STEP metadata / Pointwise and Python

[Tim Jim]

Hi,

I was wondering whether the ability to add metadata, such as geometry names, was added to STEP exports in the end? I was checking this post and it seemed like some progress was made two years ago.

The reason being that I am currently programmatically creating geometry and would like to mesh them in an automated manner. However, the geometry names seem to be lost after importing the STEP into meshing software such as Pointwise. If it is possible to maintain the names, it would be easier to extract and specify meshing parameters to the various parts of the aircraft within a Python script (where I've kept all the names etc. from building the geometry in the first place).

Kind regards,

Tim

[Rob McDonald]

I haven't had time to follow through with the STEP metadata.  Trevor did a good job with it, but he was developing it for a somewhat specialized application.  I needed to think it through to make sure it captured the general intent of something I would build into OpenVSP.

That said, a while back, I added a simple metadata capability into the IGES export for OpenVSP.  It has been tested with Pointwise and it worked great.  I suggest you give that a try.

Rob

--
You received this message because you are subscribed to the Google Groups "OpenVSP" group.
To unsubscribe from this group and stop receiving emails from it, send an email to openvsp+u...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[Tim Jim]

Thanks for the suggestion. Due to the way Pointwise seems to lump together or split the components of exported geometries from both STEP and IGES files into a dizzying number of surfaces, models and curves, I've decided to attempt surface meshing with OpenVSP instead and will export the surface mesh to Pointwise through an STL for volume meshing. This process might be easier to automate than handling aircraft metadata across programs.

Kind regards,

Tim

[Rob McDonald]

Don't be so quick to blame PointWise for the dizzying number of surfaces!

When you export a STEP or IGES from OpenVSP, you are presented with a menu of options.  One of those is 'Split Surfaces'.  Turn that off -- the dizziness should go away.

Either way, Pointwise also has an example script for importing OpenVSP geometries and meshing them.  You should check that out.

https://github.com/pointwise/AircraftMesher

https://github.com/pointwise/VSP2CFD

Rob

[Tim Jim]

It wasn't a jab, I just meant that the geometries tend to be split (even with the 'split surfaces' toggle turned off). I've attached screenshots of a STEP and IGES import with no additional splitting setting turned on.

In the case of the STEP file, it is not immediately obvious (without using the GUI) which part of which component each model and quilt belongs to due to the lack of metadata.

In the case of the IGES file, the import throws errors with some of the property entities but, ignoring those errors, at least the sections are named. However, the geometry sections will still require merging, as the components seem to be divided into several b-splines each.

Thanks for the links! I have actually based my python-driven meshing script off of those particular glyph scripts.

[Rob McDonald]

Looks like you're way ahead of me on this...

Rob

[Trevor Laughlin]

Tim,

I do have a PR that may be a "safe" first step at putting metadata in the STEP file https://github.com/OpenVSP/OpenVSP/pull/99

Do you think that would suit your need? As Rob mentioned, for another project I had put a whole bunch of other data to support a structural modeling tool, but just having the names goes a long ways and seemed like a useful PR contribution. This assigns the names to the geometric set, which in the CAD tool I was using (OpenCASCADE) enables you to collect the surface(s) into a single component even if they are split. An example demonstrating the process is here in case you find it useful https://github.com/LaughlinResearch/AFEM/blob/master/examples/vsp_cfd.py

[Tim Jim]

Hi Trevor,

Thanks for the link and your efforts. I haven't had a chance to have a proper look through yet as I've been pulled onto other projects. It looks like you've added some name strings in src/geom_core/Vehicle.cpp, is that correct? This could be useful, at least to identify the parts. I'll see if I can find some equivalent way to fuse geometry sections in Pointwise.

AFEM also looks very interesting by the way!

Many thanks,

Tim