Product Review: Bionatics' NatFX

Author: by Daniel Sánchez-Crespo Dalmau

Graphics hardware is evolving at a gigantic pace. Gone are the days of low-polygon meshes; today's games allow rendering of very complex geometry and are opening the doors to representing lifelike, lush, organic environments. One of the elements that has only recently found its way to desktop graphics are realistic trees, light years away from the classical billboards found in games of yesteryear. Still, tree modeling can be a complex art: the developer must cleverly find a balance between real geometry and textured planes, often with the help of some level-of-detail processing. This makes tree modeling a time-consuming task, and results are often unpredictable. To ease this task, a number of specific tree-modeling tools have appeared. One of these is Bionatics' NatFX, designed specifically with game developers in mind.

NatFX, a Max plug-in (a Maya version is also available) that allows the rapid creation of trees and plants of various types, is the result of almost 20 years of research dealing with synthetic plant representation, growth, and visualization, carried out at the CIRAD institute in France. Essentially, the package can create all types of plants, which are encoded in a virtual DNA. By using that DNA and Bionatics' simulation technology, you can then reproduce an instance of that tree at any given age and time of the year, including seasonal changes.

Tree modeling is only one of the features found in NatFX. Once the tree is done, the package offers a variety of methods to reduce its triangle counts to real-time requirements. From a full 3D representation of a tree (typically in the tens of thousands of polygons), NatFX will construct a hybrid representation of the same tree, combining geometry and texture maps. The result? The tree shrinks down to the 1,000 or 100-polygon range, while keeping a very similar look to the high-resolution model. Additionally, NatFX can create different levels of detail (LODs) for the same tree. Beginning with the full 3D version for extreme close-ups, you can define up to three LODs of descending triangle counts. By using some clever alpha transitions, you can smoothly move from miles to meters, without perceiving any quality loss.
NatFX provides interesting features custom-tailored for game developers: from tuning the number of billboards employed to reusing texture maps to reduce memory footprint, the package really delivers in terms of features. The technology is rock-solid, creating some of the best-looking trees around. They look quite natural, tending away from the classical recursive look found in some packages.

Still, NatFX comes with a few annoying glitches that spoil an otherwise smooth ride. To begin with, the interface is not very intuitive. Ideally, artists would be allowed to work with concepts they are familiar with, such as color, size, and age. Sadly, this is not the case with NatFX. Artists must understand how the program works in order to exploit its full potential. Actions such as setting the desired number of triangles, modifying already existing trees, or changing the color of the leaves would seem logical in a tree-designer mindset. And yet the software fails to present its workflow in a simple, coherent way.

Last, NatFX's advantages come at a price. At a base license of $990 (with 10 plants) and an additional $100 per extra tree, NatFX is a bit on the costly side, especially considering you have no way (other than purchasing trees from Bionatics) to expand your tree collection. There is no editing tool to allow users to create variations or completely new species. So, if you need to create a varied collection of trees, you are certainly going to pay for it.

Still, NatFX is one of the best tree-modeling packages based on features. It promises a lot, and delivers, creating stunning trees that will work well with your 3D engine of choice. It has lots of options and sliders to play with, from LODs to texture reusing and aging, and the geometry reduction method is just fantastic. Still, it's a shame that some interface problems and the pricing scheme prevent it from being the ideal.