An Interview with Terence Groening; Master of Physics

In the October, 2021 edition of Motorsport magazine I’m quoted on the importance of David Kaemmer (Papyrus and iRacing co-founder) to sim racing. While he deserves every accolade that’s coming to him, so does the rest of the team he’s worked with, because software development on this scale is truly a team effort.

Terence Groening was part of the team at Image Space Incorporated while I worked there. This quiet and unassuming individual is responsible for what is widely regarded to be the most realistic physics and tire models in sim racing. He built the Sportscar GT, Electronic Arts F1 (PC), EA NASCAR Thunder (PC), rFactor and rFactor 2 physics and tire models, and now joins iRacing in an exciting move that will no doubt push the genre forwards. Let’s meet him…

Terence! Thanks so much for doing this and congratulations on the new position at iRacing! Before we talk about that, let’s work our way back to your childhood; What could you tell me about your family and upbringing? Did your parents have a computer at home?

I grew up with three older sisters in Milford, Michigan, home to the GM Proving Grounds which is where my father worked for most of his career. He was an acoustical engineer, and was always bringing home different test cars from many manufacturers. As I got older, he did let me borrow some of them. This included some stick shifts which I wasn’t comfortable with yet. I remember stalling one car repeatedly while attempting to take a girl to Homecoming, which was rather embarrassing. And I suppose the folks at GM wondered later how the clutch on their test car got burnt up.

So my first memories of computers are a bit fuzzy. My dad did manage to borrow Pong from somebody, so I played that in my earliest years. The first computer we actually purchased was actually shared with another family, and it was the Interact Model One Home Computer, a rare computer build using the Intel 8080A chip. It had the world’s worst keyboard, an early chiclet keyboard which required several pounds of pressure to type on. The graphics were capable of blasting Scrabble-tile-sized pixels onto your home television, with a resolution of 112×77, if I recall correctly. Four colors at a time, out of eight total possible. Amazingly, this small company produced a lot of copycat games and office software that kept me entertained for years, even after we moved onto an Atari 800.

Now I already knew this computer was developed in Ann Arbor, but I just discovered an interesting bit of personal trivia. The computer was originally developed at 204 E. Washington St, which is amusing to me because the longtime office of Image Space Incorporated was almost precisely across the street at 209 E. Washington!

That’s fantastic! Such a small world! It’s great that some of your earliest memories seem to be related to computing and video games. Did you pursue programming during your education? How early did you know what you wanted to do?

My mom enrolled me in a Basic programming class one summer when I was probably 8 years old. That might have just set my career path right there. I didn’t do much programming on that Interact computer, but I did write a fair amount of Basic programs on the Atari 800. Some were graphical, some were simple text-based adventures following in the style of Zork. I couldn’t get the performance I wanted for graphical games, so my dad bought me a book on programming the 6502 chip. I’ll be honest – I couldn’t make heads or tails of it at the time; I think I was a bit too young for assembly language at the time!

At the end of high school, I was accepted at the Engineering School at the University of Michigan, but I didn’t pick my Computer Engineering major until after the first year. At the time you were really supposed to take Pascal rather than FORTRAN if that was your path, so I had to take one of my programming classes without the proper prerequisite. But I picked it up on-the-fly, and realized this career was a fairly natural fit that I could also enjoy.

What was your first job in the industry and how did you end up with ISI?

My first job out of college was with StorageTek, a company that had all sorts of storage technologies, including robotic tape drives. Yes, a robot arm would pick cassettes out of a catalog and put them in a drive. Very interesting at the time, but as a junior programmer, I was really only responsible for small components of the cataloging software. Luckily, one of my colleagues there was friends with Gjon Camaj, co-founder of Image Space Incorporated, and I was able to secure an interview with him.

I spent almost 20 years with ISI, with many products and adventures along the way. We were a third-party developer for EA Sports for many years, and then developed the in-house products rFactor and later rFactor 2, which were labors of love. And then I seamlessly transitioned to working for rFpro which is based in the UK. rFpro started out by packaging up ISI’s rFactor product into software that could be used in Formula 1 simulators, and grew from there. It is widely used by many different forms of vehicle racing now, and is also used to train autonomous vehicles.

After several years at rFpro, I was contacted by iRacing recently and became intrigued about joining forces with some legends, so to speak. :)

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I really enjoyed working with you at ISI and I’m delighted for you to be joining iRacing. At ISI I’d be in a meeting and mention something, or shoot you a random email, and then often see the idea I’d had appear in the build notes a month or two later. The most under-utilized one that I value the most is being able to save races and resume them via the replay feature. It’s something Codemasters just added, working in the exact same way with F1 2021.

I remember seeing your name in the Sportscar GT manual. Was SCGT your first sim racing product? Looking back, how do you feel about it?

It was the first one I worked on, yes. When I first arrived at ISI, it was already in development and if I recall correctly it was going to be licensed and branded as IMSA (USRRC – Tim). The vehicle dynamics at that point were essentially the same as ISI’s previous title Zone Raiders, an early 3D game featuring vehicular combat with something like a hovercar. It was very fun, but the model was not appropriate for a product focused on racing (regardless of whether it leaned towards simulation or arcade). I thought I could whip something up that resembled the physics of a four-wheeled car, and with a little guidance from my dad and his endless knowledge of all things automotive, I think I succeeded.

