Category Archives: Level of Precision

File Performance – Self Audits

Projects are routinely audited, or at least reviewed on the BIM Server to maintain a reasonable quality of model performance and accuracy. There are specific areas of the audit that are responsible for file performance. Some of these audit sections are worth paying attention to because they can affect file navigation, others can impact general teamwork performance. In any case, these areas of the audit are worth periodically reviewing, even between formal audits.

The areas that need to be self audited are:

  1. The Library Manager
  2. The Library Loading Report
  3. The “Error” Report
  4. The Drawing Manager
  5. Solid Element Operations
  6. Total Model Polygons
  7. Attributes

Library Manager

The Library Manager needs to be periodically reviewed for organization. A disorganized Embedded Library is difficult to maintain, manage, and review. More than the organization, the contents of the Embedded Library are a critical element to file performance. Because the E/L is part of the file, rather than linked to the file like a BIM Server Library, it directly impacts the overall file size; even if content is not placed in the model. Ideally, .gsm content embedded in the file should be less than 10 MB and images used for surfaces should be less than 1 MB. These should be the targeted max for embedded library content. The more frequently an object or image is going to be used in the model, the smaller the file size should be.

Library Loading Report

The library loading report will appear when first opening/joining a file if there are any library issues. These issues may include missing, duplicate, or substituted library content. It may seem like this is just something to close out of and ignore, but this palette is warning that your model may be suffering from poor performance and accuracy. For more on the Library Loading Report, see this WWABIM post here.

Error Report

The report tab will come up when there is processing error in any non-plan model Viewpoint. Like the library loading report, it may be tempting to ignore this tab, but this report is a warning that your model is suffering from invalid geometries, missing attributes, or other errors that can not be resolved. If there are too many errors in the model, the result can be beach balling, slow send/receive, and slow navigation between Views. To review how to clean up Error Report content, see this WWABIM post here.

Drawing Manager

The Drawing Manager often suffers from missing content. Although missing content here may not slow a file down noticeably, the drawing manager is a good place to review externally linked content such as .dwg & .pdf files that have been dropped onto layouts. The drawing manager is a good place to review the update status of content on layouts, which can speed up layout book navigation. This is also a good management tool for tracking external content’s paths to review linked content file size. Linked drawings with large file size can slow the model significantly, and even more so if large files are embedded in the drawing manager. Always review pdf/dwg file size before embedding in the drawing manager. For more information on the Drawing Manager see WWABIM posts here and here.

Solid Element Operations

Solid element operations have been reviewed in past WWABIM posts here, here, and especially here, as well as in a previous internal DD L&L. In running self audits, any element with more than 100 connections should be reviewed, with any unnecessary targets, operators, or other connections removed.

Total Model Polygons

The most important aspect of a model’s performance is often the number of visible polygons. But even if layer and view settings are carefully managed and reviewed, you may run into situations where the entire model needs to be viewed, or may be accidentally viewed. If there are too many polygons in the model, this may result in an slow file performance, beach balling, file or computer freeze up, or even a file crash. With our current hardware, we should be aiming for no more than 5,000,000 polygons for a standard file.

It may not always be a clear line, since the source of polygons as important a role in file performance as the total polygons. For example, in some basic tests and overall experience, 60,000 polygons from a single mesh can perform worse than 1,000,000 polygons from objects. Also, 3,000,000 polygons from a single library part (object tool) placed several times will perform significantly worse than 3,000,000 polygons from 50 different library parts. In general objects contribute to the most polygons, but GDL also handles polygons significantly better than other tools. Overly complex mesh elements and excessive use of morphs can be a bigger performance issue to a file than objects.

Attributes

Attributes can have a huge impact on file performance, as well as document and output file sizes. A large, complex, custom cut or drafting fill can result in an incredibly large pdf or dwg file; in some cases so much so that the files can not be emailed or, in many cases, even printed/plotted. Additionally, custom profiles can result in poor model performance if not properly applied to the model. Profiles applied to walls should be used sparingly, as the intersection between walls results in excessive polygons and slow model performance. Custom profiles are better applied to beams, instead of walls.

The last part of attributes that should be self audited is the naming and file size of the attributes. If surfaces are using large images, it can slow the file down (see Library Manager above). Beyond the image size, the image naming of surfaces is critical to BIMx output. See the WWABIM article here and here for more information on BIMx surface errors.

The Often Neglected Basic Shapes

I think the Basic Shapes often get ignored. These library parts are great as place holders or substitutes for tedious to model objects, basic element massing, or even final model elements. The grid object is great for register and vent grills and grates, drain screens, ceiling grids, trellis elements and more. Some of the other shapes can be used as object massing, or even a starting place for generating custom objects. Creating curved elements directly with the morph tool is possible, but they typically turn out blocky and faceted looking. Starting with a Cylinder, Cone or Sphere allows you to set the resolution of the curves, then convert to a morph to edit or incorporate with other morph elements.

