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In a World Focused on 3D Working, Why Is There Still a Demand for 2D?

Updated: Jan 31

In an industry that is constantly evolving and looking towards the newest methods of working, it can come as a surprise that although there is a will to move forward there isn’t always the way. SUMO’s Tony Rogers explains why although we are seeing an increasing shift towards full 3D outputs, we are regularly asked for traditional 2D deliverables.

2D plans and elevations at St Albans Cathedral

Above: 2D plans and elevations at St Albans Cathedral created by APR Services

So, Tony, what is your initial reaction to the continued work in 2D as opposed to shifting fully to 3D?

In our experience, our clients tell us that the use of 3D is generally only beneficial at the design stage of a project. Design professionals such as architects will often benefit by working in 3D. Although, most other trades within the building process continue to work in 2D. So with this mixture of client needs, I am not sure there will ever be a full shift to 3D.

In fact, 2D drawings are actually required throughout the entire build process by many trade professionals. Although it is possible to extract basic 2D drawings from 3D models, this process tends to need further manipulation.

The use of 3D can be inappropriate for many projects and environments due to the following factors:

  • 3D costs more to work with. It often requires a higher level of skill and more expensive equipment to interpret.

  • Creating work in 3D can generate an unnecessary level of detail. Meaning that you have a very complex and data hungry data set which is not needed.

You mentioned that 3D can be inappropriate for certain projects and environments. Can you tell us more?

Yes, the obvious area where this point is most true is Heritage work. Usually in Heritage projects, features aren’t square or regular. We find that everything is individual and needs to be drawn independently. Modelling in 3D to this level of detail for such projects is difficult as well as having the potential to be very expensive. That said, we can still capture the intricate details via 3D laser scanning. Then we generate the 2D output as discussed further below.

An example of a project such as this is St Albans Cathedral. APR Services (now part of the SUMO Group) have been surveying this site in stages for the last 15 years. The initial data captured using 3D laser scanning. We then used the scan data to provide detailed plans and elevations (often down to individual bricks) in 2D to meet the needs of the Conservation Architects.

2D survey deliverable from St Albans Cathedral.

Above: A section of the 2D survey deliverable from St Albans Cathedral.

St Albans Cathedral

Above: This photograph of the St Albans Cathedral shows the external appearance of the building. In the final survey drawing, the bricks have been individually drawn for the highest-degree of accuracy.

The walls of St Albans Cathedral are not straight. As well as this, other features are irregular and the floors are not level. 3D models would not be appropriate or useful as there too many irregularities within the building. This is generally expected from a building of this age.

So, what are the main challenges with 3D modelling Heritage sites?

3D software, such as Revit, is designed for creating new buildings and structures from scratch in a virtual environment. Whereas the sites that SUMO survey exist within the ‘real world’ and have to be portrayed in a CAD environment. 3D software (often ideal for the design stages) lacks the tools to measure the level of irregularity found on heritage structures.

What deliverables do SUMO generally produce as requested by clients?

In recent years, the wider use of Laser Scanners allows surveyors to capture everything easily in 3D in one mobilisation. This cuts the need for more visits to capture extra data. It also gives us the option to offer clients this data as a 2D and/or 3D deliverable. We can capture the finest details as a ‘cloud of points’ using the laser scanner. However, converting this point cloud data to 3D solid objects is not an easy task. This is because Meshes used during the modelling process are very heavy to manipulate. As well as this direct modelling is complex and time-consuming. Often we create 2D drawings or what we call ‘ortho images’ of complex features as this is all that is required for the work to carry on.

We can also provide the point cloud for clients to then model from themselves. This is becoming more common as clients can decide the tolerance they will model to, rather than the surveyor.

In addition, whilst 3D views make it easy to see how something looks, you cannot physically measure or manipulate them without specialist tools.

Can you give us a summary of why surveyors are still experiencing larger volumes of 2D requests?

The majority of clients request 2D drawings as they are still working or designing in 2D. This is often the case, particularly on the smaller projects. It is a slow transition to 3D. I believe advances in the software are still needed before it is going to become the ‘norm’. There is a need for skill advancements, as it’s not an easy task for many of the people using the information to be able to manipulate 3D models. We have been using 2D drawings for many centuries. So it is not surprising that it will be a while yet before we are all willing and able to give up the medium.

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