kicad-developers team mailing list archive

[Seth Hillbrand <seth@xxxxxxxxxxxxx>]

The document I linked is the HTML version of the ISO/IEC standard as
published by the Web3D consortium (previously known as the VRML
consortium).  There is no textual difference between the PDF of the ISO
document and the webpage.

If Wings3D doesn't use this, then it makes sense that we may have
originally chosen the unit used in Wings.  But that doesn't mean that we
need to continue this practice.

-Seth

On Tue, Sep 29, 2020 at 4:08 PM Cirilo Bernardo <cirilo.bernardo@xxxxxxxxx>
wrote:

> Hi Seth,
>   What you have on the w3 site is essentially an interpretation by the
> author of that page;
> the spec referred to reads differently. At any rate, that doesn't change
> the fact that existing
> software for creating VRML (including Wings3D that many KiCad users used
> long ago)
> don't use a unit of 1m - and it all really comes back to the spec being
> poorly worded and
> various implementers interpreting it differently. If it sounds like I'm
> being pedantic it's
> because I've implemented too many standards specs over the years and
> suffered
> poor implementations even on points where I thought the language was clear.
>
>
> On Wed, Sep 30, 2020 at 8:58 AM Seth Hillbrand <seth@xxxxxxxxxxxxx> wrote:
>
>> I don't follow your statement.  The standard says "ISO/IEC 14772 defines
>> the unit of measure of the world coordinate system to be metres."  There is
>> no ambiguity here, so I would feel comfortable with saying that KiCad also
>> defines the VRML standard unit to be meters (metres).
>>
>> As to the file savings, this is easily addressed by defining a single,
>> new coordinate system in inches or microns that scales the global system.
>> All units in the file are then in scaled coordinates.
>>
>> -Seth
>>
>> On Tue, Sep 29, 2020 at 3:50 PM Cirilo Bernardo <
>> cirilo.bernardo@xxxxxxxxx> wrote:
>>
>>> That's the same reference - the problem is with the wording 'is', not
>>> 'shall' or 'must be'.
>>> The reality is that for every tool you pick that generates VRML models,
>>> the unit used is
>>> anyone's guess.  On top of that, for KiCad's purposes using meters would
>>> actually
>>> be a nuisance and would unnecessarily bloat the VRML file. Many parts
>>> often have
>>> features on the order of 10 microns; using mm or even 0.1 inches shaves
>>> off a lot of
>>> zeroes (or repetitive exponents).
>>>
>>> Cirilo
>>>
>>>
>>> On Wed, Sep 30, 2020 at 7:40 AM Seth Hillbrand <seth@xxxxxxxxxxxxx>
>>> wrote:
>>>
>>>>
>>>>
>>>> On Tue, Sep 29, 2020 at 2:33 PM Cirilo Bernardo <
>>>> cirilo.bernardo@xxxxxxxxx> wrote:
>>>>
>>>>> Oh, I wish VRML specified meters - that would have made life much
>>>>> easier.
>>>>>
>>>>
>>>> See
>>>> https://www.web3d.org/documents/specifications/14772/V2.0/part1/concepts.html#4.4.5
>>>> This reads pretty clear to me.  Was there a different reference you are
>>>> referring to?
>>>>
>>>> -Seth
>>>>
>>>> --
>>>> [image: KiCad Services Corporation Logo]
>>>> Seth Hillbrand
>>>> *Lead Developer*
>>>> +1-530-302-5483‬ <+12126039372>
>>>> Davis, CA
>>>> www.kipro-pcb.com    info@xxxxxxxxxxxxx
>>>>
>>>
>>
>> --
>> [image: KiCad Services Corporation Logo]
>> Seth Hillbrand
>> *Lead Developer*
>> +1-530-302-5483‬ <+12126039372>
>> Davis, CA
>> www.kipro-pcb.com    info@xxxxxxxxxxxxx
>>
>

-- 
[image: KiCad Services Corporation Logo]
Seth Hillbrand
*Lead Developer*
+1-530-302-5483‬ <+12126039372>
Davis, CA
www.kipro-pcb.com    info@xxxxxxxxxxxxx