Minimum Resolution Requirement per Camera

[Milkaholic]

Hi,

Is there a minimum megapixel requirement per camera for a successful 3D body scans?  Would 7.1MP be acceptable?

I read a comment on the following thread:  http://www.agisoft.ru/forum/index.php?topic=942.msg4638#msg4638.  "...that anything below 18MP really isn't great. You get OK results with 12MP but it's not ideal...Prime lenses are best for image quality. The key is sharp, focused, contrasted images. As much detail as possible, for good reconstruction."

Thanks,
Ryan

[admir]

We are using Canon EOS 1100 D (12MP) and Canon EOS 600D (18MP) for body scans.
We break scans into multi parts (head, lower body, upper body...) scaning and merge scans after.
12MP is pretty good for scans but you need proper light setup (key for good scan), good optic (as stock kits are not the greatest) and enough cameras.
However, we did tests with stock optic and good-ish studio flashes and results were good for our needs (realtime game development).

Admir

[Milkaholic]

Thanks Admir! 

If everything was calibrated the same between your 12MP and 18MP cameras, what is the difference?  Is it only how much you can enlarge the OBJ?  Or does camera resolution play a different role in photogrammetry?

[admir]

18mp is more (not much more) image resolution than 12mp and more details you can capture. We are using our custom built relay based trigger to be sure all cameras trigger in same time, as we experienced delays usign various usb and wireless shooters.

[Alexey Pasumansky]

Hello Ryan,

There should not be much difference between 12 and 18 MPix photos. More important, as it was already mentioned above, is to use good quality lens.

In general, lower resolution of images (assuming that camera positions remain the same) will result in worse accuracy of alignment and lower resolution of target mesh. Also low-resolution photos are more affected by noise.
I assume that comparable results with the low-res cameras can be achieved by more close shooting (and so more images to provide sufficient overlap), but haven't got sufficient experimental data to confirm that.

[Milkaholic]

Ah interesting!  Thanks Admir and Alexey.