How (and Why) You Should Use 3D PDFs

In the world of structural engineering, clear and accurate communication is key. One tool that has gained popularity in recent years is the 3D PDF. In this blog, we explore how 3D PDFs enhance project delivery.

What is a 3D PDF?

A 3D PDF is still a normal PDF (portable document format, or PDF). It’s the same file you receive and open with adobe, Bluebeam, or other PDF viewer. The difference is that a 3D model is embedded in the file. That means details, plans, or elevations are actually a model, not 2D linework. You can click, drag, and rotate to allow you to view the 3D elements just like you would a 3D element in a BIM software. These can be standalone, or incorporated into a formal construction document set. All run from the lightweight PDF software you already use- no need for computer resource intensive BIM software.

An example PDF is attached at the end of this blog.

Why You Should Use 3D PDFs

How often do you hear the phase: “it’s in the BIM file”? Wouldn’t it be nice if the model was right next the detail in question? If you have complex, curved, or multilayered structures, 2D linework just does not do the project justice.

When a BIM file already exists for the project, a 3D object inserted into a PDF is the perfect solution. It can give you a quick visual of how the pieces come together right next to the element in question.

3D PDFs allow for a more realistic representation of the structural elements. This makes it easier for clients and stakeholders to visualize the final product. It can be especially useful for large-scale projects where it may be difficult to understand the design from 2D drawings alone.

How to Use 3D PDFs

The actual usage is easy, and very intuitive. Clicking (or tapping on a touch screen or tablet) and dragging, zooming let you spin around the model. The view window settings let you change rending openings, or set specific views.

There are a lot more options for generating and setting up the model, but as a user it’s a very simple process, that does not require much effort to get useful information out of.

Two methods exist for creating 3D PDF content, all of which require the 3D model to already exist in a BIM software. Using a plug in inside of the BIM software, the file can be directly output to a 3D PDF with no embellishments (IE a model on white space), or the model can be exported as a *.U3D file. The U3D file can then be inserted as an image into an already existing 2D PDF to allow for titleblocks, 2D details and other information.

Collaboration in Design Review

Collaborators can easily annotate and mark up 3D PDFs. This allows for clear communication and feedback between the structural engineer and the client. This can help to avoid confusion and ensure that the final design meets the client’s expectations.

Additionally, its possible to extract the model back out of the PDF, and bring it into a BIM software for use in collaboration.

Construction Documentation

Embedding 3D models in construction documentation enhances the clarity of instructions. Contractors and builders can refer to the 3D PDFs to better understand the design intent, leading to more accurate and efficient construction processes.

All normal PDF features still function as normal. Stamps, digital signatures can still be applied. Review comments can be marked on the 2D content as well as any 3D views set up in the 3D model.

What are the limitations of 3D PDFs

While a useful tool as a quick reference, there are a few downsides that currently limit 3D PDFs to bonus references, and not the entire contract drawing

• Large models with lots of elements will cause your PDF to be slow or freeze your computer. The 3D model that you start with needs to be optimized for a good user experience.
• Its difficult to create notes and labels. Either the text needs to be 3D modeled, or PDF content added after the U3D file is added. The added content is then only viewable in specific windows that are set – and are generally still editable. Reasonable for quick coordination – but not a good option as a sealed set of contract drawings, or to convey critical information.
• While modeled to scale, there is no reasonable way to extract dimensions from inside of a PDF software. For example: These models can clearly show relationships of elements of how beams intersect columns, but not provide the dimensions of any of those elements.

How McClure is Using 3D PDFS

We are currently using 3D PDFs in two ways:

1.    Adding 3D models to plans or coversheets of sealed construction documents to complex buildings – usually curved buildings where 3d model already exists. This helps understand everyone understand these complex geometries in the field, not just the review teams who are reviewing the BIM files

2.   Sending stand alone 3D PDFs of elements for everyone to review and mark up for coordination. This lets everyone quickly participate in the review and design process, including contractors who do not own Revit or Rhino licenses- and additionally allows comments to be added visually on top of the element being commented on

View a 3D PDF

Below is a 3D PDF you can download to get an understanding of how the 3D visualization functions.

Design Assist 3D PDF Sample

If you open the PDF file with Adobe Acrobat Reader, you may need to enable the 3D content then select the model to active it. Click and hold your left mouse button to rotate the model. You can learn more about 3D PDFs and how to navigate them in Acrobat on their website.

Bluebeam Revu offers additional tools to create, navigate, and markup 3D PDFs that work natively by default. McClure is using Bluebeam plugins to create 3D content from Revit and Rhino models.