What is LOD (Level of Detail) ?

There still seems to be some confusion about what LOD means, and how they should be used. I must say I have difficulty relating what I do and what I need whenever confronted with filling in an LOD table. If they are this difficult why are we using them? Are they really useful, or just a waste of our time?  

HISTORY OF LOD
From what I can gather LOD was developed by Vicosoftware, a software company that produces construction costing software. They saw the advantages of costing straight from a BIM model, but had a problem. How do you tell how accurate, or how definitive, the model elements you are connecting to in the model are?

Traditional methods of costing have a human between what was being measured and the way it was being measured. But automatic take off from the BIM model doesn't.

So they developed the concept they call "Level of Detail". A measure of how definitive an element is in terms of costing it. So LOD 100 meant not very definitive, an area or volume rate is accurate enough, LOD 200 you can assume the number of items in the model is correct, but use an estimate for each, LOD 300 items are identified and actual cost can be used, LOD 400 is a measure what has actually been supplied so can be used to assess payments.

   Sounds very sensible, very precise. But then the AIA (American Institute of Architects) decided that this system would be a good one to apply to all uses of a BIM model, from energy analysis to 5D programming. They sensibly renamed it "Level of Development" because "Level of Detail" could get confused with the amount of information, rather than the decisiveness of the information. Although both still have an acronym of LOD so the two continue get confused (more on that later).

 Others have taken up the concept, and today it has become one of few common BIM concepts that is kind of understood by all  (more on that later).

WHAT EXACTLY IS LEVEL OF DEVELOPMENT
LOD, as in "Level of Development", is a measure of how seriously you take the information represented by a BIM element. It is not necessarily a measure of the amount of information, although obviously there must be enough information to satisfy the LOD level it is at. It is also not a measure of the amount or accuracy of graphical information. The appearance of a BIM element is only one piece of information about that object, and usually the least important. A contractor doesn't need to know what a desk looks like to order it, nor to place it in the building. But they do need to know what the manufacturer and model number is. Others may need to know its dimensions to coordinate with things around it, but they too do not necessarily need to know what it exactly looks like.

Therefore LOD levels for a chair might go:
LOD 100 = there is a chair
LOD 200 = there is a chair that has nominal space requirement of 500x500
LOD 300 = there is a chair with arm rests and wheels
LOD 400 = manufacturer and model number.
LOD 500 = manufacturer and model number, supplier, date purchased

 or in general terms:
LOD 100 = there is a thing
LOD 200 = there is a thing about this size
LOD 300 = there is a thing with these functions and options
LOD 400 = it is this particular thing.
LOD 500 = this particular thing provided by this person on this date.
LOD is also a measure of progress. At LOD 100 there is obviously more work to do to reach LOD 300. In that sense it is like the traditional percentage complete of drawings. Assuming LOD 500 is 100%, then LOD 100 = 20%, LOD 200 = 40%, LOD 300 = 60% etc.

 Except LOD contains more information. It tells you how decisive each element is, not just how complete its representation is on a drawing. It is more useful to know that on a plan the floor is 60% complete (LOD 300), the walls are 50% complete (LOD 250) and the service ducts are 40% complete (LOD 200), rather than the whole drawing is 50% complete (the average of all elements).
Article provided by Antony McPhee:  Antony has been a registered architect since 1986, he has been a project architect on projects ranging from large commercial and cultural developments to house extensions. Developing CAD systems since 1988, involved in BIM since 2001.

What is BIM?

BIM -- Building Information Modeling -- is very much talked about in the building industry, but what is it, what is it useful for, and who should use it?

 

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Ignore BIM & Pay the Price

Union President: 

Written by Sean Higgins

James Boland, the president of the International Union of Bricklayers and Allied Craftworkers (IUBAC), has written a post on builtworlds.com that may resonate with a lot of you. It's titled Union Perspective: Ignoring BIM at Our Peril. He weighs in on an issue that we've all been hearing a lot about these days--the difficulty that traditional craftsmen have when adapting to new technologies.

We are accustomed to hearing about the challenges that surveyors face when adopting 3D scanning technology, so its quite interesting to hear about it from the point of view of another old and venerable profession.

"BIM, a process for designing and building that saves time and cost, improves estimation accuracy, reduces waste and avoids conflicts in the field, is not new to the construction industry," writes Boland. "Yet the masonry trades lag well behind most others — including concrete placement and steel — in developing tools specifically designed to improve trade-specific planning and execution through BIM."

