3DF Zephyr – the complete photogrammetry software suite – from photos to 3D models › Forums › [ English ] 3DF Zephyr › Questions regarding measurement and scaling
10/01/2017 at 23:47 #7342
After reading through the documentation and the tutorial on control points and distances, I am hoping to clarify my understanding of how to precisely scale a human body mesh for export as .obj or .ply.
• Regarding accurate scaling of a final human body mesh:
o At what point in the project process should control points be created from photos?
Is it possible to add them to a new project after adding pictures but before running the sparse point cloud?
Or can they be added even after the mesh is already created and still effectively scale the existing mesh?
o Is it correct to assume that given excellent camera calibration, and correct unit of measurement setting, that the default numbers displayed for distances will match reality and result in a perfect scaling of the model?
o How do I know the scale has been applied?
Is it always applied once the Scale model with Control Points or distances dialog has been filled out?
What, if anything cancels the scaling, and reverts the scene and model back to its default size and shape
o I am hoping to clarify my understanding of the meaning of the constraint versus control check boxes in the “scale model with…” dialog boxes.
What is the difference between “Control” and “Constraint”
What is the consequence of checking either one or the other or both?
o when in the 5 step process, should scaling according to control distances be applied to achieve the most accurate scaling of a full body mesh?
• What is the difference between the measure volume button and the measure volume after projection button on the measurement panel?
• When I click the measure volume button and assign a place to save the computation mesh, the file created is empty. On windows 10 I can see it in recent files but I cannot see it in the directory where I chose to save it. Is there something I am missing?11/01/2017 at 15:30 #7343
Hi Modeler 17,
I am going to reply you following your order:
– Control points can be placed at any moment of 3D reconstrucion, even after the first phase of cameras orientation for instance;
– At now it is not possible;
– Yes, they can be created after creating a mesh;
– Scale accuracy depends on user’s precision while placing control points;
– You will notice that the value of the control distance you exploited to scale the model is changed;
– What do you mean by that question? Could you provide me with further details?
– In that case, users are requested to perform scaling procedure again;
– After you have placed your points in Zephyr, you can choose which points must be the constraints, namely the points you are confident (of their accuracy) the most, and which points will be taken into account as simple references. Let’s think about an aerial survey where you have both coordinates taken by the GPS system on drone and some coordinates on the ground taken with a total station. The first group will be the points taken on ground with the total station since their accuracy is definitely higher than GPS coordinates taken by the GPS system on drone representing the second group.
– Yes, it must be applied in order to reach a fine result;
– They simply are two different methods to calculate and visualize meshes volume. As for the first one all holes are automatically filled and later shown with a red color;
– We are checking the issue and I will keep you up to date as soon as it will be solved.
Giacomo11/01/2017 at 20:17 #7344
Thank you for all of these answers to my questions.
Regarding the question you wanted more information on:
What I am trying to confirm is, once I scale the model, whether there is a quick way to disable/re-enable scaling.
I assume scaling would be disabled if I delete all control distances and control points. But I want to know if control distances and control points persist any where without exporting them before deleting them.
Thank you again.11/01/2017 at 23:23 #7345
thank you for your explanation.
There is not a specific button to disable and re-enable scaling. Nevertheless you can select a previous action inside the History panel located on the left side of the main interface of Zephyr. You’re allowed to do that as many times as you want.
If you only delete control points /control distances your 3D model will keep the last scale value you set.
Lastly, we have fixed the bug concerning volume calculation. Zephyr 3.1 will be released within the end of January and I would be glad to send you a trial key in order to test out its improvements. Feel free to contact me at firstname.lastname@example.org and I will keep you up to date.
Giacomo12/01/2017 at 01:38 #7346
Thank you, Giacomo.
The history panel sounds like it will allow me to do what I need to do regarding effectively disabling and re-enabling scaling.
I am glad to know about the upcoming fix for volume calculation save bug. The fix is something I will indeed want to test once 3.1 is available.
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