Interview with Rob Guglielmetti of Renfro Design Group, Inc.

Interview with Rob Guglielmetti of Renfro Design Group, Inc.

Rob Guglielmetti, Director of Information Technology and Lighting Calculation Programming and Analysis, talks to CGarchitect.com about his experiences in the CG and lighting analysis field.


CGA: Could you introduce yourself and tell us a little bit about your role at Renfro Design Group Inc.?

RG: Certainly. My name is Rob Guglielmetti, and I am the Director of Information Technology and the Lighting Calculation Programmer & Analyst for Renfro Design Group, Inc. We are an architectural lighting design firm based in New York City. My boss, Richard Renfro, has been a lighting designer for over twenty years, and is immensely interested in applying technology to the art of lighting design. I have been pleased to be able to help the firm devise a strategy for doing just that.

CGA: Tell us about your background. How did you get into the Architectural CG industry?

RG: Hmmm. That's a rather circuitous journey, to be sure. It goes like this: bicycle mechanic - actor - standup comedian - theatrical lighting designer - architectural lighting designer - CAD manager - MIS manager - lighting calculation programmer & analyst.

My background is in the theater, but about nine years ago I decided to get into Architectural Lighting. Lacking a formal background in Architecture I taught myself AutoCAD, largely to have something appealing on my resume. I ended up becoming fascinated with computers in general, and computer lighting design technology in particular.

I wound up at the former Fisher Marantz Renfro Stone, where then-partner Richard Renfro & I started to work together with Lightscape. We applied CG technology to study some louver designs for the Museum of Fine Arts in Houston, TX. This was the first time we really relied on the computer to quickly analyze several schemes. We were quite happy with the capabilities and the results. When Mr. Renfro started his own firm in 1998, I followed him to his new office and he hasn't been able to get rid of me since.

CGA: How did you become involved with the lighting design aspect of the industry?

RG: Well, I guess it's more a matter of getting involved with the CG aspects of the lighting industry. We embraced CG as a way of helping us do our jobs as lighting designers; we didn't evolve into lighting designers from computer artists. Our hearts are in lighting, first and foremost.

CGA: How is Renfro Design Group Inc. using CG software to enhance the services offered to its clients?

RG: We have for the moment settled on Autodesk's Lightscape for all our work. We use it primarily for calculations, and I think this is the fundamental difference between our work and that of many of the talented artists you see out there. We strive for photometric accuracy and speed. The tradeoff is that our renderings are not always shiny and spiffy. We use the computer to construct "electronic foam-core" study models.

In a nutshell, we use CG to better understand a building. Then we use CG to better understand our own lighting design solutions for that building. Lighting design is equal parts art & science. I suppose you could say we draw on Mr. Renfro's experience to devise a solution, and we use CG to confirm it, to understand it, and to assist in describing and illustrating it to the client.

There are a multitude of calculations that must be performed in the daily work of designing the lighting on a project. Many can be performed with a simple calculator, but there is always an area or two that will involve some complex geometry, or a sensitive area, where the computer can help us. That is where CG comes into play. We will create models to study the space and the lighting.

We have invited the client to our office to review these models on-screen, in real time. The OpenGL engine of Lightscape is well-suited to a rapid, informal walk-through of a space. We have had architects discover things about their own buildings as we look at the models together; it's just a wonderful collaborative tool when used in this manner!

CGA: How have you seen the architectural CG industry grow, with respect to lighting, since you have been involved in the industry?

RG: Many manufacturers are embracing the technology. The growth of the Internet has helped; most manufacturers have websites with photometric data available for download. Just a few years ago, one generally had to make a bunch of phone calls, and wait for a disk in the mail. Now I can expect to get photometric files for any given calculation right off the Internet.

Several manufacturers have gone even further, creating 3D blocks of their luminaires for use in programs like Lightscape. Two companies that come to mind are ERCO and Litecontrol.

CGA: Where do you see the future of architectural rendering and how will new rendering technologies affect that future?

RG: This may be a case of stating the obvious, but as computers continue to get faster, we gain a twofold benefit.

For one, the existing technology will work better because we will have to wait less for the calculations. Time is the enemy when looking at multiple complex designs, and as we gain more CPU cycles per second, we save time.

Second, the faster CPUs, expanding RAM standards, and better display technology will place new capability in the hands of designers, as the software companies exploit the capability of better hardware.

CGA: Where do you see the future of CG lighting design? Are there advances that you would like to see made to make to the CG end of lighting analysis easier?

RG: Good question. Many LD firms are still using programs like AGI and Lumen Micro, which until recently lacked any graphics capability. Even in their current iterations, the capabilities of the rendering engines and/or the modeling abilities of these programs are lacking. The reason many firms use them is that they are fast and easy. They were created for lighting designers, not for animators. As a result, the ability to get lighting data - illuminance and luminance data - is built in; it's assumed to be a requirement. And it *is*, from a lighting design standpoint. That's the single biggest thing I'd like to see in the higher end radiosity packages, is better data extraction and reporting tools.

CGA: GI and radiosity have become fairly commonplace over the past five years, what do you feel are the current limitations of these technologies for achieving accurately lit scenes?