I still love Sportscar GT and fire it up on occasion. And we loved working on it! It was a small team of talented, enthusiastic people, and many interesting careers really took off during that development cycle.

Yeah I think you did a fantastic job. Gjon told me that the reason it became a modding platform was because after Virgin sold out to EA they slightly delayed it and ISI moved a lot of parameters into text files for easier editing, then left them that way for release. And so, in-depth modding was born!

How did you feel about the way modding took off with SCGT and the EA Sports F1 and NASCAR titles?

I don’t recall it being particularly intentional, but it was certainly easier for us to tweak files in plain text! We were pleasantly surprised at how much work the community would put into it, and we enjoyed downloading and racing those efforts. And it broadened our own horizons about what was possible with the existing code!

Which simulation was your favorite?

Oof, you’re going to put me on the spot? While I spent a fair share of time in the Zen that was GPL (Grand Prix Legends), but I’d have a hard time beating the enormous variety of racing offered by the original rFactor. Of course, I’m totally biased! We made the simulation that we wanted to make, one where our own clever artists and the incredible modders around the globe could share their masterpieces.

Yeah, at the time the idea behind rFactor was amazing. And really, it still is. Great timing, too, as Papyrus had shut down and there was a gap in high-end racing simulation development until the iRacing launch a few years later.

You mentioned primarily being involved with vehicle dynamics. What other major features did you work on for ISI?

Apart from programming the vehicle dynamics model in the ISI products I did dabble in some AI and graphics programming for Sportscar GT, significantly improved the multiplayer code for rFactor, and was in general charge of the architecture throughout most of my career. Certainly I’m proud of much of this work, including the complex tire model in rFactor 2 even if was perhaps too difficult to mod!

Yeah. Not so well timed! I have to admit being a little frustrated seeing many talented modders choosing to either stay with rFactor 1 at first or move over to Assetto Corsa. A couple of factors such as the difficulty of modding and the packaging system made rFactor 2 stagnate for longer than I would have ever expected, until the decision to switch focus under Studio 397 to fully-licensed content and allow modding as well.

What kind of things do you see missing from sim racing today?

Honestly, I haven’t spent a ton of time in sim racing over the past few years, so I’m playing catch-up at the moment. What I have felt in the past is that nobody was really capturing the true feeling of driving in changing conditions, despite some valiant attempts. There are all sorts of changes, from the changing properties of rubber in a tire through its heat cycles (i.e. it’s not purely a simple change in a friction coefficient somewhere), or the subtle ripples appearing in asphalt braking zones, or the much bigger changes happening on a dirt track. And drivers have to adapt to all sorts of unexpected behavior in real life. There are fascinating games that focus on some aspects, you know, like Spintires or BeamNG, but they aren’t sim racing. We’re getting closer to melding the best features of all these products, but we’re not there yet.

I know you’ll have had to look at that a little bit during your time at rFpro as it’s how F1 races are won these days. It’s quite exciting to think the at-home sim racer has probably only just touched the surface in simulating those kinds of dynamics. It’s definitely an area for growth.

When I joined iRacing back in 2005 (ISI was 2010 onwards) it was such a weird feeling. I knew and could remember all the work these people had done in older racing sims sometimes better than they could. Going out to lunch and hearing Dave Kaemmer and Shawn Nash talking physics was utterly mind-blowing. What most excites you about joining iRacing?

I’m not sure. I think they promised me a free t-shirt or something.

But seriously, it felt like the right opportunity to work with these people focused on making the best sim in the world. Although the features that I’ll be working on are top secret (even to me at the moment!), I’m looking forward to contributing to something that lots of people will enjoy.

I still have my iRacing t-shirts! Honestly, I can’t think of many people who fit the mold for me of ‘unsung hero’ better than you. To have been largely responsible for the physics that are at this time generally recognized to be the most accurate across the largest number of vehicle types is something I truly hope you’re more than proud of. Thank you so much for your contributions to sim racing.

You are too kind, but you’re welcome nonetheless. Thank you for the nice chat, Tim, and I hope to talk again about both of our future exploits!

With more than twenty years of physics development under his belt, I think Terence is one of maybe only three or four individuals I would hold in as high esteem for that area of sim development as David Kaemmer. What’s interesting, perhaps, is that the community barely even knows his name or what a difference he’s made to the products they love, because without Terence you could argue we may not have seen ISI go as far, have not seen modding communities spring up, certainly never seen SIMBIN, Sector3, Slightly Mad, Reiza, and many other studios and individuals that learned their trade or first piqued interested to develop their own simulation because of his work.

I’m sure he’ll now slip back into the background. Quiet. Unassuming. Astoundingly modest. When I first walked into the offices at ISI and saw the huge Grand Prix (1966 movie) poster above his desk, I knew we’d get along.