The article argues that if "the masonry trades" fail to adopt BIM properly, they "risk contributing to their own obsolescence."

Why aren't the masonry trades using BIM? Based on conversations I've had at conferences, it seems many people are either too set in their ways to change, or haven't really been shown how a change can be helpful to them. Part of this is our fault as an industry, because we often hype BIM and other processes or technologies as a solution to all the problems a company might have, but don't do a great job educating people with how to apply those technologies properly.

To his credit, Boland entices the masonry trades by listing the benefits of BIM, but doesn't stop there. Sure, he notes that "its 3D visualizations provide a digital representation of the building, from exterior to interior, which makes scheduling, estimating, site planning and record keeping more accurate and user friendly." But after his sales hook, he draws them to the BIM for Masonry Initiative, which promises education for those masonry tradespeople who are interested in learning more.

It's a good model--entice, then educate. It's also a necessary one: Boland says the masonry trades need to get on board with BIM because designers, architects, engineers, contractors, and so on are already using it to "facilitate smoother workflows and collaboration." The masonry trades, he argues, need to get into BIM, and join in the process of collaboration, or they are going to be left behind when the train leaves the station.

On this point, the article quotes David Biggs, P.E., S.E., who is both a teacher and the head of the BIM for Masonry Initiative as saying, "If we don't incorporate BIM technology into the masonry industry, masonry will seem difficult to work with and become uncompetitive. It is no doubt the future of masonry. It's not a choice, but a must."

HVAC construction contractor uses 3-D software for BIM project

PCL Construction’s Denver buildings division recently tried out Autodesk’s new BIM 360 Layout application on an iPad as part of mixed-use construction project.

Officially released in October 2014, the iOS-based BIM 360 Layout app and corresponding BIM 360 Glue Web service combines Topcon’s three-button LN 100 3-D robotic total station that is specially built for interior and exterior HVAC construction layout.

While this might sound like just another office-to-field, BIM-to-field layout connection, officials say the difference is evident with a quick look at the iPad-based application. Developed through a technology alliance between Autodesk and Topcon, the app is 3-D centric — replacing 20-year-old tabular-based field layout practices with a simple, gesture-controlled and highly visual model-based field layout environment and workflow. The app completely eliminates the manual process of prepping and transferring point coordinate details to field data controllers for conducting layout and quality control on the jobsite.

According to Ondrei Poliak, virtual construction manager for PCL’s Denver district, the solution is a major step forward in 3-D and building information modeling adoption to improve construction workflow efficiency and quality.

‘Advancements’
“I’m always on the lookout for new advancements in technology to streamline our existing processes,” he said. “The BIM 360 Layout app is the next evolution in the process, opening the door to multiple improvements in otherwise error-prone manual layout methods.”

PCL first used the app on a mixed-use development project located in Denver’s Cherry Creek neighborhood. The project features two buildings separated by a midblock roadway. One 8-story office building is 80,000 square feet of single- and multitenant office space and the other is 71 condominium residences and over 30,000 square feet of retail space.

For the project, PCL uses Autodesk Navisworks to aggregate and coordinate all trades on the project including the structural, mechanical, electrical and plumbing models. Once coordination was complete, the 3-D clash-free model became the primary fabrication and installation environment for PCL and all subcontractor trades.

Typically, PCL would use Autodesk Point Layout to create points in the model and then transfer the necessary layout points to a total station for field verification to check the location of staked and installed components from the subcontractor trades. With the new BIM 360 Layout app, the model is uploaded with layout points created in Autodesk Point Layout directly from Navisworks (or AutoCAD and Revit) into the BIM 360 Glue Web service, and then synced with the app installed on an iPad.

Officials say it is as simple as setting up the LN-100 with the project coordination system and walking the site using the app as a guide to find the location of hangers and/or sleeves for staking or verification.

The BIM 360 Layout app provides step-by-step instructions using known point and re-section workflows for total station setup. The app includes two-dimensional viewing options and navigation with gesture-based pan-and-zoom controls.

 “With BIM 360 Layout, we have the assurance that we install exactly per the clash-free model. That’s powerful,” Poliak added. “The business advantage of the app is that we can better utilize our in-house surveyors and our field engineers. Our surveyors can focus on the critical and intensive control setups while field engineers take over the day-to-day routine activities such as quality control checks of hangers and sleeves during construction. We’ve saved so much time that we’re already working with our surveyors to expand their technical expertise to other emerging measurement tasks with technologies such as laser scanning.”

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