to the pixel size. |
| 316 | | |
| | 317 | * Better to have fewer good tie points than many bad ones |
| | 318 | * Focus mainly on the lower altitude lines |
| | 319 | * Place tie points on the higher altitude lines only when you're really sure of them - they will always have a greater error due to the pixel size. |
| | 320 | * Tarmac roads are good, but: |
| | 321 | * avoid paint on road (intensity problems and height difference) |
| | 322 | * choose continuous homogeneous areas |
| | 323 | * Avoid: |
| | 324 | * building corners (perspective) |
| | 325 | * grass (multiple returns, moves) |
| | 326 | * cars/people (moves) |
| | 327 | * areas with streaky intensity (likely to have ranging errors) |
| | 328 | * Try to select areas where you can use the nearby geometry to help you |
| | 329 | * e.g. follow straight road edges to where they intersect another feature, so you have more than just one pixel to guide you to the intersection point in other images |
| | 330 | * avoid using building edges (perspective shifts) |
| | 331 | * Location of tie points |
| | 332 | * Focus mainly in the core intersection area |
| | 333 | * Points around nadir |
| | 334 | * Points around the edges of the swath |
| | 335 | * Some generally scattered around |
| | 336 | * Some outside the core intersection area |
| | 337 | * Try to include some on slopes(?) |