3D BIM modeling means building a digital model of a building out of intelligent 3D objects - walls, doors, pipes - that carry information as well as shape. From that one model you get plans, sections, quantities and clash checks. To start, pick a BIM tool such as Revit or Archicad, learn it on a small project, and agree what to model, and in how much detail, before you begin.
BIM (Building Information Modeling) is a process that allows teams to create and manage building information. This includes everything from design sketches to construction drawings, and from material quantities to costs.
In recent years BIM has become essential for design and construction professionals, and many governments now require it on public projects. If you're new to 3D BIM modeling, this guide is for you: I'll cover the basics of 3D BIM modeling, the software, and some tips on getting started.
1) What Is 3D BIM Modeling?
BIM modeling is a process used to create a three-dimensional representation of an asset with information.
The virtual model contains intelligent 3D objects instead of just 2D lines, which helps with visualisation, quantities and simulation of design, construction and the other tasks of the building process. A wall knows it's a wall: its type, its materials, its fire rating and the rooms on either side of it.
The model can also be used to simulate parts of the construction process and the finished building, such as traffic flow, material movement and lighting.
You build a 3D BIM model by placing those objects - walls, windows, pumps, pipes and everything in between - usually working in plan on each level, and the software builds the 3D for you. Once the model exists, it gives you the views of the building or structure you need: plans, sections, elevations, perspective views and more!
That's the big difference between a 3D BIM model and a 3D CAD model: a CAD model is mostly shapes, while a BIM model is a database of building elements that also happens to be 3D.
Here's a great example from Arturo's excellent course about Modeling for Parametric Buildings with Revit:
The benefit of 3D BIM models is that they give a more visual and easily understood picture of the construction project than two-dimensional (2D) drawings. They can also produce accurate quantities for cost estimates, feed the construction programme, and support many other uses!
Read here about Zara's favourite model uses: My Top 10 Uses for BIM in Construction Management - Plus Three Bonus BIM Resources!
2) How To Start Your First 3D BIM Modeling Project
How do you start 3D modelling? The 3D model should always come first, before the 2D drawings. But sometimes the easiest way to start learning is to create a model from a digital copy of an existing set of building plans - scanned paper plans will do.
Once you have a digital copy of your plans, you can reference the 2D, trace the walls and add detailed information about the dimensions and materials of each element. This 2D-to-3D process is still sometimes how BIM models are created on real projects, too! It helps pre-construction teams find the issues in an existing 2D plan set on a project that isn't using BIM yet, although it isn't really proper BIM modeling.
Here's a simple order to work in on your first model:
- Pick one tool and learn its basics - most offer free trials and education licences.
- Choose a small, real building, such as your own home or a small extension.
- Set up levels, grids and the project origin before you model anything, so the model sits in the right place for everyone who uses it later.
- Model the main elements as real objects - walls, floors, roofs, doors and windows - using types rather than one-off shapes.
- Generate your plans, sections and schedules from the model, and fix the model (not the drawing) when something looks wrong.
- Export to IFC and look at it in another tool, the way the rest of the project team will see it.
Here is a basic introduction to creating a 3D floor plan using Revit - from the Balkan Architect:
Once your BIM model is complete, you can use it to create additional information such as schedules, quantities, costs and resources. These uses give a more complete view of your construction project and make it easier to spot problems early, so the project is well planned and coordinated from start to finish!
3) What Software Programs Are Used To Create 3D BIM models?
BIM software programs allow architects, engineers and construction professionals to collaborate on a project's design, construction and operation. The most common 3D BIM modeling software are:
- Autodesk Revit - the most widely used, for architecture, structure and MEP (see Revit on Autodesk's site)
- ArchiCAD - popular with architects, and runs on Mac and Windows
- AllPlan - architecture and engineering, strong in Europe
- Vectorworks - architecture, landscape and entertainment design
- Solidworks - mechanical CAD, used for manufactured products and fabrication
- Bricscad - BIM on the familiar DWG format
- Tekla - structural steel and concrete, down to fabrication detail
Each program has its own unique set of features and capabilities, and they all export IFC so the models can be shared. Then there's software that doesn't build the model but works with it: coordination and clash detection tools, common data environments, and BIM management platforms like Plannerly that set out what each model must contain and check it.
