The Building Coder

FindReferencesByDirection

This is part 9 of Scott Conover's AU 2009 class on analysing building geometry, dealing with the FindReferencesByDirection method and its use as an applications 'eyes'. We mentioned the method briefly in our discussions on how to find a host or a foundation element, Harry Mattison recently presented a very compelling example using it to simulate a pool table in a Revit model, and Scott himself provided the real-world example for creating spot elevations on the top surface of a... Read more →

Spot Elevation Creation on Top of Beam

Here is another interesting solution to discuss in between the series on the Revit API geometry library from Scott Conover's Autodesk University presentation on analysing building geometry. This issue was also raised by Scott and deals with adding a spot elevation to a beam. It contains useful information both about spot elevation creation and using FindReferencesByDirection to find the top of a beam more easily than with get_Geometry. Question: I am trying to add a spot dimension to the location... Read more →

Project Location

This is part 8 of Scott Conover's AU 2009 class on analysing building geometry, dealing with the project location and its effect on element transformations. We aready looked at the project location in the discussion on unrotate north. However, as Scott pointed out, the results presented there are somewhat misleading and are subsumed by the following discussion. The project location obviously also affects the azimuth of an element, i.e. the angle between the element and true north, and our previous... Read more →

Extra Transaction Required

Here is another interesting issue to discuss in between the series of instalments of background information on the Revit API geometry library from Scott's Autodesk University presentation on analysing building geometry. As we mentioned repeatedly in the past, Revit automatically opens a transaction when an external command is invoked, and closes or aborts it when the command terminates, depending on the command result returned by the Execute method. This affects the document IsModified property and clarifies why you need to... Read more →

Transformations

This is part 7 of Scott Conover's AU 2009 class on analysing building geometry, exploring coordinate transformations and the placement and orientation of family instances. For completeness sake, here are some back pointers to previous blog posts dealing with transforms and related issues: The Transform class. Polygon transformation. Instance coordinate transformation. Transforming an element. Scaling a curve. So now I hand the word back to Scott: Coordinate Transformations Revit and the Revit API use coordinate transformations in a variety of... Read more →

Insert Face-Hosted Sprinkler

In between the series of background information from Scott's Autodesk University presentation on analysing building geometry, let's have a look at another example that combines a little bit of geometric analysis with other issues. This example is from a case handled by Joe Ye and exploring how to insert a face-hosted sprinkler into the model. A family instance is used to represent the sprinkler, so we presumably need to make use of one of the overloads of the NewFamilyInstance method.... Read more →

Face Edges

This is part 6 of Scott Conover's AU 2009 class on analysing building geometry. Edge and Face Parameterization Edges are boundary curves for a given face. Iterate the edges of a Face using the EdgeLoops property. Each loop represents one closed boundary on the face. Edges are always parameterized from 0 to 1. An edge is usually defined by computing intersection of two faces. But Revit doesn't recompute this intersection when it draws graphics. So the edge stores a list... Read more →

Retrieving Project Parameters

In between the series of background information from Scott's Autodesk University presentation on analysing building geometry, let's have a quick look at a completely different question, on retrieving all shared parameters from a Revit project. Other posts related to shared parameters are listed at the end of our discussion of RDBLink Export. The following solution comes from a case handled by Saikat Bhattacharya. Question: How can I programmatically retrieve the set of project parameters added to a given Revit project?... Read more →

Faces

This is part 5 of Scott Conover's AU 2009 class on analysing building geometry. Faces in the Revit API can be described as mathematical functions of two input parameters 'u' and 'v', where the location of the face at any given point in XYZ space is a function of the parameters. The U and V directions are automatically determined based on the shape of the given face. Lines of constant U or V can be represented as gridlines on the... Read more →

Rectangular Duct Corners

In between the series of background information from Scott's Autodesk University presentation on analysing building geometry, let's have a quick look at a practical application. This is an MEP-specific issue on how to determine the corners of a rectangular duct. One approach to determine this information is to perform the following steps: Analyse the duct geometry. Extract its solid. Iterate over the faces. Select the face containing the rectangular connector. Determine its four corners. We explored the geometry of various... Read more →

