bumpy skin ...

[laurenz]

I am currently scanning a human hand and try to reproduce it with my 3D printer.

The 3d model in 3DF Zephyr looks quite good, but as soon as I export it (.obj) and load it into Autodesk Meshmixer, the surface of the palm gets totally bumpy.

For exporting I use the "Generate and export enhanced mesh" function, since I still use the free version. - I export to ".obj".

I get slightly better results if I set the "Edge filter" value to e.g. 0.5, but I do not understand where those bumps on the skin come from. In the model in Zephyr it is not visible.

[jupp2000]

[laurenz]

Thank you for the hint, how to see the triangles .... I am pretty new to Zephyr, so I did not know this.

Until now I just played with the parameter "Edge filter" in the "Mesh creation Settings Page". - Interesting the results for "0", "0.5" and "1":





The result for "0.5" is quite good, but I would like to also see the lines on the palm of the hand ...

As soon as I have time; I will try with more photos. - Although the current 37 photos are made with a good camera and a prime lens (OIympus PEN E-PL10 with 25mm/1.8, aperture set to 18).

[cam3d]

Hi laurenz

Just an additional note: If the subject moves at all, even slightly, this will translate to bumps on the surface as there's a certain level of inconsistency with the input data that Zephyr is attempting to work with.

For high end production results, it's highly recommended to scan a cast hand rather than a live one, but if this isn't an option then I'd recommend a dusting of talcum powder or similar on the hand to reduce reflections and add a bunch of little data-points (the grains of powder) for Zephyr to work with.

Feel free to share a dataset with us through a public file sharing service like google drive and we can give targeted feedback on image acquisition and processing settings for Zephyr.

[laurenz]

Ok .... so feel free to have a look into my project here: https://drive.google.com/open?id=16v...m&usp=drive_fs
(Please white for about 1 hour after my post for a complete upload of my set).

Remarks:
- All photos are masqueradet, so no background should be taken into calculations.
- All parameters have been default, except the following:
- Because not all pictures have been taken, I had to set "Keypoints sensitivity" to "Low" and "Matching type" to "Exact" in the "Project Wizard Settings Page"
- In the "Mesh creation Settings Page" I changed the "Reprojection area" to "5"
- "Edge filter" to "0" (default) gives a bad result, setting it to "0,5" or "1" gives much better models

Question: Since I did masquerading on all photos, so that no background should be visible, it should do no harm if the hand slightly moves during taking pictures, as long as the posture of the hand does not change (e.g. no movement of the thumb relative to the whole hand) .. ?

Here is the result of the current work with Edge filter set to 0,5 ...:

[jupp2000]

... respect that you could hold your hand so steadily, I can't do it.
Nevertheless, it is hardly possible to capture body parts with one camera without moving.
Even a little finger movement will ruin the result, unless you don't need it to be super precise.
In addition, there are too few images in my opinion (too little overlap between them, so some are not recognized.)

To start with photogrammetry you have chosen a difficult object :-)
To get a feel for the photogrammetry, I would start with a very simple, non-reflective object, e.g. a stone.
25 pictures from one side, 25 pictures from the other side.
That should work fine with the 50 picture limit.

To get high-res models from small objects i would recommend a turntable like this:
https://www.amazon.de/Hama-universel...s%2C181&sr=8-3


Kind regards
jupp2000

[jupp2000]

...maybe i got a bit more of details out of the model, but the shape at all will not get better here.
At least 2 images were out of focus.
For a little test how detailed you can reconstruct the skin, i would recommend to put the hand flat on a A4 Paper with spreaded fingers.
Than take 50 images just from the top side of the hand. It should work better.

[laurenz]

What parameters exactly did you change to get those fotos ?

Problem is, the hand has to be exactly that form, so putting on a sheet of paper with spread fingers is not an option ;-).

[jupp2000]

sharp textures will be only created in the very last step: "textured mesh generation"
The mesh contains only the normals...