[Patentpractice] FreeCAD and Inkscape for patent drawings, hatching versus shading, and OS questions

[Timothy Snowden]

I've used all three. They work, and are great. I still use Inkscape on 
at least every other application (I don't use Visio, but I do use 
WithEdge for drafting -- hence my less reliance on flowcharting). I use 
FreeCAD semi-regularly to open a STP file and generate SVGs to take to 
Inkscape and modify. DrawIO is also a good project for flowcharts (free, 
but not fully open source) because Inkscape is not the greatest / most 
efficient with flowcharts. yEd is also a good graph editor (again, free 
but not open source) and runs on Ubuntu last time I looked.

1. Inkscape - I created a template with different common drawings I 
commonly use. If I'm preparing a complete drawing set in Inkscape, I 
really like Inkscape's ability to look at all the pages like a 'canvas' 
instead of one at a time. I also use snapping heavily. So I guess that 
answers your questions -- I build out the drawing pages directly on 
Inkscape. I've thought that Inkscape's extensability would open the door 
to a really nice patent drawing specific plugin for automatic numbering, 
generating a reference list, etc. ... but never had time to pursue that.

2 & 3. I've run both on Ubuntu. For a few years I ran only on Ubuntu for 
all patent drafting. FreeCAD & Inkscape both run well on Ubuntu -- 
possibly better than on Windows. No particular advice -- they pretty 
much install natively. If you plan to modify them you might want to 
avoid snaps, as those aren't as friendly to modification.

4. Not FOSS, but I use PDFX-Change to rasterize everything to B&W anyway 
- I forget the exact algorithm but it does a pretty good job of getting 
shading as close visually as you're going to get in B&W only. Probably 
my primary pain point on Ubuntu is the lack of really good PDF software. 
Good CAD software used to be the other lack (VariCAD was your primary 
paid option), but FreeCAD is plenty capable now.

5. For shading, I typically try to use a cross-hatching pattern fill in 
Inkscape and avoid 'shading' per se. However, if you're coming from 
FreeCAD, you can cross-hatch a cross-section (by default), and change 
green to B&W, and it comes out pretty good.

6. Not sure -- I would imagine so, but I'm not clear exactly what you're 
doing in shading, so there may be several tools that could do it.

7. Theoretically, yes.

8. Well, no, since we can't see the source and AFAIK PatentCenter 
doesn't publicly adhere to a given color standard, I guess we can't know 
that PatentCenter will reliably properly interpret those, but that would 
equally affect all other files too, since that's how everybody else is 
defining the colors too. So ... I think that it's safe to rely on from a 
practical point of view.

Hope that helps.

On 10/22/2025 8:30 AM, Rick Neifeld via Patentpractice wrote:
> *Background and Questions:*
> Being able to prepare complicated patent drawings has been on my 
> professional bucket list for a couple decades. To do so with purely 
> open source software is kinda on that list.
>
> I can now design 3D models, generate 2D engineering drawings 
> therefrom, and export the drawings to SVG, from FreeCAD. And I can use 
> Inkscape to import the SVG files and readily mark them up with sheet 
> numbers, Figure numbers, reference characters, curved and 
> straight lead lines, arrows, and feature numbers, and then export them 
> from Inkscape to pdf (or to a bit mapped image format suitable for 
> including in a strict DOCX file).  And both FreeCAD and Inkscape are 
> free and open source.
>
> 1. Has anyone else gone down this path and have any observations, dos 
> and don'ts, or the like?  Did you use all ten default (or multiple) 
> views in a page or stick to one view? Why or why not?
>
> *Ubuntu Compatibility*
> I am currently using FreeCAD and Inkscape on Windows 10.  Upon review 
> of Windows 11, it seems to me a bridge too far.  Windows 11 locks the 
> user in to Windows and MS products for all eternity. The combination 
> of a TPM 2.0 chip required by Windows 11, mandatory secure boot, and 
> automatic turnon of bitlocker on boot, tied to the users microsoft ID, 
> does that.  Ubuntu, FreeCAD, and Inkscape are all free an open 
> source.  And I have enough technical oomph to load and use ubuntu on 
> some computers. So I plan to do that, keeping my existing Windows 
> boxes, but moving to all free and open source.
>
> 2.  Has anyone run FreeCAD on Ubuntu?  Got any sage or stupid advice?  
> Any difference from running on Windows?
> 3.   Has anyone run Inkscape on Ubuntu?  Got any sage or stupid 
> advice?  Any difference from running on Windows?
>
>
> *Hatching versus shading*
> Hatching, what the patent rules identify as oblique lines to identify 
> cross-sections.
> Shading, what the patent rules identify has usable to identify curved 
> surfaces and, in perspective view, flat surfaces
>
> 4. My issue here is the PTO conversion of image data to bitonal, at 
> least for pdf images.  First, I am guessing that bit mapped objects in 
> "DOCX" files are likewise converted to bitonal.  Does anyone know if 
> that is the case?
>
> 5. Assuming PatentCenter converts to bitonal an uploaded grayscale pdf 
> image file, how does it handle "shading."  Shading seems to be 
> ambiguous because it defines what we see and not the data format. For 
> example, I could make something look shaded rendaring a a bitonal 
> image file in which every third pixel was black, the rest white.  But 
> that is not generally how its done, right?
>
> 6. Is there some method of defining in Inkscape (or some other svg 
> file editor) shading in bitonal data format?
> 7. Can I define the line spacing and dimension small enough in 
> Inkscape so that the result appears to be shading instead of 
> individual lines?  If so, what settings?
> 8. FreeCAD and Inkscape allow for RGB or RGBa settings that are 
> equivalent to white, and black. For example, 255,255,255 and 0,0,0.  
> Do we know that PatentCenter will interpret those as the proper 
> bitonal values, aka white and black?
>
>
>
>
> Best regards
> Rick Neifeld, J.D., Ph.D.
> Neifeld IP Law PLLC
> 9112 Shearman Street, Fairfax VA 22032
> Mobile: 7034470727
> Email: RichardNeifeld at gmail.com;
>
>
>
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