Convincing architectural visualisation, especially if you are aiming at photorealism, requires good vegetation models. Luckily, there is no shortage of high-quality tree and plant models around. These include the Evermotion, Xfrog, Mentor, and iTree collections, just to name a few.
But what if you’re after a very specific, hard-to-find species, or if you want to push the quality of your vegetation one notch higher? A lot can be achieved in generic modelling applications, but a better, faster and more versatile option is to invest into a dedicated plant-modelling solution.
Again, no shortage of options here, including some free ones. In this comparative article, I will focus on two applications that stand out from the crowd: to my left, unvanquished veteran Broadleaf by Onyx Computing, to my right, cocky upstart Exlevel’s GrowFX.
This is not intended as a fully fledged review but as a series of pointers to help readers decide which of these tools best matches their needs.
For the sake of transparency, let me mention that I own licences both of Broadleaf (which I bought) and of GrowFX (which I won at a competition). The developers were not involved in this article and did not provide any test versions. However, I did submit a draft to them ahead of publication and took their comments into account in this text when I felt this was justified. I should also point out that, even though I have a decent command of both apps, I do not consider myself an expert in any of them and am far from having exhausted their capabilities.
Before we get dug in, it has to be said that both Broadleaf and GrowFX are capable of outstanding results in the right hands. Below are two examples of the modeller in action. The Ponce House image includes mostly Broadleaf trees whereas the Graticule House image (the autumn one) was done exclusively with GrowFX trees.
Both are parametric modellers that give users control over the general shape and architecture of their trees but keep these constrained by certain rules. Indeed, on the surface, there is little difference between the models generated in these apps.
One first difference between the two solutions is that Broadleaf is both a standalone application and a 3ds Max plugin whereas GrowFX is a 3ds Max plugin only. So if you’re a C4D, Modo or a Blender person, you’re probably wasting your time reading this.
Another big distinction is that GrowFX was conceived as an all-in-one solution, allowing the creation not just of broadleaf trees but also of evergreens and palms down to individual flowers. Onyx, by contrast, has developed a suite with discrete applications for the creation broadleaf trees, palms, bamboos, conifers, grass and flowers. If you need the ability to model all these different types, you will have to pay $595 for the Garden suite ($695 if you want the 3ds Max plugin) against $325 for GrowFX, making the latter slightly better value. On the other hand, if you only need broadleaf trees or conifers, you can get Broadleaf alone for a mere $195. Onyx also offers various combinations of apps at various prices.
To me, the main strength of Broadleaf lies in its tree library. The app ships with 200 plant setups and their individual textures. Broadleaf lets you model trees from scratch, but most users would start by loading, say, a plane tree and tweaking it until they achieve what they are aiming for. At least that’s how I’ve been using it. The library allows you to generate endless variations of trees fast. Most of the default plants are rather low poly and feel “thin”. But just by upping the leaf density, very realistic results can be achieved.
The advantage of this huge library is unfortunately offset by what, to me, is Onyx’s most frustrating limitation – its inadequate viewport. Broadleaf hasn’t been substantially updated for a while and it is showing its age. Although it allows the creation of very detailed trees weighing several million polys, it struggles to display them. The trees cannot be rotated live in the viewport but “rebuild” rather slowly if you want to change the POV. Having said that, you can remedy this to an extent by using the spline view, which only shows lines instead of meshes and is a lot more reactive.
Broadleaf’s greatest asset, as it happens, is GrowFX’s Achilles’ heel. The plugin ships completely naked, i.e. with neither library nor preset. New users get thrown in at the deep end and have no other choice but to follow one of the pretty good tutorials on Exlevel’s website in order to create their first tree. Although the tutorials are clear, this can be a frustrating experience as the software’s learning curve is quite steep.