DevLabs and Training

Kean just pointed out that we have scheduled a number of new DevLabs for this year. Two of them, in Munich and Beijing, will be offering support for Revit developers. We have also updated the API training schedule (which you can also access from the easy-to-remember URL autodesk.com/apitraining). It includes some class room trainings on the Revit API. We are thinking of holding some webcasts on various aspects of the Revit API as well, and will add them to the... Read more →

Curves

This is part 4 of Scott Conover's AU 2009 class on analysing building geometry. Curve Types Revit uses a variety of curve types to represent curve geometry in a document. The curve types and corresponding Revit API classes include: Bounded line – Line Unbound line – Line Arc – Arc Circle – Arc Elliptical arc – Ellipse Ellipse – Ellipse NURBS – NurbSpline Hermite – HermiteSpline Here are the definitions and some notes on each of these curve types: Bounded... Read more →

Model and Detail Curve Colour

We have had several questions on how to change the colour of model or detail curves. Here is an answer to this question from a recent case handled by Joe: Question: I am drawing a detail arc using the Revit API DetailArc class and trying to change its properties like colour, graphic style etc. How can this be achieved? Answer: You can change the detail arc line colour by changing the colour of the detail curve category's line style. Here... Read more →

South Facing Walls

This is part 3 of Scott Conover's AU 2009 class on analysing building geometry, demonstrating how to find and highlight south facing exterior walls. The previous post discussed curve parametrisation. In this step, we use the tangent vector to the wall location curve to find all exterior walls in the model facing south: The code we discuss is for demonstration purposes on how to use the curve properties. This sample demonstrates the analysis required to determine the facing direction of... Read more →

Import LandXML Surface

Someone recently asked for an API within Revit for handling LandXML data. There is no API for LandXML, but there is nothing to stop us from using standard XML parsing to read LandXML files and use the standard Revit API to generate terrain and other objects. Here is a solution provided by Emmanuel Weyermann of Autodesk demonstrating how to parse a LandXML file and generate a topography surface in the Revit database from its data. I added it as a... Read more →

Curve Parameterisation

This is part 2 of Scott Conover's AU 2009 class on analysing building geometry. Curves in the Revit API can be described as mathematical functions of an input parameter 'u', where the location of the curve at any given point in XYZ space is a function of 'u'. In Revit, the parameter can be represented in two ways: A 'normalized' parameter. The start value of the parameter is 0.0, and the end value is 1.0. This makes evaluation of the... Read more →

Geometry Options

This is part 1 of Scott Conover's AU 2009 class on analysing building geometry. It all starts with the get_Geometry and its options. What are these options? Geometry is typically extracted from the indexed property Element.Geometry, or Element.get_Geometry in C#. This property accepts an options class which you must supply. The options class customizes the type of output you receive: ComputeReferences – this flag sets Revit to make the GeometryObject.Reference property active for each geometry object extracted. When this is... Read more →

gbXML Webcast

Autodesk and the Green Building XML (gbXML) Advisory Board invites you to attend a free webcast titled "Using Green Building XML (gbXML) for Sustainable Building Design - Part II" on January 21, 2010 at 10:00 to 11:00 am PST. Presented by gbXML stakeholders, this webcast will demonstrate how tools for Building Information Modeling (BIM) can integrate with various analyses software, using the interoperability of gbXML to help create more sustainable building designs. Presentations and product demos will include the following:... Read more →

Custom Ribbon Tab Context Switch

Guy Robinson updated his custom ribbon tab solution to correctly handle context switching between standard projects and families. Read more →

Analyse Building Geometry

In a loose series of upcoming posts, I plan to present the content of Scott Conover's brilliant class held at Autodesk University 2009: CP222-3 Analyze Geometry of Buildings Using the Autodesk Revit API. As stated in the class summary, it provides tips and techniques to extract geometric and measurement data from Revit models using the Revit API and teaches how Revit parameterizes 2D and 3D geometry of various building elements, including walls, floors, roofs and structural framing, including techniques for... Read more →

Happy New Year 2010

I am back again from the break. I wish all readers a happy and harmonious new year! I completed the ten day Vipassana course organised by www.dhamma.org, an organisation initiated by S. N. Goenka, which I mentioned before Christmas. Here is a good introductory article describing the goals and the technique. I can highly recommend this retreat to anyone interested in meditation and with ten days to spare, the investment in time is well worthwhile. Beside the goals of seeing... Read more →