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Author Topic: Alignment step add-on  (Read 337 times)

Yoann Courtois

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Alignment step add-on
« on: October 25, 2017, 10:25:07 AM »
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
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           Yoann COURTOIS
Engineer in Geodesy, Cartography & Surveying ( graduated from INSA Strasbourg, FRANCE )
Topographic engineer in ALTEA Experts, special. in Photogrammetric survey methods ( Lyon, FRANCE )
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GeoGecco

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Re: Alignment step add-on
« Reply #1 on: January 21, 2018, 09:18:50 PM »
+1

Alexey Pasumansky

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Re: Alignment step add-on
« Reply #2 on: January 21, 2018, 10:49:16 PM »
Hello Yoann,

Do you have "Keep key points" option turned on in the Advanced preferences tab prior to the initial alignment?
Best regards,
Alexey Pasumansky,
AgiSoft LLC

Yoann Courtois

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Re: Alignment step add-on
« Reply #3 on: Today at 04:43:15 PM »
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
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           Yoann COURTOIS
Engineer in Geodesy, Cartography & Surveying ( graduated from INSA Strasbourg, FRANCE )
Topographic engineer in ALTEA Experts, special. in Photogrammetric survey methods ( Lyon, FRANCE )
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Alexey Pasumansky

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Re: Alignment step add-on
« Reply #4 on: Today at 05:26:41 PM »
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?
Best regards,
Alexey Pasumansky,
AgiSoft LLC

Yoann Courtois

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Re: Alignment step add-on
« Reply #5 on: Today at 06:06:29 PM »
Hum, has something changed in last realease ?

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

Regards
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           Yoann COURTOIS
Engineer in Geodesy, Cartography & Surveying ( graduated from INSA Strasbourg, FRANCE )
Topographic engineer in ALTEA Experts, special. in Photogrammetric survey methods ( Lyon, FRANCE )
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Alexey Pasumansky

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Re: Alignment step add-on
« Reply #6 on: Today at 06:32:04 PM »
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.
Best regards,
Alexey Pasumansky,
AgiSoft LLC

Yoann Courtois

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Re: Alignment step add-on
« Reply #7 on: Today at 06:46:43 PM »
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
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           Yoann COURTOIS
Engineer in Geodesy, Cartography & Surveying ( graduated from INSA Strasbourg, FRANCE )
Topographic engineer in ALTEA Experts, special. in Photogrammetric survey methods ( Lyon, FRANCE )
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