upFront.eZine #1,103: Open Source Architecture

Interview with Duncan Lithgow

Inside the Business of CAD | 5 July 2021

From the Editor

With this issue, we take our annual summer break. See you in September!

Q&A With OSArch

OSArch [open source in architecture] provides access to free and open source software for the AEC and BIM markets, as well as an umbrella for developing the software.

I interviewed Duncan Lithgow, who is one of several active community coordinators of OSArch. His passion for open source and libre software comes from the conviction that sharing is good, and that grassroots collaboration gives better results than boardroom talking points.

Ralph Grabowski: What position do you see OSArch having in the architectural design world — supporting role, minor player, major actor?

Duncan Lithgow: OSArch is about bringing a more ethical approach to the software we use in architecture, engineering, construction, and operations (AECO). We support moving the industry toward more openness and more collaboration.

At our core we support and encourage projects bringing professionals together to develop the software tools we need to do our job well. This means developing and supporting software developed as free/libre and open source (a.k.a. FLOSS) [see en.wikipedia.org/wiki/Free_and_open-source_software] and the use of open standards, such as those developed by buildingSMART, the W3C, and others.

Grabowski: How much open source software is available to the CAD world?

Lithgow: Our Free Software Directory at wiki.osarch.org/index.php?title=AEC_Free_Software_directory lists over a hundred projects, covering everything from computational fluid dynamics (such as OpenFOAM), structural analysis (Code_Aster), to presentation and document editing (Scribus and Inkscape).

My knowledge is what happens in architectural offices. There you see growing use and support for FLOSS solutions like Speckle to fix the industry’s interoperability problem.

In building physics, FLOSS projects, such as Radiance, EnergyPlus, and OpenFOAM, are tried and battle-tested as the reference standard.

Ladybug Tools and its Pollination platform sees increasing support, pulling many tools together. Those are just some of the superstars of the movement in AECO.

Grabowski: At what point are major software pieces, such as LibreCAD, Code_Aster, and LibreDWG?

Lithgow: Some projects are very mature and stable, and some projects are in rapid bleeding edge development.

Grabowski: Tell our readers about some of them.

Lithgow: QCAD Community Edition is libre software and is a quite capable 2D CAD package. They sell a commercial version, which adds some non-core functionality, such as DWG support, and help fund the development of the community edition.

Code_Aster is one of the few FOSS tools that is being developed and completely backed by a multinational company, Électricité de France, a French electric utility company largely owned by the French state. It has been developing Code_Aster over the last 30 years and then released it as a FOSS tool in 2001. At Électricité de France it is used to analyze, design, and verify new and existing infrastructure assets along their whole lifecycle.

Within OSArch, Code_Aster is one of the fundamental pieces of a structural analysis workflow that has been under development since the beginning of 2020. (See community.osarch.org/discussion/9/integration-of-code-aster-in-an-ifc-driven-workflow-for-structural-analysis.)

  1. The first part of this workflow is the definition of the OpenBIM Structural Model (OSM). The project is being developed within the BlenderBIM add-on, and is 30-40% complete.

  2. The second part of the workflow relates to the conversion of the OpenBIM Structural Model to a Code_Aster structural model, and then performing structural load analysis. This part was developed as IFC-to-Code_Aster (ifc2ca, presented at community.osarch.org/discussion/99/) and is currently 20-30% complete.

  3. Other parts of the structural analysis pipeline are not developed yet, such as

    • Visualization of structural results in Blender and other OpenBIM-enabled tools. I should note that there are FLOSS tools such as Salome_Meca that are designed for visualizing Code_Aster results.

    • Verification of structural members according to specific structural codes. This last task is quite broad and challenging to address holistically.

A special mention should be made for Adapy, a FLOSS python library, released a few months ago. It has the potential to work with Code_Aster but also other FLOSS structural solvers to be considered in the structural workflow. Adapy is still in early phases of development, yet features complete “proof of concept” examples and specific development for a user-friendly procedure to install all needed packages for performing the structural analysis on a desktop computer.

