Tag Archives: Level of Precision

Smarter Modeling & Top Link Settings

In the wake of our office presentation on Solid Element Operations, I have been getting a lot of feed back, questions, comments and suggestions on use of SEO’s and methods of modeling without them.

I want to point out three scenarios that I came across this morning. One is SEO’s done correctly, the other are wrong. These deal specifically with walls, columns and beams and their relationship to the roof elements above.

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Wall perpendicular to roof slope trimmed to roofs with upward extrusion

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Wall parallel to roof slope, extended to ridge height and trimmed with upward extrusion

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Columns extended beyond roof plane and trimmed with upward extrusion

The basic idea here is that elements are all extended beyond the roof and then cleaned up by using SEO’s. This is wrong for several reasons:

  • First, this habit will cause more unnecessary SEO’s in the project. And we have already covered why that is problematic
  • Second, these elements can interact, intersect, create voids in elements above, such as dormer walls
  • Third, these walls do not clean up correctly with their roofs in section, wall section, details
  • Fourth, it runs a risk of saving out incorrect or inaccurate IFC or SKP files

The correct method for making these walls/columns/beams flexible to design adjustments is to set them to the correct height relative to the story above. Top link the wall, even if it is grossly below the story above, as in this case where the floor to roof height is 18′ in the story settings; so the top of wall is -9′ to story above.

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18′ floor to floor height for floor/roof stories

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Wall Top linked to Roof and set at -9′

Precise Modeling is a Must!

Please note the following is riddled with links to helpful sites and articles on this topic:

There have been many articles written about BIM workflow concepts as they relate to Level of Detail. Our own BIM manual home page discusses level of detail in terms of what we model, why we model (vs draft), and most importantly when we model elements.

A more unique concept is level of precision. This has been touched on a handful of times, most notably by James Murray from Rill Architects who wrote an article on Sloppy Modeling. Note the last line of that article, “Precise modeling is essential to Archicad success”. With the exception of office standards for dimension precision (1/64” not ¼”), James’ bullet points can be followed 100% here at WWA. A response to that article was written by Jared Banks of Shoegnome.com. There are some great tips in this article as well; most notably the concept that, at times we may need to work loose and fast, but this should be done in a separate file that will not cause negative implications later on in the main project’s teamwork file.

The big picture is this: whether a project is a pre-design diagram, early schematic design, or design development model, every element should be placed with a level of care which guarantees that the model can continue to be developed without the need for continual clean up and checking dimensions. Even if an exact (final) size is not known for a given element, that element should be modeled to a precise dimension with a precise relationship to its surroundings. This way, when the detail and dimensions become known, the elements can be quickly adjusted or redone without the need to scrutinize every condition.

Model managers should perform regular self audits to check the precision and accuracy of the model. Here is the link to the WWA BIM manual on project audits. Check walls and beams for alignment and orthogonality. Check dimensions for precision, chase out any dimension less than ¼”. Look for a BIM manual post covering Level of Precision at WWA soon.

Cabinet Objects

This week, Grace has been exploring the use of cabinet objects to represent the doors of a cabinet, allowing a single source for changing the door style and configuration, but leaving the cabinet face and box to a more flexible and detailed modeling element.

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Essentially turning the toe kick and counter portions of the cabinet off. This is a great solution for “future proofing the BIM process“, but requires turning those portions off to achieve the required design and appearance.

You can not set these elements to 0′-0”, as the GDL requires a distance for its script. You can turn the countertop off in the counter edge settings:

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Future Proof Your BIM Process

The WWA BIM Manual home page describes Why, What and When we model design elements in BIM in a somewhat vague and conceptual way. Understanding this concept is incredibly critical though, since designs change throughout the various phases of the process.

We can not get away with not showing elements simply because we don’t know exactly what they are. A BIM process is centered around exploring what elements are and developing them in a circular process. We can take a basic idea or concept and explore massing to detailed iterations in a very fluid way; and if done correctly, we can either start over or go to final documentation with little or no time loss.

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The perfect example of this work flow and level of detail is cabinetry. Cabinet and built-in elements are not only dependent on the phase, but also the design for the best way to model them and when to add the details.

A flush panel euro style cabinet may be best modeled using morphs from the onset. A more shaker style cabinet with overlay panels may be best suited for cabinet objects with preset doors or custom door components. An inset frameless cabinet with recessed panels may be best modeled with walls and doors.

cabinet process

designing from Custom Profile to Morph to Object(s) ensures a seamless workflow and options to “back-track” without starting over

The important thing to note is that the IDEA portion (LOD 100: Basic shape/size), should always be modeled as basically as possible. This ensures that we do not need to know what style or type the element is at first to at least represent that the idea exists. The process to final documentation should be as gradual as possible, even if we need to show higher level of detail than the current phase warrants.

In the style/process example illustrated above, a cabinet type and door style could easily be transitioned to any other design, with little extra time spent on redoing model elements.

This is also one reason that objects (GDL based elements) offer more flexibility than massing or modeling with individual elements, such as morphs, slabs, walls, beams, columns. With GDL doors or cabinets for example, the door style can be changed globally by simply overwriting or replacing the door panel on all cabinets.

