As a long-time Lightscape user and someone who has adopted Lightscape into his daily workflow for lighting design analysis, I looked forward to getting my hands on Autodesk VIZ 4®. Over the last few years, the Lightscape Visualization System was purchased by Discreet Logic, and then in turn became part of Autodesk's Kinetix division. Speculation abounded about Lightscape's future.

Many users had seen the obvious interest there; 3DStudio (now known as the targeted applications Max and VIZ) lacked global illumination. Lightscape had a capable radiosity-based GI engine - more than capable. Many surmised that Lightscape would be "plugged-into" 3DStudio, and we'd all have to watch Lightscape become a stripped down feature in a larger program, a program with an entirely different mindset and target audience. Some thought this to be a bad thing. I for one was curious and hoped this would be a good thing for me.

On the surface, I'd have to say it hasn't.

There is good and bad to report here, but first off, I want to stress that this is an analysis of the lighting analysis tools in VIZ 4. More specifically, it's a review of what has changed since Lightscape 3.2, and a little optimistic gazing into the crystal ball. Jeff Mottle has provided an excellent overview of VIZ 4 elsewhere on this site, including a discussion of the lighting features. I'm interested in the bottom line as it relates to the lighting designers out there that are using Lightscape 3.2, or perhaps AGI or Lumen Micro & were wondering about a change.

I had the privilege to be on the alpha & beta test team for VIZ 4, the new binary home for the program-formerly-known-as-Lightscape. The quick summary is that yes, radiosity has been incorporated into VIZ 4, and many of the lighting analysis tools that were present in Lightscape are gone. We lost adaptive subdivision, block substitution, useable falsecolor renderings, command-line utilities, luminance/illuminance grids, and the wonderfully finite control over the process parameters we had in Lightscape 3.2. You can still obtain luminance & illuminance summary & point info by clicking on a surface, but that's about it. Falsecolor renderings are still an option, but they render with no color legend. Without a reference to what the colors mean in terms of light level, falsecolor renderings are fairly useless. One could use an image editing program such as Photoshop to add the scale in as a post-process, but I'd say what was already a tedious process just got harder.

What's new is a daylight system that can be animated; once you set up the daylight system (an assembly of "lights" that simulate the direct sun and sky component), and the location and north orientation parameters, you can ask VIZ to simulate an entire portion of a day, at increments you specify. VIZ will generate a radiosity solution & rendering for each frame, making the animated sun study much easier to do than it is in Lightscape. Anyone who has done this on a regular basis in Lightscape has probably run into me in line at the insane asylum when picking up your meds. It's a tedious, error-prone process. The animation-centric VIZ has scored some major brownie points with this feature.

The ability to model diffuse transmission is now a reality in VIZ, something else we did not have in Lightscape. But this brings me to a major issue (not at all Autodesk's fault): The interaction of light with medium is a fantastically complex process. Any attempt by a computer program to emulate these behaviors must be validated before one can trust the results. My co-workers & I spent a lot of time validating the Lightscape radiosity engine. We trust that it can do some things well, and we work within its limitations. Now that VIZ 4 can simulate additional phenomena, this represents a new frontier that must be explored - from a validation standpoint - before really committing to VIZ 4 in a production lighting design workflow. So although we gain some tools there, it's almost a catch22 because we can't really use them until we invest a bit of time validating them. I have supplied the VIZ developers with some of my firm's quantitative analyses, but they focus on Lightscape's abilities. Validation of VIZ 4's new abilities has yet to be conducted.

A couple of new features, "regathering" and "light painting", are curious. They really indicate the direction of the program and I guess the intended user base. These are features that purport to work around the problems inherent with radiosity such as shadow leaks and artifacts caused by poor modeling techniques. These features are essentially post-processes, with light-painting being the most offensive to me, as a lighting designer. This tool allows you to "add or remove illumination" as necessary, to "touch up a scene". If only it were that easy in the field! It's akin to turning up the brightness on a hopelessly under-lighted scene, or other such god-playing antics. These have no place in a serious lighting analysis & rendering tool, but then again VIZ 4is not that at the moment.

