Aligning chunks

[skantron]

I have a building I took photos of, and am having trouble with getting all the photos aligned.  There are about 200 photos all together, and if I try to align them all at once, the sparse point cloud has the front and the back of the building overlapped.  If I put the front and the back into separate chunks, the cameras align fine within their chunks, but then I can't get the two separate chunks to align. IF I run the align chunks tool, they line up the same way that the points line up if I do them all in one batch.  I've had issues like this with other models especially ones that may have mostly symmetrical sides.  I am wondering if there is something incorrect or that I am missing as I take photos, or if there is anything I can to help align the two chunks together...  If there is information I can share that share, I will be happy to do so.  I am using Agisoft Photoscan Standard.

Thanks in Advance.

[Alexey Pasumansky]

Hello skantron,

How you were shooting the object, is there's the same background for front and back sub-sets that is causing the invalid matching points during camera alignment?

[skantron]

Hi, heres some screenshots of the different chunks, I hope this makes it clearer.  I have most everything that is not the building masked out.  I was using a drone and scaling the building in vertical stripes around the building.  Thanks for looking into this.

[skantron]

Is there any more information I can provide? 

Thanks

[Airborne]

I'm actually pretty new to this as well but since I'm in a similar predicament I thought I'd ride the wave. I flew a large roof inspection yesterday in 3 flights. Appended them so I now have 3 chunks. I just finished aligning the first chunk then realized I can align multiple chunks.

Question 1: Can align each chunk individually at this point then merge them?

Question 2: Do I have to align all 3 chunks right from the start then merge them?

Question 3: Or once I have aligned photos individually for all three chunks do I then align the chunks and merge them?


To explain a little more, the first flight (166 cameras) was flown horizontally or the full length of the building. The second (111 cameras) and third (70 cameras) flights I ran widthwise. I ran out of battery halfway through the second flight hence the third.

Photoscan Pro

Any input would be greatly appreciated! I hope I'm not hijacking the thread...

Jason

[Steve003]

I also would love to know more about Align chunks and see no one has explained such in your question.
Merge chunks simply brings the photo sets together. If one chunk has three faces of a building , face 1 2 and 3 and another chunk faces 3 and 4 is one face in common enough ?
I often have to photo an object then turn it upside down to do the underside, and such sees one side re-photographed, so agisoft needs to align that side with the same side in chunk 1. My METHOD D drawn up with Alexie's help doesnt mention using align chunks at all, the merged chunks all have masks from model so I guess agisoft is not aligning chunks but merely seeing a masked photo with faces 3 and 4, and another with faces 1 2 and 3 and bringing them together when making the dense point cloud., however my projects such as this all fail.

They work if the object isn't moved. so far anything I have done fails.

would align chunks stop that failure I wonder.

Steve003

[Steve003]

anyone ?

[Kiesel]

Hi Steve003,

have look at tutorials by Heinrich Mallison, for example this one: https://dinosaurpalaeo.wordpress.com/2015/10/11/photogrammetry-tutorial-11-how-to-handle-a-project-in-agisoft-photoscan/


He is using an one chunk technique

I do not use separate chunks if I can help it. Rather, I try to make sure that all my photos show my specimen with a totally immobile background, or one that has no features at all, across all sets of photos I take. This means, for example, that if I need to flip a specimen over to photograph the underside, I move it to a different location, so that the two background are totally different from each other. This way, the only correlating features between the first set of photographs of the upper side of the specimen) and the second set (showing the underside) are all on the specimen itself. If needs be, I use more than two locations to create more sets of images.

Hope this helps.

Regards

Kiesel