Tired of PhotoScan, I just want it to Work: 2/N

Since the last Blog post, I finished going around the object and selecting enough cameras to get a decent set of dense point cloud going.  I did this in four chunks; I was trying to quarter the model with each chunk:

9 cameras
1553 points
17 cameras
3260 points
10 cameras
2332 points
11 cameras
2575 points

Lets Align Some Chunks, Shall We?

Align Chunks, Camera Based, 1 Camera overlap

Nothing.  It needs more cameras?  I could see it being in 3 dimensions, it would need 3 cameras minimum.  I’ll come back to this with more cameras in overlap.

Align Chunks, Point Based


Not Quite.   And as far as I can tell, there are no manual align controls anywhere (in the non-professional version).

I could take this out to Meshlab and try to align it there, however, I won’t later be able to map a texture; I have to solve this in PhotoScan. 

Add More Cameras, Align Chunks, Camera Based, 3 Camera Overlap

While I’m at it, I also add in a few more cameras in some of the gaps that I see.  And this is what I get:


Queue Darth Vader Imperial March

I can tell it got the cameras correct.   However, my fear is realized:  I think as I walked around the subject, he moved slightly.  Or, my distance from the subject was not constant, so I ran into some lens calibration issues, and thus the resultant object was not mapped at the correct size.    Either way, what we have now is a FrankenDan.


I cannot resist.  Going all the way through to a model and texturing this beauty – and learning how to do an animation in blender at the same time —

Franken Dan Murphy

Attempting a single chunk with the same 55 cameras


What is happening is either a) the model moved, or b) I changed distance from the model (and the camera alignment is wonky), and it just cannot get the math to work.  FrankenDan is actually a better representation of the reality that was captured. 

So.. I don’t think there is a solution here, with a GoPro Hero3 walking around a subject.   There are several directions I could go, though:

  • Start from the back of the subject, so that the seam would be in the back.
  • Put markers on the person’s back (so that there is something to “fix” on), or give them a “garland” of some sort.
  • Use the 120fps to capture the model quicker; but I need to find a reliable way to spin the camera around the subject and hopefully not invoke motion blur.  (Hula Hoop Mount?)
  • Use a better camera (not a GoPro); perhaps a DSLR; with a ring laid out for distance from the subject (see teaser solution below)
  • Use multiple cameras! (so many people have had success with this – and they don’t have to be good cameras either)

Teaser Solution:  DSLR

In comparison, here is me, taken via a DSLR camera with a 50mm fixed (prime) lens.  Its not quite printable, as the (shiny? homogeneous?) back of my head failed to capture.   There’s definitely something to be said for not using a GoPro.


Author: sunnywiz


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