Trees are created by plugging spline paths into one another in a branch network. Each “level” can be precisely controlled with direction modifiers. In addition, almost any of the myriads controls can be influenced by another (for instance, the circumference of a branch can be used to control the length of the twigs or the distribution of the leaves that grow off it). This, for instance, makes it possible for a tree to maintain a realistic shape as it gets bigger or smaller (younger or older), or it can be used to constrain the appearance of blossoms on defined parts of the tree.
Something else only GrowFX has is the ability to instance any piece of geometry on branches and have them behave like leaves or twigs. This makes it easy to adorn your trees with custom made fruit, pine cones, complex flowers or simple buds. In the latest build of the software, these instances can even be scaled.
The application also allows the use of arbitrary geometry to cut into the trees, or te be used as guides for plants to grow around, making hedges and climbers possible. (Onyx has a more basic pruning tool, which allows the cutting of specific branches, something GrowFX doesn’t allow.)
GrowFX’s metamesh option, introduced in the latest version, allows the creation of branches that naturalistically fuse into one another and into the trunk. Metameshes can be painfully slow to compute, but complex networks of roots done that way are a thing of beauty. The branches of Onyx trees, by contrast, are just interpenetrating cylinders, which look fake close up.
Overall, GrowFX provides a lot more controls than Onyx Broadleaf, which leaves more to chance. It is a more refined, more powerful yet also vastly more complex and intimidating solution. Although you don’t need a full command of all the parameters to build decent trees (I have barely scratched the surface myself), you do if you aim to achieve a very specific result. The wealth of controls also makes building a tree a time-consuming affair when Broadleaf allows you to churn out entire forests in a blink. In fact, GrowFX is so complex, with so many windows and parameters, that it is easy to lose the overview over a tree you’ve made. This is the kind of application that would really benefit from a node workflow.
While Broadleaf is a lot more user-friendly, the flipside is that it makes it quite hard to achieve exactly what you want. Instead of giving you full control, Broadleaf lets you influence a tree’s general aspect by nudging some of its characteristics in this or that direction, often via percentage sliders.
As a younger app, GrowFX has a fresher, more modern UI than Onyx’s, although, as a plugin, it is constrained by the limitations of Max, particularly in terms of viewport speed. In Max 2011, orbiting and refreshing a 4m-poly free is neither fun nor fast (it is marginally better in 2012 due to some constraints in displaying very large objects as opposed to large quantities of objects).
I won’t go into details about things both applications do equally well, like generating wind animations or creating both square leaves (for use with opacity maps) and geometry leaves (which in both cases result in heavy meshes that never look very good up close).
One thing to bear in mind if you create models for a living is that Onyx’s licence does not allow the redistribution of Onyx trees, either as free or as commercial models. I have put a few of my GrowFX creations up for sale here and will continue to do so, but you won’t find any of my numerous Onyx trees for that reason. They can only be used in your own projects.
In lieu of conclusion, I would say that both applications yield very good results. Broadleaf is lot faster but harder to control precisely while GrowFX is more powerful, more accurate, but a lot more time consuming and difficult to learn. Thanks to its metamesh and instance mesh options, the output from GrowFX also enjoys a non-negligible qualitative edge over Broadleaf, especially if your trees are meant to be shown in close-ups.
It is hard to understand why Exlevel decided to ship GrowFX without a library (though the latest version now has the ability to save presets) as this would have given it the upper hand over Broadleaf. I cannot imagine many architecture visualisers investing the time needed to generate decent GrowFX trees, let alone a full library covering a number of species, ages and seasons. As things stand, the two apps will therefore appeal to different audiences without really managing to encroach on their competitor’s constituency.
If you want to generate large quantities of beautiful, botanically plausible trees, don’t care to spend days buried in a manual, and have the money to hand, go for the full Onyx garden suite. If you’re a Max user, want full control over all aspects of your trees, including fruit, flowers and buds, if you want superior meshes with branches merging properly into trunks as well as the ability to sell or exchange your models, go for GrowFX. Either way, you won’t regret your purchase.