Shipwreck: marker-based chunk align

[ThomasVD]

Hi everyone!

I'm wondering whether after performing marker-based chunk alignment the chunks can be merged and the markers then used in order to "optimize" the merged sparse point cloud (like you would if you had ground control points)?
In fact, is there any way to benefit from using the "optimize" function without having ground control points?

The project I'm working on is a shipwreck site. Due to low visibility we had to get very close to the wreck while taking pictures, which in turn meant we had to use a LOT of pictures in order to have sufficient overlap to cover the entire site. In total about 7000 pictures are used, divided into several chunks (see screenshot). These chunks have been aligned (after meshing each chunk and generating a texture on which features were then picked) using marker-based alignment. However not every chunk fits perfectly onto the next one (very slight differences in geometry which cause the markers to not align perfectly). Therefore I would like to somehow optimize the final merged model so that the geometry does align 100%.

Any advice / suggestions on workflow are very much appreciated!
Thank you,

Thomas

[igor73]

Any particular reason why you divide up in chunks for alignment?    Not enough RAM? 

[ThomasVD]

Divided into chunks the images take a lot less time to process + if you added all 7000 pictures at once they'd be unlikely to all align correctly since the images were captured over the course of several days, meaning there's slight variations (such as different pieces of debris or sand lying on top) between different chunks.

[ThomasVD]

Edit: think this post by gEEvEE more or less answers my question: http://www.agisoft.com/forum/index.php?topic=738.msg15175#msg15175 , thanks!