DXF outputs in mils units; CAD software interprets mm

[Rob Maris]

Inventor and qcad intepret dxf units of KiCad exports as mm, while actually KiCad uses mils. As a consequence, enormous sizes are rendered. When dxf is primarily used for plain inspection, you'd not immediately see this in e.q. qcad, because the file is automatically zoomed to window size...

Apparently a unit definition is missing in export files.

[Lorenzo Marcantonio (l-marcantonio)]

On Tue, Dec 06, 2011 at 11:45:19PM -0000, Rob Maris wrote:
> Public bug reported:
>
> Inventor and qcad intepret dxf units of KiCad exports as mm, while
> actually KiCad uses mils. As a consequence, enormous sizes are rendered.
> When dxf is primarily used for plain inspection, you'd not immediately
> see this in e.q. qcad, because the file is automatically zoomed to
> window size...

Actually in decimils!

> Apparently a unit definition is missing in export files.

The real thing is me that don't know how to do UI programming :D

--
Lorenzo Marcantonio
Logos Srl

[Rob Maris (maris-rob-x)]

Am 07.12.2011, 08:27 Uhr, schrieb Lorenzo Marcantonio
<email address hidden>:

> On Tue, Dec 06, 2011 at 11:45:19PM -0000, Rob Maris wrote:
>> Public bug reported:
>>
>> Inventor and qcad intepret dxf units of KiCad exports as mm, while
>> actually KiCad uses mils. As a consequence, enormous sizes are rendered.
>> When dxf is primarily used for plain inspection, you'd not immediately
>> see this in e.q. qcad, because the file is automatically zoomed to
>> window size...
>
> Actually in decimils!
>
>> Apparently a unit definition is missing in export files.
>
> The real thing is me that don't know how to do UI programming :D
>

I'm sorry, but I can't judge whether this contribution is sarcasm or not.

[Lorenzo Marcantonio (l-marcantonio)]

On Wed, Dec 07, 2011 at 08:53:10AM -0000, Rob Maris wrote:
> > The real thing is me that don't know how to do UI programming :D
> >
>
> I'm sorry, but I can't judge whether this contribution is sarcasm or
> not.

Sorry, didn't mean to upset you... the story was something like that:
I added the DXF exporter (it's a plotter, actually!) during a period
when the plot dialogs where overhauled. So it just stuck like that in
its default state.

IIRC there already are the scaling factor for a customizable export,
they just are not user visible (since, as I said, I'm no a wx GUI
expert).

I'd put it as a wishlist until somebody wants to touch the plot dialog.

--
Lorenzo Marcantonio
Logos Srl

[Rob Maris (maris-rob-x)]

> Sorry, didn't mean to upset you... the story was something like that:
> I added the DXF exporter (it's a plotter, actually!) during a period
> when the plot dialogs where overhauled. So it just stuck like that in
> its default state.

Lorenzo, thanks for clarifying things.

> IIRC there already are the scaling factor for a customizable export,
> they just are not user visible (since, as I said, I'm no a wx GUI
> expert).

Well, I don't think that an extension to the GUI is necessary. I'd suggest
you to a simple patch in your exporter that defines the unit of all
metrics at the start of a dxf file. At least I found some variables that
can be used to specify angle units, metrics units etc. I'd believe that a
qcad or comparable 2D programs would interpret correctly when the units
are specified. I treat it as a second step to output all stuff in mm,
perhaps when anybody's going to add a bit rounding to all mm output of
KiCad to max. three digits instead of four.

-Rob

[Novak Tamas (novak-7)]

It's the opposite actually: KiCad exports mm's, and MCAD (Creo 2.0 for me) loads the pure numbers as inches. KiCad's 70mm PCB looks 1778mm in Creo.
DXF file contains a header, where any number of system variables are held. If KiCad DXF exporter writes something into the file (like UNIT=mm), a lot of different MCAD's should be checked if they receive such a parameter (and from which codewords, which format...)
In Creo it's easy to change the units "on the fly" without converting values (70 inches will be changed into 70 mm's)

[Launchpad Janitor (janitor)]

[Expired for KiCad because there has been no activity for 60 days.]