BIM API Explanation Video

Project 2 BIM API

For this project, I wanted to improve my parametric family from project 1. My goals were as follows:

• Place multiple windows in a wall
• Place a facade of my "tube panels" from project1
• Use C# to locate the windows and place curtain wall grid lines accordingly
• Switch panels in front of windows to a "flat tube" geometry to allow someone to look through the window and out of the facade

To achieve this, I first needed to modify my family to be able to switch between a "tube" and "flat tube". Because of the nested families, I needed to manipulate geometry 3 layers deep where the family consists of only 1 tube. To achieve this, I created a YES/NO parameter called "Void" to control which geometry is present. I then modeled both a "tube" and a "flat tube" in the same location and with identical Height and Radius constraints. The "tube" is a simple circle extrusion. The "flat tube" is the same geometry with a mirrored void that removes part of the geometry and has parameters to control the ratio of flat area to transitional area. I used a boolean operation to only allow one geometry to be shown at a time, and linked it the "Void" parameter. When this parameter is checked "yes," the voided tube is shown. 

This void parameter is passed all the the way through the nested families and then displayed as an instance parameter for each curtain wall panel in the project.

Once this was completed, I needed to set up my Revit project. I placed a generic wall with 2 windows in it, and a curtain wall 1' in front of it representing the facade/

I created a set of curtain wall grid lines bordering the windows and dimensioned them in both plan and elevation. I then used API to control the further manipulation of the grid lines. To do this I had to establish all dimensions (8 in plan and 4 in elevation) as variables, retrieve and their values. Then I had to establish the grid lines as variables and use the "Move XYZ" command to manipulate their locations. For vertical grid lines, for example, were Move XYZ( "location of window's left sash - location of grid line", 0, 0) which delivered a value of movement change equal to the difference of the previous location of the window and the new location of the window. This allows me to move the windows in any direction or change their width and height:

Then run the program to relocate the grid lines to their correct location.:

Then all I have left to do is switch ON the voids in the panels in front of windows.

Project 1

BIM Model:

The more I work with the Revit interface, the more the workflow begins to make sense. It is definitely a transition from a CAD based system. In my modeling process, I imported a series of raster images of drawings of Villa Savoye and used them as reference to build my model. Once I set up a logical grid system, it became easier to know where things should be placed (partially because of Le Corbusier’s strict adherence to the grid). 

There were a few areas I ran into trouble and on which I had to spend some extra time. The ramp was something I had not worked with previously, and creating the curved curtain wall system was a bit cumbersome. It also took some time to figure out the best way to model the organic wall forms on the top “rooflines” level.

I had to make a few choices as to what I should spend time creating custom objects for and where I should just use an existing family. I decided the custom window was something that needed to be created, as it is an integral part of the design. I created a family whose length, height and sill height could be adjusted to fit any situation. The two outside lights are a function of the overall length, which allows the component to maintain its proportions as its size is altered. 

I also made an “instance” parameter allowing the window to be listed as open or closed. This is not necessary for a BIM, but could be useful in rendering if you wanted to show possibilities. The opening is a product of the window array, and simply restricts the length over which the array can take place causing an “open” “closed” or “partially open” scenario. I have restricted this by making it an “On/Off” parameter, thus preventing the “partially open” option from appearing which prevents a user from potentially breaking the model by inputting an incorrect length.

Parametric Family:

My parametric family is for the creation of a façade system of metal tubes. They are variable in height, width, and radius, and can take on the dimensions of any size curtain wall panel.

I actually created a pair of families. One is a direct “tube” family with only the above parameters. The second is a blended geometry that allows the tube to flatten out over a specified distance to create “openings” in the façade system.

Each family actually consists of three nested families. The first is the basic geometry which is modeled in a “generic model” template.

The second is an arrayed set of the nested geometry. The first family passes its parameters to the second and the second determines the number of tubes along a given length by maintaining a spacing which is a function of the radius. This family is a “generic model – linear” family which allows us to reference a back plane in the third family.

The third family is a “curtain wall panel” family. By nesting the linear array into a curtain wall panel, we are able to pass the dimensions of an infinite number of curtain wall panel possibilities through both nested families which allows the project level to control the height, radius, spacing, and number of tubes on any given panel. This works for both “tube” and “flat tube” panel types.

 Additionally, the “flat tube” panel type has a parameter called “transition” which allows the designer to control the distance over which the tube goes from round to flattened.

The panels can be arranged in any number of ways in a complex curtain wall system.

Intro.

This is the landing pad for my projects in ARCH 653 - Building Information Modeling in Architecture course - Fall '10.