RG: The computer screen is woefully inadequate, in terms of dynamic range, compared to the human eye. We need better ways to convey in print and on screen the "feeling" of a space, not just the "look" of a space. This is the most important thing to me. In fact, this is one reason why we stray away from "photorealism" in our renderings. There is currently no such thing as a WYSIWYG lighting rendering! The studies in perceptual rendering are a positive step toward trying to better apply the tools we have to represent reality. As computers have become capable of calculating reality, so too must our display & output technology step up to the challenge.

Another big problem is that each technology can account for only a subset of all the lighting phenomena. True radiosity cannot account for specular reflection, for example. Lightscape tries to make up for this by allowing for a raytracing pass after the radiosity has completed, but you're getting a rendering that "looks" right but is not 100% photometrically accurate. Lightscape also cannot calculate diffuse transmission. As a result, we have to rely on physical mockups for our studies of various glass used on a project. This is a huge area of concern on a museum project, that my firm's current CG suite cannot help us with. The fabulous program Radiance can account for most of this phenomena, but is quite complex and lacks the interactive feedback we get from Lightscape/OpenGL. We intend to incorporate Radiance in the future as it allows some more capability, but the learning curve is an issue in a production environment.

CGA: What have been your biggest challenges both past and present, with regards to computer renderings?

RG: Educating the client about what these renderings represent. Explaining that our renderings are not pictures of reality is the constant struggle. Technically, the challenge has always been a matter of CPU cycles. We always wish for more cycles, and more memory, as we move forward and press the limits of the technology.

CGA: What advice would you offer a lighting designer starting with CG lighting design and rendering software like Lightscape?

RG: Read the manuals. Run through the tutorials, as they are a good primer to the various techniques needed to efficiently work with the program. Understand that Lightscape is a photometric & physically-based program, so make your models and your light sources precise and to scale. Use light loss factors and apply them to your photometric files' multipliers, because at the moment that's the only way to prorate the luminaire output to true, maintained values in Lightscape. (This is, in my opinion, a serious limitation. The multiplier is buried in the .IES file, so it's easy to miss it. We generally create a master luminaire schedule for each project, and make copies of the original .IES file, which gets modified per our needs. The modifications are all documented in the luminaire schedule for easy reference.)

CGA: Which rendering are you most proud of and why?

Well, most of ours are not much to look at. In the office we get more excited about a falsecolor rendering or a grid of illuminance data than anything you'd see here from the other artists. We're a strange lot!

CGA: What software do you currently use and have you used in the past for computer renderings and why have you chosen those particular applications?

Well again, we don't use CG specifically to generate renderings, but on the whole we use Lightscape version 3.2 for all our work. At this point we have a workflow strategy in place with this application that allows me to get good lighting data from models as quickly as I ever could using the more traditional programs, such as Lumen Micro or AGI. I guess I've already stated why we like Lightscape: great interactivity, capable radiosity engine, excellent geometry importer.

CGA: What do you not like to see in computer generated architectural work?

I'm not a computer artist, I'm a lighting designer. I don't think it's fair to cast aspersions on the post process lens flares and other accoutrements often seen in the work of folks with too many Photoshop plug-ins on their hard drives, but then, I guess I just did. In all seriousness, that sort of thing is great, as long as it's qualified. But my interest in CG is in the ability of computers to compute and display reality. Current technology is a ways off from truly being able to speak for nature, so all these renderings that are obvious victims of post processing just seem to push us back further in terms of public perception. Everyone loves the eyewash, until they find out they've been duped - again. So, if you're going to present a rendering that's been seriously facelifted, let people know.

CGA: What tip(s) can you give our readers to improve their architectural renderings?

Since my renderings are not trying to visually impress so much as prove some math, I'm not sure anyone's hanging on the edge of their seats for my answer to this one! From a lighting design standpoint, the only advice I'd offer is to be honest in what you represent. It all goes back to the discussion on dynamic range. If you have a calculation that indicates a space is dark, and the client wants a bright one, don't crank up the brightness to create a "bright" rendering. In short, don't lie. As a lighting designer, use your computer renderings as tools; tools that belong in a larger toolkit that includes good verbal communication and experience. These renderings cannot tell the whole story. If you allow them to, your client may fill in the blanks incorrectly and both of you will be unhappy.

CGA: What is your favorite link to visit on the web? (not necessarily CG related)

Google, because it can take me to wherever I want to go at that moment. Currently, it's my favorite search engine, my default homepage, and my starting point on the web, whether I'm looking for information on lamps, computers, airplanes, or whatever strikes my fancy at a particular moment.

CGA: Which/What web based resources that you have found the most informative?(provide link)

www.lightscape.com - For a Lightscape user, Lightscape's website is quite good. Particularly the discussion forums, where you can listen to and chat with many accomplished CG artists.

radsite.lbl.gov/radiance/HOME.html - The Radiance home page, for more information about the most photometrically capable CG program in the world.

www.schorsch.com - George Mischler's site. He wrote a front-end to Radiance and even improved the Win32 binaries for us UNIX-impaired types who'd like to experiment with Radiance!

www.light-link.com - A good starting point for light fixture manufacturer research. This site is a large database of manufacturers which you can search, and if the company has a website you can link to it from here.

There are links at all of these sites to even more exciting websites, including papers on perceptual rendering and the like. You could also use Google to zero in on good stuff.