Alignment Troubleshooting

Development World Creation
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1

I need help with aligning components.  I’m running into the same alignment problems again and again:

I’m aligning aerial drone shots (gps georeferenced) with eye-level camera shots (not referenced).  Out of 500 shots I get 20+ components, most with 5 or less photos.

I start by picking 5 or so clearly identifiable points in the biggest component on 3-5 photos that have the most matches.   Then I go to the next smallest component and try to find the same points in a few images.  As I go along, if I can’t find 3 points, I add more points…

Eventually, I will run across an image with many identifiable points, but any point mark will report huge amounts of error (>10 px) and I am stuck!  Or, I will start getting control point suggestions that are way off the mark. And, if I reconstruct the scene, I will often get misaligned parts floating through my scene…

What is the workflow for dealing with misaligned components? Should I delete the bad components and realign the scene? How do I identify which component is the problem?  I can see which photos are misaligned by the bad suggested CPs and by using the 3D control point mode on parts that look bad to see which photos they’re coming from, but how do I find out which components a photo is a member of?

Thanks for your help!

-Donald 

2

it seems that you need to fine-tune the placement of control points (make it more precise) to lower those errors,

as for the components, here is one official tip: https://support.capturingreality.com/hc/en-us/articles/115001485012-How-to-put-together-more-components-,

to see the images forming a component, you can navigate to the 1Ds window and expand Component / Camera poses

3

My experience has been that you need to massage the settings and control points changing them and adjusting through multiple alignments and sometimes deleting components and sometimes trying to merge a few together. It’s an iterative process.

4

Lucia and Steven, 

Thanks!  I don’t think the errors are from the placement of control points.  I have a model with 15 CPs all within 2 px, but in certain photos placing those same points causes the error to get huge. “>10 px” is on the low end of what I see – the errors go from 10 to 1000 pixels. 

I have tried deleting the components where those photos had been registered and re-aligning, but the issue keeps coming back.  Next thing I’ll try a different way of merging them in components… iterations.  

Also, can anyone tell me if there is an easy way to find out which components a photo is being used in?

Thanks again!

-Donald

 

 

5

then you can start removing the control points with the largest errors one by one, often removing just one of them resolves the issues with others though; if you keep getting lots of components, it is usually an overlap matter