Parametric modeling and direct modeling are two key pillars of designing, in architecture. An architect chooses a type of modeling depending on her requirements, design approach, and external partners. Each construction project requires the alignment of all participants with respect to schedule, design, budget, and even the software. The debate between parametric and direct modeling in architecture is age-old. However, owing to advances in technology, and a shift toward lean & modern architectural practices, revisiting these considerations, is often recommended. Let us look at the two, in-depth.
It was in the year 1987 when history-based modeling was introduced to CAD design. This was the start of parametric modeling. Parameters, which are a set of fields and constraints, are used to create digital models. In this, the modification of the value of a dimension, for example, changes the shape of the object. It is comparable to coding, wherein a minor change in a previous code leads to a completely different output. Also, an error translates into a domino error effect on the rest of the code. For example, the window height can be linked to the height of the wall. Once we change the wall height, the window height adjusts itself automatically. Meaning, the designer does not need to do it manually. Some popular parametric modeling software are Rhino, Revit, Infurnia, and BricsCAD.
Direct modeling however is simpler. Also, known as non-parametric modeling, it allows modeling via direct 3D models. Direct modeling is intuitive, allowing speedy and easy geometric changes. As the name suggests, additions and changes do not depend on previous parameters. A user can learn direct modeling software quickly and achieve results. Owing to the clear edge that it has over history-based modeling in terms of speed and faster modeling, many architects and designers are incorporating a few direct modeling software into their suite. SketchUp, Tinkercad, and Shapr3D are some direct modeling applications that have created a place for themselves owing to specialized features and intuitive interfaces.
In the case of parametric design, models from sketches are created using parameter specifications and modeling commands. Basically, the user must create relationships between the intermediate sketches and the final body, which are mathematical in nature. In parametric modeling, multiple parameters can be simultaneously adjusted with a minor change. And such changes will reflect in any future relationship. New users or users who take on the project at a later stage, need to be adept at understanding all underlying parametric relationships.
In direct modeling, there are no modeling features or commands. Nor does a user create complex geometric relationships between parameters. A user can remove or add geometric details directly. Such changes are quick, easy, and intuitive. Now let us look at the advantages and disadvantages of each.
- The system allows for automatic updating of design, i.e. the user need not make changes in every feature. A change in one translates to changes in all other design parameters.
- Parametric modeling is crucial in functional design as it is a power-packed tool for resolving issues that are structural, visual, material, and perceptive in nature. There is no room for errors in certain aspects of architecture. Such tools give the user the confidence of an error-free design.
- Parametric modeling is important in managing complexity. A well-trained and experienced user can use the intricacies of parametric modeling in architecture to produce designs that are inventive. It gives them a wider canvas to play with, and come up with original ideas.
- Parametric modeling paired with BIM capabilities make for a powerful software suite, that should be in every architect’s arsenal.
- The difficulty of use is a major disadvantage of parametric modeling software. It requires knowledge and experience. A user requires years to master the system.
- Parametric modeling is time-consuming. In the early stages of design, where there are many iterations and only broad-stroke ideas are required, this type of software hampers the speed and agility of work. Further, changes take much longer than direct modeling.
- Direct modeling empowers the user to create powerful designs in 3D, without having the expert skillset to create complex parameters.
- Such software allows users to make changes to designs in an easy and quick manner. The flexibility helps designers go bold with their vision and create breakthrough homes.
- Direct modeling software is packed with features and in-built design elements, which architects & designers can use to enrich their work. Most hands-on designers find it easier to use such libraries to present their ideas to clients quickly; moving later to parametric software where the fine-tuning can take place.
- Cross-team synergies come easy with direct modeling. As such software is easy to use, adaptability is easy. Typically, for building projects; the engineering, architecture, construction, and design teams come from different offices or companies. In such cases, direct modeling software is easier to adopt, so that all teams are on the same page. In the case of parametric modeling software, this isn’t possible given their inherent difficulty of use.
- Working with constraints is probably the biggest drawback of direct modeling. Users must fit their designs within the tools and templates of the software, impeding creative freedom. Owing to the reduced complexity of direct modeling, the number of features is compromised.
- There is little automation in design so changes may not directly be updated. Users need to manually ensure that all aspects of the design have incorporated the changes made at every phase
- Certain free or light versions of direct modeling software may have a weak editing feature. While sufficient for interiors, they might not be great for architecture and construction.
Considering all the above, it makes one wonder, which is then a better approach to modeling? As expected, in this field, there is no right answer. However, a trend that is being observed is architects adopting both kinds of software into their practice. Direct modeling is used in the early stages of a project or for ad hoc requirements during construction. Parametric modeling is used for detailed design. Another trend is the growth of software which provides both kinds of modeling. For any architect, it then makes sense to familiarize oneself with the various approaches to modeling and adapt that which suits their practice, and which helps them synergize with external partners.