Alignment step add-on

[Yoann Courtois]

Hi !

With the 1.4 pre-release, I've noticed it's now possible to easily add pictures to a georeferenced chunk and align them without reset the current alignment, which is a great tool.

But, it would be nice if those new tie points would be added to the previous tie point cloud instead of being substitute to it.
Indeed, it would allowed to optimize the model after adding those pictures, which is not possible for now.

Regards

[GeoGecco]

+1

[Alexey Pasumansky]

Hello Yoann,

Do you have "Keep key points" option turned on in the Advanced preferences tab prior to the initial alignment?

[Yoann Courtois]

Hello Alexey !

Yes yes, I have turned on this option, which well accelerate the process when adding a few pictures to a big project. But I wasn't talking about that.

I meant, it would be good if the first main tie point cloud would be stored somehow so that we could use the "Optimize" tool after other pictures were aligned on the main model.
Explained with a example :
- A first main model (1 000 pictures) is composed of 1 000 000 tie points, which linked those 1 000 pictures together.
- A subset of pictures (50 pictures) is added afterwards and aligned on the main model. Then the cloud is composed of, let's say 50 000 tie points, which linked those 50 pictures together, and those 50 pictures with some of the 1 000 first pictures. BUT, we have lost the 1 000 000 tie points which linked the 1 000 pictures together ! Then it's not possible to "Optimize camera" !

It would be so nice if those 1 000 000 tie points who be kept, so that after subset alignement we get 1 040 000 tie points (I supposed 10 000 (out of 50 000) tie points existed already beforewards).

Is it sufficiently clear ? 

Regards

[Alexey Pasumansky]

Hello Yoann,

Incremental image alignment shouldn't remove existing matching points.

Are you sure that you have checked on Keep Key Points option in the Advanced preferences window before the initial alignment is started?

[Yoann Courtois]

Hum, has something changed in last realease ?

I will test that again in my next project, and give you news !

Regards

[Alexey Pasumansky]

Hello Yoann,

If you do not have key points from the initial alignment, then you'll lose the tie points from that alignment - key points will be detected for all the images, but the tie points would have at least one projection on the newly added photos.

In case you have key points kept from the initial alignment, the tie points wouldn't be lost.

[Yoann Courtois]

Ok perfect ! Just noticed the previous point cloud didn't disappear when starting subset alignment !
We now will be able to Optimize afterwards !

The next step would be to give the possibility to lock one or several camera positions during model optimization. Indeed, as we don't use georeferenced images (or not enough accurate georeferencement), we cannot force the position with camera accuracy.
One solution would be to copy/paste images coordinates, from estimated (where it's actually not possible to "copy") to source, and set a tiny camera accuracy so that those pictures won't move. It would be easier to add a "padlock" tool on one or a set of picture. You see ?

Regards

[Yoann Courtois]

Hello Alexey !

Is there any possibility to remove key points from the project afterwards ? Wasn't able to find where to do that !

Regards

[Alexey Pasumansky]

Hello Yoann,

Currently there's no option to remove the key points, but we are planning to implement that in one of the upcoming updates.

[Yoann Courtois]

Hi Alexey !

I noticed you've released 1.4.1 update ! Unfortunately, I didn't find anything about removing key points !
Is this option delayed ?

Regards

[Alexey Pasumansky]

Hello Yoann,

The option is not included in the 1.4.1 update. We are planning to implement this functionality in the later updates, so that information about the key points presence would be included in the Workspace pane and the options to remove key points and duplicate with the chunk would be also provided.

[Yoann Courtois]

Thanks for your fast reply, as usual !

Would be also good to be able to view key points on pictures.
But at first, to be able to remove key points for project archiving is really needed. Indeed, as an example on my last project, tie points archiving (needed) represent 300Mo of data, whereas key points archiving (not needed) represented more than 12Go !

Regards

[Yoann Courtois]

Hi Alexey,

Despite it's impossible to delete key points inside PhotoScan, would it be possible to directly delete it from the project folder ?

Indeed, when I go though my project.files/chunk/point_cloud, I see 3 zip folders :
- points_cloud.zip, which looks to be the tie points folder.
- points0.zip, which is veeeeeery massive in memory.
- points1.zip, which is about the same size of the first folder.

Those two last zip folders contain .kpt files... which looks to be about key points.

I try to create a copy of everything and delete points0.zip, no error message when I opened the project.

What do you think about ?

Regards

[dcobra]

I'm also quite interested in deleting key points and am wondering if I can just delete the points0.zip folder without and issues.  Has anyone had any success or have any advice?