To change a door panel or cabinet type on a single morph element or collection of slabs, beams and columns, significant time needs to be invested into revisiting each cabinet elevation and making individual changes to each.

Level of Precision, Walls

ARCHICAD 19 has an interesting bug that has developed from [presumably] the introduction of the new reference and snap features. This can occasionally result in a low level of precision, where elements are just slightly off orthogonal.

Graphisofts recommendation on combatting this is to “click carefully”, which works. I have run into some cases where clicking carefully and moving precisely has still resulted in slightly imprecise modeling.

Thankfully James Murray and Link Ellis have developed a label that has helped me combat this issue and track down any model elements (walls and beams) that are off orthogonal, even to the nearest 1000th decimal point!

We now have their label in our library, it is called “Ortho Label Check 19” available in the label settings.Screen Shot 2015-11-20 at 4.45.06 PM

With a single click you can check the angle of any wall or beam in floor plan view and get an “ok” for walls that are modeled correctly or an angle increment for walls that are “slightly off”.

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I ran a check on my entire model and tracked down each wall that was misaligned (only 2), and fixed them. I will be using this for project audits, and encourage others to use it as a self-audit, when you run up against walls that will not heal correctly in elevation/section.

Modeling Wall Ends

As with everything in ARCHICAD, there are several ways (or seemingly infinite ways in some cases) to model any design conditions. When it comes to a wall end wrapped with a finish or trim, there are only a couple of good options. 1) The wall end tool, and 2) a custom profiled column.

Option 1 falls apart in several conditions and for one specific reason. In floor plan, the wall end has lines that you may not want to see, and in RCP (3d Document) the fills and pens do not match. The reason for this is that the walls use building materials, but the wall end tool is a GDL object which uses fills, not building materials. A fill will never clean up with a building material, so option 1 should be considered an unacceptable solution.

This is crap, dont do this!

Option 2 has the advantage of using a building material, cleaning up perfectly with the wall and looking correct in all views. Additionally this option forces the wall length to be modeled correctly to the actual core length, as opposed to the full wall length (face of finish) that is required for the wall end tool to show correctly. The only shortcoming a complex profiled column has is the column does not move with the wall when the wall is extended or shifted; but its a small amount of coordination to ensure the plans, elevations, model, and RCP all show cleanly and correctly.

Thats a nice looking wall end!

BIM Element Wants and Needs

In recent project audits and reviews I noticed a few projects that had disconnected and un-parametric elements and objects to represent very simple model elements. A toilet, for example, with a separate drafted floor plan and 3d/elevation view.

It was explained that this was done to show the manufacturers specific dimensions, shape and style in plan. Although there are ways change or override an objects plan symbol to show exactly what is perceived as necessary, this raises a much bigger question. What really is necessary in a drawing/model element? We may want a plan symbol or elevation of an element to match identically to a manufacturers drawing, but is that really necessary? I would say an exact graphic representation to a manufacturers spec is very low on the priority list for a BIM element, at least in most cases.

The Needs

So what are the priorities for a BIM element? We can assign a hierarchy of what a BIM element should represent to better understand.

  1. A BIM element needs to be parametric with a single element representing all views. Without this criteria being met before all else, the drawings are prone to redundancies and inconsistencies, and we loose almost all efficiencies of a BIM model and BIM process.
  2. A BIM element should match the overall size of the manufacturers specifications. This ensures that critical clearances and space requirements of a specific model element are met. This is overall dimensions; because a basic 3D cube with an associated plan symbol may meet criteria #1 and would be far superior to disconnected 2d plan and elevation views of an element.
  3. A BIM element should be placed in the correct location as its overall dimensions relate to the space it will be installed/built in. It should be in the correct location in plan, elevation and 3d views to show its relationship to all other model elements.

After these criteria are met, an element will be consistent in all views, it will be easily managed, maintained and edited, it will represent the correct size and represent the design intent. Anything else a model element requires is not a project need, but simply a “want” of the designer.

What does this all mean? Simply that in most cases we do not need a manufacturers specific element. Rather we need a generic element that represents the manufacturers size and the designed location of an element.

The toilet, as in the initial example, could be a basic out of the box ARCHICAD toilet that was set to the manufacturers size and placed correctly in plan. This would be enough to convey the design intent and document the building sufficiently.

The Wants

There may be some obvious additions to the hierarchy above, but rarely if ever should these take priority over the needs of a BIM element.

  1. Elements that are not part of the documentation, such as furniture or decoration used for visualization only may not require much thought towards what the plan or elevation views look like, but only need to show a quality 3d view. Elements that are placed only for BIMx or renderings would be a waste of time to build a correct plan symbol and parameters for listing into the element.
  2. Elements that require a manufacturers specific appearance to properly leverage a models visualization to make selections. Appliances and plumbing fixtures may meet this exception, but these elements should also be modeled so that their plan symbol, elevation view and 3d representation may meet the BIM element criteria above.
  3. An element that needs a higher level of accuracy to show relationships to finishes may require additional criteria, but may not ignore the top 3 criteria listed above. For example, a wall mounted faucet may need to show relationship to grout joints. So an additional element criteria would be manufacturers detailed dimensions. For this type of element all other criteria must be met; which means a custom object would need to be built or downloaded to maintain the integrity of the model.