What is LOD anyway?

2018-12-11

By Paul Haines - BIM Manager, CMS Surveyors

If you are in any way involved in BIM modelling or architectural output, you have come across the acronym LOD. But what is LOD and how does it affect what you do? The answer is a bit confusing so CMS Surveyors have set about making things a bit easier.

The first perplexity to note is that LOD stands for two different but similar concepts. The first is “Level of Development” and the second is “Level of Detail”, with the second being a part of the first and both being similar but not mutually exclusive. Confused yet?

In the world of BIM, Level of Development is the more widely accepted norm for LOD. The American Institute of Architects defined Level of Development as “…(LOD) describes the completeness to which a Model element is developed”, and basically that is the case – it is the amount of detail and information in your model.

The second version of LOD being Level of Detail usually refers to the graphic level of detail included in a model. The difference between the two LODs and how confusing that can become is described in Natspec’s BIM Paper of November 2013 with the diagram below…

 

 

So while Level of Development seeks to provide a sliding scale of “completeness” of a model, it may not make sense for your particular needs. The Natspec paper also sagely notes “…LOD is a means to an end. LOD is meaningless without clear definition of the model’s purpose or intended uses.”

I couldn’t agree more, which is why at CMS Surveyors we have developed a Level of Detail concept to simplify the needs of the architect or designer and provide a clear, structured but still flexible LOD system.

Am I comparing apples with apples?

When you receive a scope of works or issue one for quotes and include a reference to LOD, do you know what you will be receiving? Currently in Australia there is no Australian Standard or industry standard defining LOD, so when you ask for LOD3, what does that look like? And how do you know your quotes will provide the same output?

CMS has spent over 18 months researching existing LOD concepts and developing our own system. We have done this to benefit our clients and provide the following advantages;

  • A clear and concise graphical representation of the proposed output.
  • Provide a system that gives the same level of survey accurate precision in all LODs, rather than other LOD concepts which seek to increase precision as LOD levels rise.
  • A simple system to cut through the confusion of LOD and make a single source of comparison.
  • A sliding scale of detail to models that best suits our client’s needs. Our emphasis is on accuracy and value for money.
  • A bespoke service to provide varying LODs if required to give details where they are needed but not where the details are not as important.

The end result is a simple, succinct method of selection to best suit your needs.

 

 

So how do I get the best value for money?

Architects and designers need to consider not just the lump sum amount of the quote but the true value for money of the service throughout the life of the project. Often the best value is derived from building a relationship based on the trust that an accurate and reliable model will be delivered time after time. The value to you and your client that you have an accurate depiction of the existing building proves its own worth as the project timeline progresses and you know your design is built on trustworthy survey data.

We have previously discussed the “MacLeamy Curve” which represents the differences between a traditional project timeframe whereby the design and modelling is a slow but exponential growth of data and documentation which is exposed to the dangers of high cost and high risk due to inevitable design changes after the tender stage and during construction, versus a model which provides the vast majority of data and modelling at an early stage to allow more resources into the design development stage.

 

 

Furthermore the advantages to having survey data collected by a high definition laser scanner with a 3D position accuracy of 3mm at a range of 50m speaks for itself. The principle we arrive at is that survey accurate data early in the project will save you time and money and eliminate the risk of costly changes during construction.

Take advantage of our Free LOD service

Do you have a Request for Quotes or Scope of Works that requires a level of scanning and modelling output? CMS can provide you with a detailed and bespoke scope of works to include with your documentation to ensure you receive consistent and accurate pricing with no obligation and no cost to you.

We can also provide you with an interactive scope of works document to use to select your required LOD and other survey needs. This enables us to provide you with the most appropriate and best value proposal. For further information, call us on 02 9971 4802 .