Radiosity is all about meshing, especially when it comes to any attempt to accurately simulate the distribution of light in a space. Sadly, we no longer have a meshing scheme driven by adaptive subdivision. This was a wonderfully intuitive and efficient way of getting the most bang for the computational buck. VIZ 4 requires you to accept a global mesh setting, or to manually set the mesh parameters for each surface. Neither method is really suitable for serious lighting analysis. Oftentimes, a relatively large surface wants to have a variable mesh density. This was almost automatic in Lightscape 3.2; in VIZ 4, it's impossible. If you think of every mesh vertex as a light meter, you can quickly see how inefficient the current meshing schemes are in VIZ 4. Improvements need to be made in this area for VIZ 4 to be truly viable for serious lighting analysis on complex models. Admittedly, for a small or simple model, one could make the global meshes dense enough to get accurate data without overwhelming the processor or memory.

Perhaps the biggest loss to me is that of block substitution. This feature is in my opinion one of the most impressive abilities of Lightscape 3.2. I routinely use AutoCAD to create accurate lighting layouts, then import them into Lightscape using block substitution to swap a simple circle for a set of 3D geometry, with materials and IES file properly attached. It enables me to quickly create multiple lighting scenarios with an accurate modeler and import them to Lightscape for analysis. This was certainly not something I expected to lose, given that AutoCAD is made by the same folks as VIZ 4. I was told by the developers that block substitution is an advanced feature, used by very few people. I propose Autodesk put block substitution back in and I'll write the tutorial on how to use it. It may be an advanced feature, but it's amazingly useful and practical, and it sets us ahead of the rest - like walking upright.

Limited as the lighting grids are in Lightscape 3.2, they are even less useful in VIZ 4, since they no longer exist. Every serious lighting analysis program, such as AGI and Lumen Micro, has the ability to portray luminance or illuminance data in a user-specified grid in the model. Lightscape 3.2 had a crude implementation of this, but lacked the ability to do anything but display the data on screen or in a rendering. Most lighting applications also allow for the export of this oft-voluminous data to a text file for further manipulation and reporting. I was hoping for this ability in VIZ 4, but instead discovered that the limited ability Lightscape had was removed altogether.

One other strength Lightscape has is in its command-line tools. From a batch file I can control everything about a Lightscape 3.2 simulation, from the layer state of a solution file to the color of the sky in a rendering. Through creative manipulation of batch files I can exercise rigid control over a series of lighting simulations, and guarantee accuracy and consistency through a project. Sadly, these tools are absent in VIZ 4.

So long block substitution, adaptive subdivision, lighting grids & command line functionality, we hardly knew ye.

So what is the good news, besides the animated sun studies? Well, simply this: a new foundation. I've never been accused of being an optimist, but I see a couple of positive developments in the evolution of Lightscape to VIZ 4. VIZ 4 includes MaxScript, a fully functional all-access pass to the inner workings of VIZ. Proper use of MaxScript could bring back a lot of the lost pieces of Lightscape, and even add new features. Perhaps there's a way to use MaxScript to emulate the block substitution feature, or to extract illumination data to a text file.

Anyone saying "Lightscape was swallowed by VIZ" is oversimplifying things. It wasn't a matter of taking Lightscape's radiosity engine and putting it in VIZ, it was a ground-up rebuild. Features were not removed, they simply didn't get added in, due to time constraints. I'm unhappy that the features I use most were the ones deemed least important (to the largest market segment), but business is business I suppose.

Autodesk is offering a reduced upgrade price for Lightscape licensees to go to VIZ. They are knocking $400 USD off the price of a copy, bringing it to $1495 USD. Quite simply, it's a lot of dough. It's a lot of program too, but much of the functionality will collect dust if you use Lightscape purely for lighting analysis. As a lighting designer, the price would have to be a lot lower for me to justify the upgrade. But I am intrigued by the possibilities for the future of this program. I encourage lighting designers to write your VIZ Congresspersons, lobby for the features we want & need; they might just listen. There is an opportunity there for third party developers and manufacturers as well; perhaps through the third party channel lighting designers will be able to get what we need to make VIZ 4 a viable lighting tool.

- Rob Guglielmetti

Rob Guglielmetti is a Lighting Calculation Programmer and Analyst for Renfro Design Group, Inc, an Architectural Lighting Design firm in New York City. He has been a Lightscape user since 1996.


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