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Extracting feature information from 2D CAD engineering drawings

asked 2020-07-02 15:17:28 -0600

robert_m_muench gravatar image

How would one approach the problem to extract information like the biggest diameter, smallest diameter, number of wholes, the diameter of wholes, widths, length, etc. from engineering drawing?

I'm interested in the general approach to such a problem. Which algorithms, etc. are best suited?

Problems I see:

  • Different graphical symbols used to encode things like welding areas
  • Text is separated from an area where it belongs to but attached via arrows
  • rotated text
  • specifying which information to extract, not everything is needed

The output would be a table where the features are in columns and the different drawings are per line.

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answered 2020-07-02 15:51:26 -0600

kpachinger gravatar image

Considering...

  1. pace of plan revisions
  2. multiple representations of the same details
  3. users' local settings [i.e. delimiter, regional symbols, color code]
  4. variations in output raster

It would be rational to have them export a CSV file(s). Rolling your own OCR would be continuous cache miss.

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The use-case I have is, that thousands of such drawings exist, mostly as PDF, some even only as raster image and there is no chance to access any original files.

  1. is no problem, because I focus on legacy data. For new stuff, machine-readable data is simpler to get.

  2. 2.-4. are all valid points and need to be handled.

robert_m_muench gravatar imagerobert_m_muench ( 2020-07-03 02:07:43 -0600 )edit
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Respectfully (not to deter you)... with only thousands and so many criteria, would you not use a temp/intern? Data would need validation regardless.

kpachinger gravatar imagekpachinger ( 2020-07-03 03:46:42 -0600 )edit

Yes, that's what we currently propose. But companies love “let's automate this" and there can be around 500.000 drawings. If all these need to be analyzed (automatically or manually) is a different story.

robert_m_muench gravatar imagerobert_m_muench ( 2020-07-20 06:09:20 -0600 )edit

Make a portal. List the documents with status (new,pending,approval,error,done). Have a sidebar with sets of visual reference symbols/tools. Develop software as you make progress for real feedback and results. Farm the annotation/review out. Maybe there's a onionskin with original, OpenCV detection, and a cross-reference to editable database fields. Get production startup semi-automatic, always progress...

Also, does this service exist at $0.01/document, or should you protect any future copyright/development? For example, upsample documents, is that in scope?

kpachinger gravatar imagekpachinger ( 2020-07-26 06:11:33 -0600 )edit

Sorry for being that late...

We had the portal idea too. Would be a desktop tool where one captures some data directly...

Don't understand your last questions.

The idea is that companies can use this tool in-house and build-up a shared-service or use a shared-service provides who use the tool.

robert_m_muench gravatar imagerobert_m_muench ( 2020-08-29 07:05:10 -0600 )edit

Yes, I was curious if your intent was SaaS. Advancing from a question of high-level feature requirements to implementation... i.e. a Java developer with a background in drafting.

kpachinger gravatar imagekpachinger ( 2020-08-29 18:47:01 -0600 )edit
  • whitelist symbol library / dictionary
  • blacklist patterns, i.e. hatching
  • internationalization
  • preflight routine i.e. upscale img or convert pdf
  • interactive annotation / hints for interpreter to refine output
  • multiple view / detail consolidation
  • text(s) recognition
  • unit conversion
kpachinger gravatar imagekpachinger ( 2020-08-29 19:41:52 -0600 )edit

That's a good rough summary :-)

Are you aware of any OpenCV examples, that analyze such CAD drawings?

I'm not sure yet, how much AI training approach is needed, or if such information can be handled with an algorithmic approach or if a mixture is a way to go. And for an AI approach, how many training data will be necessary. Any experience?

robert_m_muench gravatar imagerobert_m_muench ( 2020-09-09 02:23:53 -0600 )edit

There are many text recognition examples, classifiers, etc. in multiple languages. Maybe thousands of labelled training data to start? I am only learning myself, but I have been in startups... "window-shopping" solutions. The pace of progress has people turning to cloud services and certified specialists, but you still need the language to specify. Granted, there is fluidity of expectation and budget, staff. So maybe it's a Mechanical Turk at first and then it evolves. A viable POC.

Do any modern CAD programs offer or project this service? Adobe? It seems within scope.

kpachinger gravatar imagekpachinger ( 2020-09-09 06:20:10 -0600 )edit

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Asked: 2020-07-02 15:17:28 -0600

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Last updated: Jul 02 '20