Ask Lemmy

27338 readers

3828 users here now

A Fediverse community for open-ended, thought provoking questions

Rules: (interactive)

1) Be nice and; have fun

Doxxing, trolling, sealioning, racism, and toxicity are not welcomed in AskLemmy. Remember what your mother said: if you can't say something nice, don't say anything at all. In addition, the site-wide Lemmy.world terms of service also apply here. Please familiarize yourself with them

2) All posts must end with a '?'

This is sort of like Jeopardy. Please phrase all post titles in the form of a proper question ending with ?

3) No spam

Please do not flood the community with nonsense. Actual suspected spammers will be banned on site. No astroturfing.

4) NSFW is okay, within reason

Just remember to tag posts with either a content warning or a [NSFW] tag. Overtly sexual posts are not allowed, please direct them to either [email protected] or [email protected]. NSFW comments should be restricted to posts tagged [NSFW].

5) This is not a support community.

It is not a place for 'how do I?', type questions. If you have any questions regarding the site itself or would like to report a community, please direct them to Lemmy.world Support or email [email protected]. For other questions check our partnered communities list, or use the search function.

6) No US Politics.

Please don't post about current US Politics. If you need to do this, try [email protected] or [email protected]

Reminder: The terms of service apply here too.

Partnered Communities:

Logo design credit goes to: tubbadu

founded 2 years ago

MODERATORS

What cheap setup or technique works for truly flat photos for use in CAD? (lemmy.world)

submitted 3 days ago by j4k3 to c/asklemmy

21 comments fedilink hide all child comments

I've managed to do reverse engineering of circuit boards using GIMP and rough alignment of layers using images like the one pictured. I want to use images to reverse engineer parts in CAD, but the minor lens distortion of a camera on a phone at ~20cm high on top of a stack of objects to keep it eyeballed flat is not enough. The result is off in multiple planes. There are minor errors in my curves in the transparent CAD part pictured, but the hole pattern is correct. The picture has been calibrated to 20mm against the ruler. Any suggestions on how to make this usable for replicating the ellipse that crosses the holes ±0.05mm?

you are viewing a single comment's thread
view the rest of the comments

[–] [email protected] 11 points 2 days ago (2 children)

As others have said, using a flat bed scanner will save some work. If you need to photograph it though:

Use paper with grid lines as background (not sure the name, used to use it in maths at school). This will give you not just an index for scale but also for 'squareness'.
Position camera perpendicular to subject
Use a telephoto or zoom lens from a distance rather than wide angle from close up to minimise lens distortion.
Import image into GIMP or photoshop and use rulers, guides and transform tools to scale the image correctly and make it perfectly square.
Matching the colour perfectly is more complicated and I won't go into that here.

Let me know if you need any more tips. I photograph a lot of artwork and documents.

[–] cellardoor 5 points 2 days ago

Graph paper is the squares paper, I believe :)

load more comments (1 replies)