- Feb 14, 2012
Model Classification: Hard Surface and Organic
When 3D was still in its infancy, digital modelers were usually put into one of two distinct groups based on the type of meshes they constructed. Although the lines have become blurred, these groups still exist today and play a role in how modelers define themselves in the industry. Also, the distinction of the types of meshes a modeler creates makes it easier for studios looking for talent to find the right digital modeler for their specific modeling needs.
Every 3D mesh can be grouped or classified as either a hard surface or organic. What’s the difference? What defines an object as hard surface? What defines an object as organic? So many objects nowadays seem to blur the lines between the two. How would you make a distinction between these classifications?
What may come as a surprise is that if you ask 20 professional digital modelers what the difference between these two classifications is, you’ll receive 20 different responses. I did just that before writing this section of the book and was quite surprised at some of what I heard.
How can something so seemingly clear-cut bring about so many different ways to classify a 3D model? Before coming to a conclusion, let’s explore the most common responses.
Many artists felt that a model would be classified by how it would be used in a production. A static object, such as a stone statue, gas pump, or street sign, would be considered a hard surface object, whereas objects that would deform or animate, such as an animated human character, flag, or animal would fall into the organic category.
The same item could be classified two different ways depending on what the object is called to do for the shot/project. A statue is made of stone and doesn’t usually deform; therefore, it is a hard surface object. But if it becomes a moving statue, as in the world of Harry Potter, it is organic.
Although a gun has moving parts that can be animated, it is still a rigid object, which makes it a hard surface object, unless of course, someone with super human strength comes along and bends (deforms) the barrel—then it becomes organic.
If the mesh is going to deform in some way, it needs to be modeled differently and it should then be classified as an organic object.
Some believed that it was a model’s attributes, or what an object looks like, that defined whether it was hard surface or organic. So if the mesh had flowing “organic” curves where any shape could smoothly transform into any other, like a character, ornate piece of furniture, or a sleek sports car, it was an organic mesh.
Hard surface objects would be defined as meshes typically involving tight edges or simpler shapes joining together with distinct edges, even if the shapes were soft or sleek, like guns, power tools, and retro robots.
Also, if the object’s surface attributes were that of stone, metal, or glass, it would fall into the hard surface category, whereas objects made up of living tissue, like animals, plants, and people, would be considered organic.
One artist defined the two by focusing solely on the modeling aspect. Objects that require a more “organized” topology could be classified as an organic mesh and easily created using “organic” modeling tools and techniques. He believed that organic meshes tend to have more polygons and could benefit from SubDs more than hard surface objects. Hard surface objects don’t require an organized, semi-regular topology and could be created with fewer polygons with less concern about the object’s underlying mesh.
Model Classification Evaluation
Although each of these schools of thought has valid arguments and may work for a particular artist, we simply can’t classify an object based on how it is constructed, will be used in production, or by its appearance. To do that would cause confusion, because every object could find its way into each category.
Take, for example, my dog Jack. He’s a chocolate lab, which is classified as being part of the Canidae family. For the most part, Jack acts like your average dog, wanting to eat, play, and sleep most of the time. He does, however, show attributes of a cat at times, and every now and then he will scratch at the ground after he urinates, like a cat pawing at its litter box. Although this is common in cats, it doesn’t make Jack part of the Felidae family.
Organic modeling goes beyond the fact that the shape of the model is rounded. Many hard surface objects have organic shapes, like cars, cell phones, and robots, whereas organic objects can have rigid shapes like rocks, insects, and crustaceans. Industrial design has moved more towards organic shapes over the years, and the entertainment industry is taking things that were traditionally hard surface, static objects and deforming them in animation—having gas pumps dance in commercials, for example.
Also, modeling something to perform well when animated is just good modeling technique and shouldn’t determine whether something is hard surface or organic. For example, look at a mesh sculpted in ZBrush, or modeling with metaballs or voxels. You can create something very organic, but these modeling techniques will make the model nonconducive to animating. Would that then be considered hard surface modeling? Of course not.
Most modelers don’t limit their tool and technique use based on whether a model is organic or hard surface. Generally, they use good modeling techniques, which include building a model that’ll hold up if deformed, even if it’s not intended to, and apply those same techniques regardless of whether the model is hard surface or organic.
You hear the terms hard surface and organic modeling all the time in the 3D modeling community, and artists are often defined as one or the other. If you make mostly characters meshes, you are an organic modeler. If you make more architectural or mechanical objects, you are a hard surface modeler. I usually describe myself as an organic character modeler, but it is simply not that straightforward, because I create products and vehicles that are defined as hard surface too.
So back to the point: What’s the difference between hard surface and organic models, and how do we define the two? I suppose, essentially, there is no difference at all, and it is a question of semantics. For the purposes of this book (and based on my personal philosophy), I use the following distinction: Characters, creatures, plant life, and more naturalistic environments are organic models, and architectural environments, vehicles, and mechanical products are hard surface. This is very loose as a definition, and as I’ve tried to emphasize, the lines between the two are indeed very blurred.
Hard surface objects are anything man-made or constructed. Architectural structures, vehicles, robots, and anything machined or manufactured could fall into this category. The robots from FunGoPlay’s Grid Iron Gladiators (www.fungoplay.com), shown in Figure 4.16 would fall into the hard surface category.
[Figure 4.16] Although these robots have smooth organic shapes, they still fall into the hard surface category.
Organic models are subjects that naturally exist in nature. This would include humans, animals, plants, trees, rocks, boulders, terrains, clouds, and even lightning bolts. The nonplayer characters that roam the world of FunGoPlay (Figure 4.17 would be considered organic models.
[Figure 4.17] These characters from FunGoPlay would be classified as organic models.