"Not enough points to align" during aglin chunk

[feiko.lai]

Agisoft v1.3
3 Chunks, in totally ~ 6600 images, all are aligned, dense cloud and mesh generated.

Align chunk:
Method: point based, Accuracy: low, Point limit: 80000, Preselect image pairs: enabled

Log:

Code: [Select]

17-02-20 16:57:28 photo 6653/1: 9989 points
2017-02-20 16:57:29 photo 6654/0: 9053 points
2017-02-20 16:57:30 photo 6654/1: 10195 points
2017-02-20 16:57:31 photo 6655/0: 9053 points
2017-02-20 16:57:31 photo 6655/1: 10408 points
2017-02-20 16:57:32 photo 6656/0: 9404 points
2017-02-20 16:57:33 photo 6656/1: 10638 points
2017-02-20 16:57:34 photo 6657/0: 9372 points
2017-02-20 16:57:35 photo 6657/1: 10805 points
2017-02-20 16:57:36 photo 6658/0: 9033 points
2017-02-20 16:57:37 photo 6658/1: 10500 points
2017-02-20 16:57:37 photo 6659/0: 8933 points
2017-02-20 16:57:38 photo 6659/1: 10479 points
2017-02-20 16:57:39 photo 6660/0: 8966 points
2017-02-20 16:57:40 photo 6660/1: 10558 points
2017-02-20 16:57:41 photo 6661/0: 8725 points
2017-02-20 16:57:42 photo 6661/1: 10097 points
2017-02-20 16:57:43 photo 6662/0: 8294 points
2017-02-20 16:57:43 photo 6662/1: 9787 points
2017-02-20 16:57:44 photo 6663/0: 7519 points
2017-02-20 16:57:45 photo 6663/1: 9171 points
2017-02-20 16:57:46 photo 6664/0: 7525 points
2017-02-20 16:57:47 photo 6664/1: 9392 points
2017-02-20 16:57:48 photo 6665/0: 7686 points
2017-02-20 16:57:48 photo 6665/1: 9606 points
2017-02-20 16:57:49 photo 6666/0: 7802 points
2017-02-20 16:57:50 photo 6666/1: 10151 points
2017-02-20 16:57:51 photo 6667/0: 7563 points
2017-02-20 16:57:52 photo 6667/1: 10022 points
2017-02-20 16:57:53 photo 6668/0: 7457 points
2017-02-20 16:57:54 photo 6668/1: 9646 points
2017-02-20 16:57:54 photo 6669/0: 7763 points
2017-02-20 16:57:55 photo 6669/1: 9540 points
2017-02-20 16:57:56 photo 6670/0: 8111 points
2017-02-20 16:57:57 photo 6670/1: 9614 points
2017-02-20 16:57:58 photo 6671/0: 8128 points
2017-02-20 16:57:59 photo 6671/1: 9976 points
2017-02-20 16:57:59 photo 6672/0: 7917 points
2017-02-20 16:58:00 photo 6672/1: 9594 points
2017-02-20 16:58:01 photo 6673/0: 7850 points
2017-02-20 16:58:02 photo 6673/1: 9312 points
2017-02-20 16:58:03 photo 6674/0: 7505 points
2017-02-20 16:58:04 photo 6674/1: 8924 points
2017-02-20 16:58:04 photo 6675/0: 7201 points
2017-02-20 16:58:05 photo 6675/1: 8906 points
2017-02-20 16:58:06 photo 6676/0: 7771 points
2017-02-20 16:58:07 photo 6676/1: 9122 points
2017-02-20 16:58:08 photo 6677/0: 7706 points
2017-02-20 16:58:09 photo 6677/1: 8837 points
2017-02-20 16:58:10 photo 6678/0: 7727 points
2017-02-20 16:58:10 photo 6678/1: 8691 points
2017-02-20 16:58:11 photo 6679/0: 7906 points
2017-02-20 16:58:12 photo 6679/1: 8937 points
2017-02-20 16:58:13 photo 6680/0: 8024 points
2017-02-20 16:58:14 photo 6680/1: 9340 points
2017-02-20 16:58:15 photo 6681/0: 7599 points
2017-02-20 16:58:15 photo 6681/1: 8837 points
2017-02-20 16:58:16 photo 6682/0: 6995 points
2017-02-20 16:58:17 photo 6682/1: 8507 points
2017-02-20 16:58:18 photo 6683/0: 7534 points
2017-02-20 16:58:19 photo 6683/1: 8809 points
2017-02-20 16:58:20 photo 6684/0: 8367 points
2017-02-20 16:58:20 photo 6684/1: 9416 points
2017-02-20 16:58:21 photo 6685/0: 8555 points
2017-02-20 16:58:22 photo 6685/1: 10121 points
2017-02-20 16:58:23 photo 6686/0: 9007 points
2017-02-20 16:58:24 photo 6686/1: 11118 points
2017-02-20 16:58:25 photo 6687/0: 9093 points
2017-02-20 16:58:25 photo 6687/1: 11405 points
2017-02-20 16:58:26 photo 6688/0: 9801 points
2017-02-20 16:58:27 photo 6688/1: 12599 points
2017-02-20 16:58:28 photo 6689/0: 9705 points
2017-02-20 16:58:29 photo 6689/1: 12887 points
2017-02-20 16:58:29 points detected in 10309.1 sec
2017-02-20 16:58:29 Selecting pairs...
2017-02-23 02:07:58 229420568 matches found in 205767 sec
2017-02-23 02:09:38 matches combined in 98.658 sec
2017-02-23 02:10:17 20102 of 20102 pairs selected in 0.011 sec
2017-02-23 02:10:17 Matching points...
2017-02-23 02:38:42 35817483 matches found in 1705.51 sec
2017-02-23 02:38:48 matches combined in 5.608 sec
2017-02-23 02:38:48 finished matching in 217929 sec
2017-02-23 02:38:48 setting point indices... 6529182 done in 9.29 sec
2017-02-23 02:39:04 generated 6529182 tie points, 2.68849 average projections
2017-02-23 02:39:07 removed 61750 multiple indices
2017-02-23 02:39:07 removed 3390 tracks
2017-02-23 02:39:35 adding 2443099 points, 513 far (10 threshold), 5 inaccurate, 708 invisible, 113 weak
2017-02-23 02:39:37 adding 1167769 points, 469 far (10 threshold), 6 inaccurate, 877 invisible, 50 weak
2017-02-23 02:39:39 adding 871752 points, 434 far (10 threshold), 2 inaccurate, 762 invisible, 47 weak
2017-02-23 02:39:39 Aligning groups by 299038 points
2017-02-23 02:39:39 iteration 0: 112330 points, 0.00360861 error
2017-02-23 02:39:39 iteration 1: 110267 points, 0.0034801 error
2017-02-23 02:39:39 iteration 2: 109738 points, 0.00345292 error
2017-02-23 02:39:39 iteration 3: 109584 points, 0.00344514 error
2017-02-23 02:39:39 iteration 4: 109535 points, 0.00344259 error
2017-02-23 02:39:43 Not enough points to align
2017-02-23 02:39:43 Not enough points to align
2017-02-23 02:39:45 Finished processing in 217987 sec (exit code 1)


