Aligning chunks workflow

[igor73]

I hace a very large arbitrary project of some 5000 images.  I have split this up in to 4 chunks before aligning.  It is a monumental task processing this and a chunk of 1000 images takes around 30-35 hours to align  on High setting and generic off. 

The disappointment is that aligning chunks does not seem to save any time at all really.  Aligning 2 chunks takes about 50 hours, nearly the same time.  Pre select imaged pairs is turned off , high setting, 40 000 points..  I had to divide up in chunks because Agisoft failed completely to align when i tested aligning 5000 images in one single chunk, only 3 images out of 5000 aligned.    Now splitting the project up in chunks in a  logical manner Agisoft aligners everything very well. Last chunk every single image of more than 1000 images aligned. 

How can i make the align chunk faster?  Obvious options to consider would be changing accuracy to medium and enable image pairs.  Will this effect accuracy a lot? 

Camera align is super fast but the problem here is that i did not include any cameras from neighboring chunks in the chunk so this will not work.  Maybe that would have been the best way?  Any way i can add cameras from another chunk to an already processed chunk? 

[Wishgranter]

Hi Igor, the images are with GPS coordinates or ?

[James]

Sorry I can't help, there is no way to add images to an already aligned chunk without aligning the whole lot again.

When working with chunks like this, it is a good idea to include cameras at the 'boundary' between chunks in each chunk, not only so that you can use the camera align method, but also because aligning chunks by points will not generate new tie points/sparse cloud points, so you would be missing out on potential data at the boundary between chunks.

I assume you are not using the Pro version otherwise you could just add a few markers and align that way very quickly? I'm not sure if the trial version of Pro will allow you any saves these days?

[igor73]

Wishgranter-   no GPS coordinates. 

Yes that is what i figured.  I should have added cameras on the borders so camera alignment would have worked.  To late now.   But maybe i can add cameras to the chunk from bordering chunk  and select them and click align?  I am only at the sparse point cloud stage so this will not destroy any dense cloud. 

Could re-process but already over 100 hours in to aligning now so that would be frustrating  I can always merge the models in Zbrush but it would have to be done manually so accuracy would suffer.

So my best option is to upgrade to pro version?  Will  manually placing markers and do marker based alignment be as accurate as camera based alignment?

Point based alignment is the same thing as doing completley new Alignment on all my chunks then?  Don´t get the point of the point based alignment in that case 

[igor73]

Also i have already used up 30 days of trial on Pro last year so i think i can´t get aces to  it again. 

[James]

How about this?

Create another chunk containing just 'a few' overlapping images from a pair of your existing adjacent large chunks, and align.

Then you should be able to align the two big chunks with the one small chunk using camera based alignment.

Repeat as necessary to get a full set of aligned chunks.

Accuracy should increase with the number of small chunks, and the number of images in each small chunk, but it might be enough for your requirements without doing too much work?

Regarding whether marker based alignment is as accurate as camera based alignment, i guess it depends on the distribution of cameras, and accuracy of your markers, so who knows!

[igor73]

James, i think you may be a genius!  This might work, will try it!  Thanks for the tip!