LibreDWG supports DWG, DXF, and SVG. It is just starting to be integrated into projects, so I’m not sure how much testing it has seen in real-world scenarios. It works for me inside FreeCAD. It looks like 3D DWG is really going to be a challenge. LibreDWG is not the only FLOSS-oriented DWG project, but it is the most advanced. Some solid testing and support for LibreDWG could make a huge shift in the industry opening up a whole world of legacy files to FLOSS projects.

It might sound like lots of little tools. That’s how things work outside the monoliths with their walled gardens of proprietary solutions and poor interoperability. The “little tools” approach means that as projects mature and as your needs change, you switch out parts of the workflow with something else.

Grabowski: How much of open software is being used by corporations and universities?

Lithgow: Examples of software in very rapid development are FreeCAD and the BlenderBIM add-on. We have some great examples of how companies like OpeningDesign and Open Source Ecology use free software on commercial projects. Larger companies also use both FreeCAD and the BlenderBIM add-on in aspects of their workflows. Universities are starting to introduce the software in their courses and in BIM academic research.

In their current state, they are not yet drop-in replacements for average users who want to replace an entire suite of tools offered by Autodesk, Bentley, or Dassault. However, depending on the scale of the project, the use-case the user has, and the technical abilities of the team, certain features are more mature than others and are already creating commercial value.

In other aspects, both FreeCAD and the BlenderBIM add-on have far surpassed proprietary solutions and are pioneering in areas such as native support for international BIM standards, semantic drawing generation, and cross-disciplinary support.

These technical feats, contributions to the cross-platform OpenCAD ecosystem, and forays into uncharted territory were recognized by

At this point it is very difficult to be specific on exactly what’s ready and what isn’t, as it is so context-sensitive, but development in both projects are accelerating, and we are excited to see where they go.

Grabowski: What about IFCs?

Lithgow:We have several IFC based projects: lossless round-tripping IFC files between software packages, implementing energy analysis, structural analysis, implementing cost planning, construction sequencing, and projects drawings.

All of this is working directly inside the IFC schema, deeper than any other project that I know of. We are working with buildingSMART to make it all work smoothly.

Grabowski: How is OSARCH funded?

Lithgow: At the moment we cover our costs for digital infrastructure via donations to the Liberapay platform. We plan to join a fiscal host so we can start fundraising and accelerate our work with corporate sponsors.

We do have a list of financial sponsors ready to support us, but we don't yet have a legal structure to make this possible. We’d love to hear from anyone who wants to support our efforts. We’re also happy to help anyone find projects that they’d like to support directly.

Grabowski: Where does the programming prowess come from?

Lithgow: In contrast to how I imagine most software companies work, we are not staffed by software experts from outside our field. Most programmers who support our aims are AEC professionals first and programming is either part of their work or a passion on the side.

However, being open source, programming contributions can come from anywhere. Increasingly, it makes business sense for AEC tech startups and power users within larger AEC firms to reuse free software instead of reinventing the wheel, and as a result we see many commercially funded contributions as well.

Being open source, it is easier for us to share resources and coding expertise across projects, so a little programming can go a long way. OSArch helps act as a medium through which these synergies across projects can be formed, so that together we can solve more complex problems, knowing that all our projects are interdependent in the AEC ecosystem.

Grabowski: What do you see for the future of OSArch?

Lithgow: Where this will all go is hard to know, but we’re not a organization reliant on backers or income. Maybe we’ll end up with huge influence and a generous budget to support and coordinate projects that challenge the status quo. Maybe not.

What’s clear is that the ideas we represent are not going away, and are increasingly acknowledged by industry. More and more, the most tech-savvy people in AECO rely on FLOSS to do their jobs and to develop in-house solutions.


[Duncan Lithgow was educated in architecture and construction management in New Zealand and Denmark. Now he works for a Danish architectural and engineering firm, and is learning programming.]

