kicad-developers team mailing list archive

[Cirilo Bernardo <cirilo_bernardo@xxxxxxxxx>]

----- Original Message -----
> From: Lorenzo Marcantonio <l.marcantonio@xxxxxxxxxxxx>
> To: Kicad Developers <kicad-developers@xxxxxxxxxxxxxxxxxxx>
> Cc: 
> Sent: Wednesday, August 1, 2012 3:13 PM
> Subject: Re: [Kicad-developers] Realistic 3D Rendering
> 
> On Tue, Jul 31, 2012 at 05:24:06PM -0700, Cirilo Bernardo wrote:
>>  I agree this type of 3D rendering is only EyeCandy, but the marketing types 
> love it. (Ooh! Aah! How awesome! but from the engineers you hear "what use 
> is that crap?")  So I think in the future KiCAD will benefit from it 
> because these shiny things actually get people to hand over money for 
> development.
> 
> If he want to do eyecandy it's his time. Tried it, wasn't useful:P
> 
>>   Yes, STEP is what we really need to support but as I outlined months ago, 
> it should be possible for KiCAD to provide generic support for any MCAD system 
> and the tools themselves need to be separate from KiCAD because it just makes no 
> sense to make an ECAD dependent on an MCAD.  I'm waiting for the FreeCAD 
> project to release a version which supports assemblies so  I can get started on 
> my pcb to MCAD demonstration; without support for assemblies I would simply be 
> wasting my time coding.  I guess I could always code for SolidWorks, but how 
> many KiCAD users would actually find that useful?
> 
> There actually *are* exchange format for boards designed for MCAD integration. 
> IDF3 is one of them. Only problem is that only Big Bucks Software accept them... 
> I've only seen CircuitWorks (in the SolidWorks family). And then, for 
> example, there are limitation in the 'lite' version (the full suite 
> obviously costs *even more*) like 'issues' with more than 400 components 
> and only boundary representations (which actually are sufficient 95% of the 
> times...). Supposedly there is even IDF4 (even less supported XD). So even if 
> there is a simple format for interchange what if nobody can use it?
> 
> IDF3 is a standard format (documented, too! the specs are only 41 pages) but 
> without something to read/test it developing is... well... somewhat hard XD 
> actually for the specs it seems that it was originally designed to go from MCAD 
> to ECAD too since it contains keepout areas and such things...
> 


I've read the IDF specifications (v.2 .. v.4).  They all look fairly easy (even trivial) to implement as a separate tool (for example, *.brd to  IDF converter) but to really be useful, KiCAD will need to internally support features such as mechanical keep-out zones and will also need some basic tools for manipulating features while respecting the ECAD/MCAD editing conventions - that job is in the "not-so-simple" category and even Dassault uses a separate tool to simply convert IDF to SolidWorks binary files; if you export back to IDF later, none of the editing conventions will be respected.  You *could* edit the IDF in Dassault's tool, but that's not really the MCAD model - in short, even in SolidWorks, the workflow imagined by the creators of IDF is not possible. You have to create the mechanical model via import, then as you make changes to the mechanical model you need to manually adjust the IDF files.

  IDF3 will suffice for what you describe - providing rough sizes for major component so that the mechanical engineers can package the board properly, as well as hole positions and sizes. However, IDF 3 is too primitive for other jobs since components are represented as a vertical extrusion from a footprint shape on the board - I can't use it, for example, to verify that a right-angle surface-mount LED will align correctly with a hole in the panel (this is actually an issue in a current project of mine - I basically create a SolidWorks model from an IDF3 file then replace critical components with realistic solid models).  IDF 4 addresses many of the shortcomings of IDF 3, but I get the impression that industry has abandoned IDF 4 in favor of PSI-5 (which unfortunately is not a freely available specification).   Anyway, if anyone is really keen on at least exporting IDF3 and IDF4 from the KiCAD *.brd, I can help out to make sure the files are
 generated correctly and that the SolidWorks importer works on it.  I'm not keen on spending any of my time creating IDF3 footprints or IDF4 solid models though; I'm more determined to build MCAD models so that we can export STEP files.  However, I do believe that IDF3 and IDF4 support in KiCAD are reasonable projects (any volunteers?); the reason is that IDF files help to coordinate the ECAD and MCAD work and this is important in some projects.  I think in many people's workflow, including mine, for most jobs it's good enough to do all the electronics design and then give a STEP model to the mechanical people.

> I mean, I can use librecad and I've access to an autocad copy at work, I use 
> CAM350 for other files, but I've got nothing to use for testing an IDF3 
> exporter. If there was a larger selection of tools using it (converters to cad 
> formats, for example) 
> 
>>   The MCAD model is absolutely vital in some cases where a moulded or 
> machined housing is being designed to be compact (think about mobile phones, 
> tablet computers, or the iPod).  Even where the MCAD model is not so critical, 
> having the model makes life easier for the mechanical engineers because there 
> are fewer opportunities to make mistakes in hole sizes, positions, and 
> clearances. 
> 
> Agree, fortunately I survived till now with box representations for major 
> components (i.e. for the mould you don't need the thickness of every single 
> resistor).
> 
>>   As for what use the tracks are in a 3D model, I like to imagine that in 
> the future the models will be exploited by people doing thermal analysis. Maybe 
> one day some expert in thermal analysis would like to help out.  I would love to 
> have such a new tool but I know I'll be too busy with the MCAD and other 
> work to contribute anything to such an effort.
> 
> Thermals and parasites are usually done with FEM starting from the gerbers, at 
> least here.
> 

I like to imagine that the software will be so sophisticated one day that there will be thermal models for components and tools to convert a board file to the input needed by the FEM tools (but maybe not in my lifetime ...)

> Oh and btw there is still no UI for (at least) the board thickness...
> 
> -- 
> Lorenzo Marcantonio
> Logos Srl
> 


Yes, a GUI for board thicknesses between copper layers and copper layer thicknesses would be useful in the future.  For now if you want to do something like simulate a stripline, you can only extract part of the data from a board file and the rest you have to enter manually.  I suspect most people using KiCAD won't be working with high-speed data lines and RF applications on most projects, but it's still nice to slowly build up such features.  Even in my plans for the MCAD demonstration I have notes telling me that I need to enter at least the overall board thickness and for flexibility I may need to consider copper thickness even though I can't think of any real use for it at the moment.

- Cirilo