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Some of the objects in this folder may be useless and tacky (the House Model & Conceptual Tree Model for example), but most of these elements can be a dynamic part of modeling complex model elements or even schedule-able place holders for elements that we may not see in the model; such as hidden appliances and plumbing accessories. I recently used a few of these elements to model an exposed sink trap for a bathroom, and it was much faster than trying to build it with beams and columns or morph elements.

The last thing to consider is that these objects often have settings beyond the obvious. Some have settings for adjusting number of faces, curve resolution, overall and individual dimensions. This allows a polygon prism object to accomplish a wide range of geometries, for massing elements as well as trimming elements as a dedicated operator.

Just keep this little library folder in mind next time you are considering building a new custom object, fixture or accessory.

Advanced Object Placement

OK, that title may be a stretch. Placing an object is as simple as selecting it from the Object Tool Settings (the library folders), and clicking in the view it needs to be placed to. But there are some settings that can make placement a little more precise the first time, limiting or eliminating the need to rotate, move, or resize after placement.

First, you can define the insert point of the element. This is the point the element will be placed to when first dropped into the model.

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Insert Point Set to Rear Center of Object

Once the element settings are correct; for all attributes, size, elevation, information, layer, you can click ok to place the object. But there is one more step you can take to place the element multiple times ad different sizes and/or angles.

The Info Box Palette has a row of buttons that gives further control on how objects are placed.

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Object Geometry Method

Option 1 in the Info Box is a standard placement option that will place in the given rotation in the element settings.

Option 2 allows you to define a unique angle for each instance of the object being placed, when it is being placed.

Option 3 allows you to define a new X,Y dimension for the object graphically on the plan, based on the insertion point. This can work well for cabinet objects, tub, and shower objects or even furniture that needs to fit into a specific space.

Option 4 combines both options 1 and 2 into a three click placement to define rotation and size.

Go ahead and play around with these info box setting, and make sure you are aware of the insert point of the objects element settings before placing!

 

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′

Integrate a Trim Reveal Into Doors/Windows

On occasion you may want to pull the interior finish of a wall away from the trim/frame to show a reveal. In the past we have done this with a beam/column/morph SEO around each opening. Now, thanks to a strange glitch in a project, we can replicate a reveal integrated into the Cadimage door and window settings.

First, in the window/door settings, open up the “All Parameters…” drop down from the top of the Cadimage Window – Settings portion of the selection settings.Screen Shot 2016-04-13 at 10.52.18 AM

Next scroll down until you see a drop down for Composite Skins. You can adjust the offset from outside of frame (Wall Hole size), to the position of the composite skins finish.Screen Shot 2016-04-13 at 10.52.36 AM

Once the trim position and frame dimensions are correct, the result for this example is a trim that is flush with the interior face of wall finish, but with a 1/2″ reveal to the trim width.Screen Shot 2016-04-13 at 10.50.47 AM

A couple of things worth noting on this setting:

  • This is a uniform reveal for all sides/top/bottom of the window or door’s relationship to the wall that it is hosted in
  • This is not measured from the trim position, but from the wall hole, or outside edge of the main frame

Smarter BIM with Labels

Precise Model needs to be documented precisely, with as many “smart BIM solutions” as possible. This means elements that update seamlessly to provide information that is as precise as the model.

Manual text and overwritten dimensions are examples of bad solutions that will make sloppy modeling tell a misleading story. There are rare cases where these are unavoidable, but there is usually a smarter solution.

I have been looking at improving our template with as many smart BIM elements as possible. Today I took a look at labels and annotating RCP’s. The new AC19 label types include a label for annotating the elevation of ceiling slabs. Since our RCP’s are created from 3D documents, this ties the bottom or finish surface of the slab to its home story.Screen Shot 2016-01-25 at 2.32.49 PM

I tested this out in a few projects. We can get this label to graphically appear similar if not identical to our current text over RCP solution. With this label, not only does the annotation link to exactly what is modeled, ensuring precise modeling, but it updates with design changes, making it a smarter BIM solution.

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In the project above, I tested this out and actually found a discrepancy between the intended ceiling height and the actual modeled ceiling height. This is a clear example of the benefit of a smarter solution.

There are limits to this label. It only works on slabs, so vaulted ceilings will still need text for now. It also does not work where a home story includes a split level, as this label can only reference a slabs height to home story or height to project zero.

But if the design has single level floor plans with flat ceilings, this is a smart BIM solution. I will be adding this label to our favorites soon, but it can be used out of the box with a few minor graphic adjustments for prefix/suffix content and pen/fill settings.

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.