And in Other News

Lantek’s speciality is software for designing, costing, and cutting sheet metal parts. For its Global Release 2021, it has updates to these packages:

  • Lantek Expert CAD/CAM

  • Lantek Flex3D

  • Lantek MES and Integra

  • Lantek Analytics

  • iQuoting and Metal Shop

One of the new functions represents the new direction CAD software has been taking. Forget cloud, AI, and other topics that are trendy. Instead, less work for designers is the way to go, like this new function: Assembly to Nesting importer unfolds all the sheet metal parts (taking into account the bending tool being used), making them ready for nesting and cutting.

Other new functions include the following:

  • Import CAD files by drag’n drop, and then detect duplicate parts

  • Clean cut avoids lead-ins and micro-joints

  • Spiral cut destroys material within holes to eliminate the manual removal of scrap material

More information at www.lantek.com/us/software.

- - -

Canon’s new Arizona 135 GT flatbed plotter plots on rigid media that roll-feed plotters cannot handle — glass, aluminum, wood, MDF, ceramic tiles — and with with an optional roll media attachment it also plots on regular media like paper.

It handles media as big as 49x98" (125x250cm) and two inches (50mm) thick. Print speed is up to 368 ft²/hour (34.2 m²/hr). This Arizona model is so new that there isn’t a Web page for it yet, so I’ll direct you to the press release: usa.canon.com/internet/portal/us/home/about/newsroom/press-releases/press-release-details/2021/20210629-press/20210629-press.

- - -

C3D Labs adds Class F (fairing or functional) curves to their geometric modeling kernel. F-curves are like Class A curves, but with added optimization, such as a plough designed to minimize soil adhesion.

The company describes the development of F-curves in a three-part series starting at https://c3dlabs.com/en/blog/products/class-f-curves-from-c3d-labs-part-1-introduction-to-fairing-curves.

Letters to the Editor

Re: Overview of Engineering Math Software

Your value of Euler's Constant in upFront.eZine #1,101 is just an approximation. Here is a slightly more accurate version:

...to 10,000 characters.
            - Bill Fane

The editor replies: Did ya’ COPY'N PASTE that? [Note from editor: rather than publish all ten thousand characters, I did a screen grab.]

Mr Fane responds: No, I had a moment to spare so I worked it out in my head.

Okay, would you believe math.utah.edu/~pa/math/e.html?

- - -

As a supporter of open source software for AEC, I was disappointed to read in issue #1,100 your comment about SMath Studio that “Being free, it is not as advanced as MathCAD.”

One of the sad consequences of people thinking “You get what you pay for” is that cheap and free are synonyms for poor quality. That’s simply not true. It’s probably more accurate to say that you can’t know what you’ll get if you don’t do your homework. Researching potential solutions, free or paid, is what’s important.
            - Duncan Lithgow

Re: 2 CAD Guys Talk about the Cost of CAD

The conversation with David Stein is exactly on-point.

As we’ve discussed before, mechanical CAD is a commodity in that the dominant products function alike, do an adequate job, and have no impact on a manufacture’s profit margin. Development and innovation is nearly non-existent, and there seems to be no huge need for it.

The fact that all competitors in the business are scrambling to develop new business models — instead of new products — is indicative that the products have matured (or stagnated, depending on your outlook), and become a commodity.

Companies that were created and grown on rapid innovation always find it difficult or impossible to convert to a commodity business, and they generally abandon markets that have gone that way. Mechanical CAD is $500 to $1500 software, and I don't see companies like Dassault, Siemens, or PTC having any interest in such trivial stuff.

As always, your newsletters are insightful.
            - Jess Davis, president
            Davis Precision Design, Inc.

The editor replies: At user conferences, CAD vendors like to show off how their software was used to develop a special product, like the Square payment module or prosthetics for children, and I think to myself, “Yes, but all of your competitors can do exactly the same design.”

Notable Quotable

“Nigeria has banned Twitter entirely, which is a different way to go on Big Tech.
“Twitter responds that this is a denial of Nigerians’ human rights, which doesn’t apply to those whom Twitter decides to ban.”
- Michael Every

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