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Author Topic: Exported obj not proportional  (Read 985 times)

JayEll

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Exported obj not proportional
« on: September 30, 2020, 08:52:18 PM »
Hello,
i created a perfect model of a cello plate (Standard Version), let`s say, looks perfect. When i import the obj in Blender or Cinema and scale one dimension to it`s
original width, the length of the plate is not proportional. The original width of the plate is 45.5cm and the length is 75.2cm.
When i scale it to width 45.5cm the length is 73.3cm only. I sprayed the white/yellowish plate with mordant spots and the photos aligned perfectly in one chunk.
Is there something necessary i forgot. Should i place targets directly on the plate with known dimensions? Never did because i mostly do food photogrammetry
and never checked the exact dimensions (proportions). How can i make sure that my model is 1:1 to the original. Scale bars? If yes, how to.

Attached a screenshot of the created model.

Thank you all

JMR

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Re: Exported obj not proportional
« Reply #1 on: October 01, 2020, 01:43:01 AM »
can you post a creencapture of the model view with photos turned ON ? I'd like to see cameras distribution and relative orientation.
Metashape Standard shoul not be considered a metrology tool. Even if it uses same algorithms as Pro, the lack of instruments for creating geometric constraints like scale bars and control points, leads or can lead to deformed models.
These constraints play a fundamental role not only for determining the external orientation of the model (scale, rotations and position) but also in the relative and interior orientation, and therefore in the shape and proportion.
Metashape Standard can deliver accurate models, but the lack of control makes it umpredictable. Accuracy will be conditioned by too many factors and the actual shape of the object is one of them.

JayEll

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Re: Exported obj not proportional
« Reply #2 on: October 01, 2020, 08:45:18 AM »
Thank you so much for your detailed reply. Please find attached a screenshot, cameras turned on.
I need to solve that problem, do you have any hints?

Best wishes

JMR

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Re: Exported obj not proportional
« Reply #3 on: October 01, 2020, 10:05:22 PM »
I can't say, what could be the source of your problem. Actually your networks looks pretfy robust, and the only thing I can say it could serve to improve it is to mix some ring with camera rotated  in portrait (as opposed to landscape).
Also I would ask what camera/lens combo and what focus setting were used.
Regards

JayEll

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Re: Exported obj not proportional
« Reply #4 on: October 02, 2020, 10:54:15 AM »
I will give a try with some additional photos in portrait format. All Images, Sony A7R, Sony 24-70/2.8 @50mm, focus manually.
Shoot directly in Capture One.
Thank you!