Newbie help with retaining size of image on import

[Greig]

Hi All,

I'm a complete novice and new to Inkscape and in need of some advice .  A friend and I are embarking on a project and we require to be able to take a .stl file of a 3d item and have it converted and available to use in Inkscape to that items exact size.  Its a custom part so we can't have any change in the size. 

So far I have taken the .stl file and imported to Blender where I've then rendered it down to a 2d .svg file, but when I open that svg file in Inkscape the item is as much as quadruple  the height and twice the width.  Being a complete CAD greenhorn I don't know if that change took place in blender or if its a scaling thing in Inkscape.

Any help would be gratefully received on how to maintain the items true size so that it can be sent for laser cutting.

Best

Greig

[brynn]

Welcome to the forum!

I'm not sure if I can completely answer your question or solve the problem.  But I can take a couple of whacks at it.

One problem might be different native resolutions between Blender and Inkscape.  Although having said that, I'm not sure what Inkscape's native resolution is.  I think it might be 96 dpi, although I should say that I get terribly confused by the terms "resolution" and "dpi".  So I might not have that right. 

However, if you're talking about vector paths, resolution is irrelevant.  When you do whatever you did with the image in Blender, to make it an SVG file, is it still vector paths?  Or did that change it to a raster image?

In any case, I wouldn't think different resolutions should result in that much of a difference in size.  The other possibility that I can think of is that you might have your Scale set improperly in Inkscape.  Did you change your Display Units in Document Properties > Page tab, at the top of the page?  If you did not change it, then the Scale setting is not the problem.  If you did change it, then Scale might be part of the problem.

Did you say that the image did not even keep its proper proportions?  You said it got 4 times taller and twice wider.  As far as I know, that could happen if you changed the scale on purpose, and you changed both X and Y values.  Although I'm not sure how to un-gray-out the Y value for the scale setting.  Or possibly if you changed the Viewbox (just below the Scale setting in Document Properties). 

Did you change any of those?

By the way, Inkscape is not a CAD program.  I don't think Blender is either.  (Even though CAD means, I think, computer aided design, CAD refers to specific type of graphics software - drafting software, I think.  So not all computer graphics programs are actually CAD programs.)

Last question.  After you changed it from 3d to 2d in Blender, did you confirm that it still was the right proportions?  Or could the problem have started in Blender?

[Lazur]

Previously I had precision issues the other way around -importing an svg from inkscape to blender had a tiny bit of proportional error in height/width.
Thus instead exporting to dxf from a cad program, converting the dxf to an svg and using that as a base didn't work out for me.
Instead, now saving straight to an obj file and pulling that into blender.

Would try to do the same in reverse as an option.
Export to an obj file, then use the render 3Dpolyhedron extension for "importing".
Had used this approach on this project although I eithe didn't know of a native svg export in blender or it wasn't even available at the time.

[Greig]

Hi all, many thanks for the replies.  Excuse the generic reply too please but I’m on my phone and can’t see where to reply to individuals.  You’re insight is invaluable to me so thanks for that.  I’ll take your suggestions and points on and look into things further based on your thoughts.  For now I’ve just made sure that when I import to Inkscape I bash back in the original file size from the .stl so that it reverts as close to the true size as possible.  I have another issue if I may pick your brains on this one?!  I have a logo in .svg format that is black.  I’ve changed the stroke and fill to blue so when it’s exported to laser software it recognises blue as ‘engrave’. But when it’s imported it’s changed back to black.  Is there something I’m doing wrong?  I suspect it could be the laser software “k40 whisperer” that made the change but any help appreciated.  Thanks

[brynn]

In this type of forum, it's better to reply to everyone, rather than individuals, especially when answering messages to the question you posted.  However, if you need to communicate with someone personally, you can use Personal Messaging.  Look for the Messages tab, in the main menu.

When the path color was changed from blue to black, where were you importing the image?  Before you imported it, did you save it to a different format? 

If the laser cutter requires for paths to be a certain color, to decide which type of cutting to perform, it doesn't make sense for the cutter software to change the color.

I don't think all laser cutters require different colors for different types of cutting, although I'm not positive.  Maybe a good idea to refer to the documentation for that machine, to be sure?