Google Earth + REVIT

The link between Google Earth and REVIT materialized into a Revit Extension available from the Autodesk Subscription Center since 2007. The extension allow to georeference your project with a GE aerial map imported directly into a REVIT view. But how about the GE surfaces?  Hmm...There is currently no direct way to extract GE contours into REVIT, but it IS possible to do this via AutoCAD.

The Google Earth Extension for Autodesk-based products has been available as a technology preview application from the Autodesk Labs website. http://labs.blogs.com/its_alive_in_the_lab/google_earth/

This extension allows users to publish 3D models from AutoCAD directly into Google Earth as .kmz files, import an aerial photo, and/or drape a Google Earth image over and AutoCAD 3D mesh.  The numerous installation files are dependent of both the AutoCAD and the GE version number. After installing the application, for the extension to run properly, load manually via MENULOAD the GoogleEarth.cui  and load via APPLOAD the  AeccDWGToGE.arx, both files residing in the main ACAD support folder location. The .cui will create a small Google Earth for AutoCAD toolbar:

The second tool left-to-right IMPORTGEMESH, (the icon with the blue mesh), will capture the Google Earth surface elevations and will import it into any AutoCAD based product (CAD, ACA, CIVIL & MAP).
The tool will drape a Black & White aerial image over the mesh, visible only when you switch visibility to Realistic. It is important to keep both applications open during the operation, and it is important that the GE view is perpendicular to the earth surface (no tilt).  The tool will always create a 32x32 mesh with elevations relative to the Sea Level 0'-0".

Save the file as a dwg in a subfolder beneath your Revit project folder.  Link the dwg into REVIT and generate a Toposurface using the Imported Instance Method. Place the dwg using the Auto - Origin to Origin option to preserve the elevation info. More important, the key here is to review the contour ranges and settings in the Site Settings before generating the toposurface.

A color aerial map can be drapped over the toposurface as part of an assigned Material.  To do this, save the GE color image as a jpg and associate the image into new generic material using the Material Browser/Material Editor.  Make sure that the size of the material tile matches the actual size of the toposurface, by disabling the tile proportionality lock. See the options below:

The image will display only when the View Style is switched to Realistic.  See the final result:

Retaining Wall Profile at Toposurfaces

It is widly recognized that Revit weakest link is the site grading and the new RAC 2012 still fall short in many of the site modification features, one of them is the ability snap to toposurfaces profiles.

The issue in discussion is as follows.  A pad is built over a toposurface, retaining walls are needed at the the pad perimeters, and the top of the wall shall follows the toposurface profile.  While a section view can reveal the actual surface profile, Revit cannot match it to the top of the wall. Simply said, one cannot snap to a toposurface profile in any sketch mode. This limitation has long been reported in wishlists for years.

Few workarounds exist. One approach, if your budget is generous enough, is to purchase EaglePoint's SiteWorks add-on, which enable this feature for several hundred dollars.  Another approach is to trace-eyeball the wall profile but we know this will not be accurate.  And my suggested approach is as follows:
1)  Create a section looking toward the wall and switch to a wireframe style.

2)  Export the section view as a dwg, using the default options.

3)  Link the CAD back into the section view, making sure it is positioned  "Auto - Origin to Origin" and placed in the "Current View only". The purpose of this is to use the ACAD linked lines as snapping references when modifying the wall profile.

 4) Edit the 'Wall Profile" and using the 'Pick Lines' tool, select the CAD profile lines. This is the accuracy we were looking for!

5) Erase the linked CAD dwg.

While exporting to dwg is a shotfall - the wall will not update should the surface changes-, the result is still precise. Share your thoughts if you have found an alternate method.

Gridline gridlocks untangled

A user in my company asked me how to control the extent of gridlines in multiple views. The ADESK help files are terrible at explaining a fairly simple process, so here is my revisited explanation.
A grid is a vertical plane that defines the location of structural elements. A grid in REVIT is an element composed of two entities: 1) A datum 'plane'  2) A linework that make it visible in projection.  Gridlines are not visible in 3D, only in projection views, such as elevations or sections. The datum plane and its associated linework may or may not have the same extent. How can you tell?

Let's look at these four grid properties:
- A hollow grip indicates the end of the datum plane.
- A small solid blue grip indicates the end of the grid projection linework.
- A 3D symbol indicates that the datum extent is in sync with the linework.
- A 2D symbol indicates that the datum and the projection linework are independent, or have different ends.

Here is the fun part. Clicking over the 3D symbol 'divorce' the datum end from the projection linework, converting the hollow grip into a solid grip. In other words, views can have different projection ends, but the datum end remains unique in the project.

To re-synchronize the datum plane with the projection linework,  rejoin the grips, and the grid will return to a '3D' state.  If the grid end is outside the crop view region, the grids will not be converted.

The grid  right-click menu has additional grid controls:

Drag End:  Moves an end grip end along the grid line. This command only works when you hoover over the solid blue grip and enable the right click mouse menu.
Reset to Crop: Trims or extends the projection linework to the annotation crop boundary. Use this to fix the extent of gridlines modified while the crop region was switched off.
Reset to 3D Extents: Synchronizes the projection line end with the datum end. This is the equivalent of manually dragging the solid grip over the hollow grip
Maximize 3D Extents:  Extends the datum ends to the boundary defined by the farthest geometry in the project.  However, this will NOT work if the view crop region is visible. Switch off the crop region to use this command.

An extremely useful control is the Propagate Extends tool in the grid contextual ribbon. This will replicate the linework of a system of grids from the current view to multiple views. For example, if you worked arduosly to set your grid linework in a certain way, ie displaying custom arm and leg breaks, you can copy the same display properties across several views.  Don't re-dothis view by view. This is precious time wasted!

Lastly... you can associate a grid line with a scope box per family instance properties. This does two things: 1) It will lock the datum extent (hollow grip) to the scope box boundary and 2) it will place the linework end (solid blue grip) at a fixed 1" distance from the scope box boundary.  Use scope boxes to apply a consistent grid display in multiple views with different plan orientations, ie enlarged detail plans. Where does the 1" come from? hmm..."sepajudas" like we say in spanish.  Post a comment to me if you know the answer!

Toposurface Profiles

Any section thru a toposurface will display its profile, but the profile lines in a view cannot be used as snapping references, nor can they be extracted as detail or model lines.  This has been an unfortunate known limitation... until now.   The 'surface tool triangulation' posted by Anthony in the AUGI forum allow the creation of model lines that follow a toposurface profile based on the location of a pad and a wall.  This add-on can be downloaded here, and works like a charm:
http://forums.augi.com/showthread.php?p=1089399#post1089399

The advantages are multiple. You can convert the profile lines into detail lines, utilize the profile to trace the top of a retaining wall, offset the profile to define an vertical easement, and or export just the profile lines to other CAD\CIVIL applications.

Introductory Post

Hello, welcome to my blog! It has been on my mind for quite some time to create a technical space documenting my periodic musings on Building Information Modeling. A few times a month as time allows I’ll try to intermix thoughts on key issues and whatever else might provoke a conversation about REVIT. 

Cheers