DXF Import looses resolution

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ronH
Posts: 8
Joined: 01 Mar 2017, 03:02

DXF Import looses resolution

#1 Post by ronH » 23 Mar 2023, 09:04

I am working on an RFID antenna board. For that I am trying to generate a coil on the signal layers. I have done this a few times without any issues. But with my last board I run into a DXF Import issue. When I export the DXF file everything looks fine. When I start the import in diptrace I already see in the preview that the shape looks a little bit off. As if it generates to little points. After the import it is really obvious the shape is not retained and curved areas are now made straight lines. On one side the shapes even touch. The attached pictures will show what I mean.

I have tried to generate the DXF in several different version from R15 up to R2018. All have the same result. I hope somebody has a solution or workaround for this issue.

This is the export view (everything still ok)
Export_Full.jpg
Export_Full.jpg (112.63 KiB) Viewed 409 times
This is the import view ( top and bottom does not look right, left and right side are still ok)
Import_Full.jpg
Import_Full.jpg (91.88 KiB) Viewed 409 times
Detail of the import view (the side still looks ok)
Import_detail.jpg
Import_detail.jpg (78.86 KiB) Viewed 409 times
Than after the import (shape is not correct)
Imported_full.jpg
Imported_full.jpg (216.31 KiB) Viewed 409 times
Detailed view (shapes are even touching)
Imported_detail.jpg
Imported_detail.jpg (258.49 KiB) Viewed 409 times
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Ron

Tomg
Expert
Posts: 2028
Joined: 20 Jun 2015, 07:39

Re: DXF Import looses resolution

#2 Post by Tomg » 24 Mar 2023, 00:53

Try the following to see if things improve...

In your MCAD program, instead of drawing both sides of the "trace" (shape outline), draw a single line to represent the centerline of the trace. This should make it easier to draw the entire antenna. Use only straight lines and arcs (the fillet tool helps here). Take care to insure tangent constraints exist between connecting elements. For the example below the inner-most centerline (most difficult part) was drawn first...
mcad_2i.png
mcad_2i.png (52.12 KiB) Viewed 379 times
...then the offset tool was used to easily generate each successive outer centerline...
mcad1.png
mcad1.png (229.76 KiB) Viewed 399 times
Straight lines and arcs should import into the DipTrace PCB Layout editor as actual straight lines and arcs rather than a lot of seemingly-random polylines. After the DXF file has been imported into DipTrace, change the line width to fill out the antenna "trace"...
dti1.png
dti1.png (100.2 KiB) Viewed 399 times
By the way, I used the Autocad 2018 format to create the DXF file. When importing the DXF file into the PCB Layout editor things seem to behave themselves. When importing into the Pattern Editor, mysterious tiny alignment problems between drawing elements arise. It looks like something is not right with the Pattern Editor's DXF importer.

Hope this helps.
Tom

ronH
Posts: 8
Joined: 01 Mar 2017, 03:02

Re: DXF Import looses resolution

#3 Post by ronH » 31 Mar 2023, 06:35

Thanks to Tomg I got some new inspiration to try out some more methods.
To use only a single line in the DXF import simplifies a lot the design in the CAD application. It did not solve the issue with the shape being distorted. The shape was design as partial circles with a large radius. Probably that causes issues with the diptrace import. I redesigned the shape using splines which are converted to polylines at export. The import works now with sufficient resolution.

Thank you Tomg for the support.
CorrectShape.jpg
CorrectShape.jpg (93.04 KiB) Viewed 371 times
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Ron

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