Scan and photogrammetry won't merge correctly

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Raphaël 1

• July 21, 2020 15:26

HI, 

I'm trying to create a 3d model of a simple room. I'm working with two components. One is a scan done with a BLK360, the other is a dataset of 900 photos taken with an A7RIII.

When I try to align them together into a single component it doesn't work. I get two new components : "Component 0 (1)" and "Component 1". 

When I have try to place control points, both components merge but the alignement isn't perfect. The ground and the walls are worse than in each individual component. 

Is there something I am missing ?

Thank you  !

Here are both components :

The scan -

The photogrammetry -

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  Erik Kubiňan CR

  • July 22, 2020 09:20

  When merging the components with control points, place them across all of the walls and some on top and bottom if possible. When the CPs are correctly distributed and not just in one place or only in center, they will most likely do the job correctly.

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  Raphaël 1

  • July 22, 2020 16:19

  Hi Erik,

  Thanks for the advice. I placed 4 CPs at the corners of the room. Two at the top of the room and two at the bottom. 

  

  

  Both components merged together but it's not perfect. I'm launching a reconstruction tonight to see how well it worked.

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  Erik Kubiňan CR

  • July 23, 2020 06:04

  Well if it is not perfect yet, I'd suggest to place more this way. If this would not help then another thing is causing the issue. 
  Opened door on one set closed on another 
  Drastic change of light between the two sets 
  Ultra wide angle lens with heavy distortion could have been used

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  Raphaël 1

  • July 23, 2020 10:12

  Hi Erik,

  Here is what I'm talking about - I did a normal detail reconstruction and the ground is supposed to be flat but it isn't. 

  

  Is this due to a misalignment ?

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  Erik Kubiňan CR

  • July 23, 2020 10:47

  Definitely looks like that Raphael. Try the suggested above and maybe add more control points directly on the ground where this effect occurs, there is an obvious height shift there.

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  Raphaël 1

  • July 24, 2020 09:19

  Hi Erik

  It worked better when I placed several control points near the height shifts.

  I have another question for you, near he places I placed my laser I get this effect. How can I fix it.

  Here are two pictures to show this effect, both laser were placed on the edge of the reconstruction region.

  

  Thanks for the help !

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  Erik Kubiňan CR

  • July 24, 2020 16:56

  Not sure what exactly do you mean as the issue, but as long as it is the circle, this always happens with terrestrial scanners. They can't see under themselves so this is what happens then on their position. You can override that by photos I think if you put it away afterwards.

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