True Arcs & Circles in PDF's

David Waight

Dear Forum,

I already have this as a Support question, but thought I would throw this open to the forum while I am waiting to confirm if I am doing something wrong.

I trialled Bricscad V13 when it first came out last year and was delighted to find that exporting to PDF was a true export as Arcs and Circles remained as they should be. I didn't purchase Bricscad at the time as I was waiting for the inclusion of user defined variables, which I was delighted to find in the latest upgrade, so I trialled Bricscad again.
This time around I have discovered that unless I am doing something completely wrong, the export of PDF's no longer creates true Arcs and Circles, but recreates them as multiple short lines. Could someone else with the latest version please tell me if I am doing something wrong or is this a regression?

I have also noticed that when exporting PDF's, a solid hatch is created as a PNG raster file as opposed to a vector fill. This can result in very large file sizes if there is a lot of solid hatches and produces strange results when opened in Graphics software.

There is every possibility that this time around I am doing something completely wrong during the PDF creation process, so thought I would see if anybody else has noticed any of the above.

I am exporting to PDF and not Printing to PDF and have tried altering the VIEWRES and all this does is give me an Arc/Circle approximation with more smaller lines in it.

Many thanks in advance,

David Waight

Roy Klein Gebbinck

I don't think you are doing something wrong.
If you check the Release Notes you can find two references to this issue:

Version 13.2.4:
Improvements:
PRECISION: the VIEWRES system variable now also affects the calculation of arc approximation precision (used for rendering and PDF export).

Version 13.1.5:
Fixes:
SR34499, SR35307 - PDF EXPORT: when arc segments of a polyline were exported to PDF, they were represented as a chain of lines instead of arcs.

So it seems that what you are seeing was not by design in V13.1.15, but is so in V13.2.4.
Although I am surprised that VIEWRES is used for this purpose. AFAIK it should only influence the display on the screen.

Terry Dotson

The PDF file format does not have a CIRCLE or ARC object.  The closest thing is PATH(s) which can be made with 4-point Bezier Curves to simulate arcs/circles.  Also keep is mind that PDF is simply a popular plot file format.

Knut Hohenberg

Fully working pdf output is one of the features I am eagerly awaiting on linux. I thought it would already be there on windows, but this post really makes me wonder.
On the last linux release (13.1.19) the situation is as follows:
- if you print into a pdf file (via cups), circles, arcs and ellipses will be written as polygons, solid hatches will be turned into filled polygons , and text will be exploded to curves.
- if you export as pdf, circles, arcs and ellipses will be written as (bezier) paths, while solid hatches will be written as meshed for screen display (resulting in many filled triangles).
(ttf) Text has to be turned into geometry in the export settings, or will be omitted completely.

So you currently have the choice between two not really satisfying options.

My expectation would be for curved geometry to translate into bezier paths, solid fills to filled paths, and annotations to searchable text.

David Waight

Thanks for all the replies, but I am still a little bit confused.

There has obviously been a regressive change to the creation of curved entities in PDF's (see attachments which are from 13.1.7 Drawing1 and 13.2.4 Drawing3).

It is also my understanding that PDF isn't just a plot format as mentioned by Terry (I appreciate what you are saying about paths) as it is apparently the basis for Illustrator's file format ("Adobe Illustrator, as with other Adobe programs, is built on core PDF technology. In fact, the native Adobe Illustrator file format is PDF, and as such it is one of the best applications supporting direct export to PDF").

This can be seen if you (In Windows) Open With..., the attached Illustrator file in Acrobat Reader or any of the free pdf readers, you will notice it will open no problem.

The only reason I have these concerns is I need to present my CAD files to Graphic Designers to apply Artwork to and it can lead to all sorts of problems if I am supplying a PDF file to somebody that creates artwork that looks like a polygon, which is really a circle and when the tooling is made to cut the shape out, the artwork will have been done to short straight vectors and the tool will be cutting a circle so the printed Artwork wouldn't match the shape of the tool.

I can fully appreciate the convenience of printing to PDF if the file is only for reference, but if for example someone is using a CAD file as part of a Technical Manual would you not want to supply the PDF so it had arcs, beziers or paths as opposed to jagged straight lines?

Apologies for going on a bit, but I am just trying to understand how the PDF's are constructed from Bricscad.

I will leave the PNG hatch question for another time.

Regards,

David Waight

Drawing3.pdfIllustrator File.aiDrawing1.pdf