It takes me 3 days to finish align chunks and after that I saw logs above. Does the line "Not enough points to align" matter? Do I need to run it with higher accuracy?

[Alexey Pasumansky]

Hello feiko.lai,

If the chunks are accurately referenced in the same coordinate system, you do not need to run chunk alignment operation. They should be already aligned in the same coordinate system space.

[Yoann Courtois]

Hello !

I have the same problem on smaller project where I would like to align small chunks (several m2) on a big georeferenced one (2000m2).
As I explain in other topics, my main chunk is georeferenced based on GNSS point, and smaller chunks don't have any one them, so I have to align them on the main one in order to make measurements.
But sometimes, when I use "Align Chunk" tool, I get the same problem as feiko.lai, that "Not enough point to align".
 
After some random test, I finally found that the problem seems to come from the Preselect image pairs. When it's enable, I get "Not enough point". But if I desable it, it works !!! (several tests have shown the same result).

My question to Alexey is then: How the "preselect image pairs" work ? May it is too strict and reduce the image pairs too much so that the alignment cannot be done ?

[Alexey Pasumansky]

Hello Yoann,

Image pair preselection is trying to find overlapping photos using their downsampled copies. If the number of found matching point for such low-resolution images is below some threshold the pair will not be considered as overlapping for the full-size matching.

[Yoann Courtois]

Thanks for those details.

So it seems the threshold is a bit too high. Because the alignment doesn't give any result when using the low-resolution preselection, whereas everything looks fine when the preselection is disabled.