Forum

Author Topic: What does Optimize Cameras actually do?  (Read 8302 times)

peteforde

  • Newbie
  • *
  • Posts: 4
    • View Profile
What does Optimize Cameras actually do?
« on: April 02, 2015, 12:52:10 AM »
Hi all,

I am reconstructing models of humans captured from a 60-camera cylindrical rig.

Registration seems successful - all of the cameras appear to be hovering and pointing where I expect them to be.

What confuses me is the existence of the Optimize Cameras command; optimization is a good thing, so it must be good, right? :)

Seriously, it doesn't appear to make significant changes to the placement of the cameras. And if optimization of cameras is a good thing, why doesn't it happen by default?

I actually did RTFM and the explanation was a bit opaque to people who don't intuitively know what it might do doing.

Could anyone take a crack at a simple explanation?

If I compared the camera exports of optimized and non-optimized cameras, how would they be different?

aggieair

  • Jr. Member
  • **
  • Posts: 93
    • View Profile
Re: What does Optimize Cameras actually do?
« Reply #1 on: April 02, 2015, 12:57:33 AM »
I use the Optimze Cameras after I've aligned photos using flightlog location info, and added GPS aerial target coordinates to tie down my image even more.  I optimize and it changes the solution where I have to redo my point cloud based since it will be based on GPS targets instead of coarse flightlog data. 

But not sure how it's used if you don't have camera locations or GPS locations, hopefully someone can answer that here ...  (Just an example of how I use it.)

JohnyJoe

  • Jr. Member
  • **
  • Posts: 62
    • View Profile
Re: What does Optimize Cameras actually do?
« Reply #2 on: April 03, 2015, 09:58:14 PM »
isnt it somehow dependent also on your physical camera calibration done with agisoft lens? (or is it a wrong thought?)

peteforde

  • Newbie
  • *
  • Posts: 4
    • View Profile
Re: What does Optimize Cameras actually do?
« Reply #3 on: April 07, 2015, 08:05:41 AM »
Honestly, you could be right or wrong - but there's no documentation and I cannot find anything resembling an official comment.

Marcel

  • Sr. Member
  • ****
  • Posts: 309
    • View Profile
Re: What does Optimize Cameras actually do?
« Reply #4 on: April 07, 2015, 10:28:53 AM »
As far as I know, Optimize Cameras re-aligns the cameras based on the points in the Sparse Cloud*.

This is useful in combination with Gradual Selection: first you remove inaccurate points from the Sparse Cloud and then you re-align the cameras. The result should be a more accurate alignment of the cameras.

If you have a good alignment to begin with, you will probably not see a change in the positions or angles of the cameras. This is because a good alignment already has a very high accuracy (the same point viewed through two different cameras might only be offset by a single pixel, or even less). But for Depth Reconstruction at High or Ultra quality it might still be useful to Optimize the alignment (if your alignment is inaccurate it can lead to noise in the Dense Cloud).

* it probably also does some other stuff like optimize lens distortion correction. Compared to the original alignment it also takes much less time (not counting 'Extracting Points' and 'Comparing Points'), which puzzles me a bit.