Curved scan

[GrahamF]

Hi,

I'm working on producing a model of a small coin, and I've been having issues with the scan coming out with a curve. The photos seem to align correctly, and produce a pretty decent looking dense cloud. The coin was placed on top of a scale bar, which is completely flat, but there is a noticeable and seemingly fairly regular curve in the resulting model. Hopefully the attached image makes it clear what I mean. The photos were taken with a Canon 5d mkIII, using a 100mm macro lens on f22 (to give sufficient depth of field). I suspect the problem might be caused by lens distortion. If anyone can confirm that and suggest any ways to deal with the problem I'd really appreciate it.

Thanks

[outsider]

I had this problem as well in the past.
Run the camera calibration (take images of the checker board image on the screen with the camera as instructed in the user manual) and generate a lens calibration model.
The apply that lens calibration data to the chunk you're processing.

It will fix the curved model you have.

[GrahamF]

Thanks outsider, that's really helpful. I'll give that a go.