Conceptual Design and Early Studies |
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Getting Site Data and Building the Context |
A project usually starts with a client’s wish, vision, and hopes described during a conversation with the architect. A list of program requirements is compiled, listing the types of spaces the building will have and its rough area. The architect then starts gathering information and data about the site—aerial photos, photos of the site and context, site-survey files with land information, and building footprints and blocks. Using site analysis, program requirements, and creativity, the architect proceeds to study what shape and size building fits best. Variations of the design are studied, analyzed, critiqued, and presented to the client.
Getting site data into the digital model is the first step in moving from loose napkin sketches to a real project. By importing DWG/DGN site information into Revit, you’ll have an underlay from which to work. (For small projects, this can also be a scanned image of a hand-drawn site situation.) CAD drawings with site information usually come with a rich amount of information that needs to be culled. Using the Visibility/Graphic Overrides dialog, you can hide unnecessary layers to make the drawings more legible. Setting the correct scale and orientation of the site relative to the build-ing will be the most critical beginning steps and should be done during the import of the site file. |
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| Scale |
| In the Import dialog, setting the units to Automatic usually works well if the CAD file was drawn at 1:1 inch scale. If the drawing was scaled, you may find that the scale of the imported file is incor-rect, and you need to re-import the file and set the scale units manually to get useful results. |
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| Orientation |
| The next step is to deal with the orientation of the imported site plan. Maps are usually created so that north is always at the top, and that is how site information should be displayed in final docu-ments. When you’re working on developing a site plan, you’ll prefer to work in a way that is most comfortable for you, so the site is oriented parallel to your computer screen—not to true north. |
Orienting a Site Plan to Fit Your Screen
Suppose you’re starting your design study, and you open a site plan view to import the CAD file with thesite. An imported CAD drawing usually comes in its original coordinates’ orientation, with north/southin the vertical axis:
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If you open the view’s properties, you’ll notice that the Orientationparameter indicates Project North:
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By default, the orientation of a view is set to Project North. By changing the Orientation parameter toTrue North and rotating the True North setting, you can work in a comfortably oriented plan relative toyour screen.
In the View Properties change Orientation to True North, and rotate true north using Tools ProjectPosition/Orientation Rotate True North. A rotation control appears in the view. Rotate to an anglebest suited to work on. Note that this does not mean you’ve rotated the project but rather the world.
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This procedure is more than enough if you don’t intend to send information back to the person youreceived the file from. However, if you’re collaborating with a civil engineer and need to send back thebuilding footprint or an early mass study, you need to establish a connection between the two files sothey have the same coordinates. This can be achieved using the Linking method as well as the AcquireCoordinates functionality. |
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| Positioning Imported Files Relative to the Revit Project |
| You can choose to automatically place or manually place an import. With Automatically Place (under the “Positioning" group in the Import dialog) you have the following options: |
Center-to-center aligns the 3D center points of both models.
Origin-to-origin places the world origin of the linked file at the Revit model’s origin point. If the linked model was created far from the origin point, linking with this option may put the linked file far away from the main model |
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| By shared coordinates places a linked file geometry according to the shared coordinate system created between the two files (this is available only if you’re linking files). If no shared coordi-nate file has been created, Revit alerts you. The Shared Coordinates settings can be found in the Tools drop-down menu; you have the following options: |
Acquire Coordinates allows you to take the coordinates of the linked file into the host model. There is no change to the host model’s internal coordinates; however, the host model acquires the true north of the linked model and its Origin setting.
Publish Coordinates allows you to publish the Origin and True North settings to your linked model. Revit understands that there may be other things in your linked file and you may not want this to be a global change to the linked file. An additional dialog appears that gives you the option to name separate locations for each set of coordinates.
Specify Coordinates at a Point allows you to manually key in x, y, and z coordinates relative to the origin point or define where you want your 0,0,0 point to be.
Report Shared Coordinates shows the E/W (east/west) (x), N/S (north/south) (y), and elevation (z) coordinates of any point in the model. |
You can import a CAD file so that it appears in all views, or you can import it in the Current view only. You will find these options under the Import or Link group box. Remember that for topog-raphy files, you should NOT select the “Current View only" option because you will not be able to convert the imported file into topography.
If you forgot this rule, we advise that you delete the import and re-import, making sure that the Current View option is NOT checked. You will most probably not want the Site file to be visible in all other views, so you can turn its visibility on in the other views later. |
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