If you'd like to compare BIM tools, Jennee has a great list here: My Top 10 Best BIM Software Programs
4) Tips For Creating Accurate And Realistic 3D Models
Any designer or engineer will tell you that accuracy is vital in 3D modelling, yet even the most experienced designers sometimes struggle to create true-to-life models.
One of the most important things to keep in mind is the scope of your model. Ask yourself who will use the BIM model and what for - that tells you the level of detail you need. Do you really need a realistic model of the existing site, or will some basic massing do? The level of accuracy required also depends on your goal. If you're using manufacturers' products, you won't need to be as precise as if you were designing complex systems to be built from your own fabrication-level drawings.
On a real project, that scope is written down for you, element by element: the level of development (LOD) or level of information need each element must reach at each milestone, and who models it. Read up on levels of development (LODs) and the level of information need, watch the free lesson on visualising BIM, LOD and information requirements, or download the free LOD, LOIN and LOA slides (PDF) (opens in a new tab).
Once you've settled the scope and purpose, focus on the details - accuracy is all about getting the small things right. Pay attention early on to the origin point and coordinate system, so you don't have to make big changes later.
Finally, don't be afraid to ask for help! There's no shame in asking someone with more experience; there are so many experts willing to help. The more you work with 3D modeling software, the better you'll become at creating realistic and accurate models.
5) How Does The Coordination Process Work In 3D Modeling, And How Can It Be Improved?
The coordination process in 3D BIM modeling lets different team members work on different parts of the model at the same time, and then combines their work into one federated model. That's usually the job of the BIM coordinator.
It's not without its challenges. One of the biggest is making sure everyone works with the latest version of each model, especially when teams are in different places or working at different times. With a clear BIM Execution Plan (BEP), a solid Common Data Environment (CDE) and model-syncing software, you can solve most of these issues.
Another challenge is conflicts between different team members' work: two people working on the same area of the model can make changes that clash. Some tools let team members see each other's work in real time, which stops many conflicts before they start, and issue trackers such as BIM Track (now Newforma Konekt) and Revizto pin each clash or issue to the model, assign it to a person and follow it until it's fixed.
Better still, avoid the clashes in the first place: agree who models what, and to what level, before modelling starts. These tools and habits make coordination in 3D BIM modeling far more efficient and effective.
6) What Challenges Does 3D BIM Present To The Construction Industry, And How Can These Be Overcome?
The construction industry increasingly turns to 3D BIM to plan and build more efficiently, but it brings challenges that need to be overcome for it to be truly effective:
- Increased complexity: with 3D BIM, more data and more stakeholders are involved, which can be hard for a traditional industry to keep track of.
- Specialised software and hardware: not every firm has the resources to invest, and keeping up with fast-changing technology is hard.
- A learning curve for designers and contractors alike. It takes time to get used to working with 3D models, and even collaborating online!
These challenges can be overcome. By investing in the right software and training, firms can move to 3D BIM and reap the benefits - and 3D BIM modeling services can help you kick-start your implementation.
Summing Up
3D BIM modeling can be an extremely valuable process for architects and construction professionals. It allows for a more efficient, accurate and collaborative design process.
If you're starting out with 3D BIM modeling, I hope my guide has been a useful starting point - remember to start small and build on your successes. With some practice, you can create stunning 3D models that help you visualise your projects months before they're built!
The Plannerly team is here to help, too. Our free Level 1 BIM Management Basics course covers the workflow around the model - planning, scoping and checking - and you'll find more online resources and tutorials in our free training. Start with the lesson on 3D model navigation.
You can also create a free Plannerly account today to agree who models what, to which level and by when, and to check each model against those requirements once it's delivered - no more surprises later down the line.
Keep reading: what is building information modeling technology?, 10 example BIM goals, my top 5 uses of digital twins with BIM, 9 benefits of virtual design and construction (VDC) and 5 incredible benefits of BIM in construction.
I blog for the Five BIM Bloggers series, where every week we share different perspectives on important BIM topics. To hear our views first, join Plannerly free or browse the Plannerly BIM blog.
