Using Photofly with Revit and Vasari

So first lest start with what Photofly is: It is basically the merging of point clouds and photogrammetry. What it does is take a set of photographs of a building and stitches them together in 3D space and figures out the camera locations for each image. Once it does that, it can be used to create a 3D model of the building that is usually accurate enough for basic conceptual design and analysis related to sustainability and engineering. The heavy processing for all of this is done in the cloud and what you install is a small application to view and edit the results of Photofly. You can output the results to a number of file formats that could then be imported into AutoCAD, Revit, Vasari, 3ds Max among others.

I have been playing with the technology preview of Photofly that was presented at AU 2010 and wanted to share some of my findings with you. The Labs team has an update to what is currently available on Labs planned, but we don’t publicly share details regarding the labs release schedule or the final feature set. So some of what I talk about may possibly not make it into the labs release. On the other had a number of the features I mention are already in Photofly (and have been improved in the upcoming release) so you can check it out now even before the new version is made available.

What are the basic steps:

1. Photograph the building all the way around or as many sides as you can and measure at least one vertical and one horizontal dimension that is a large percent of the building dimensions(it will probably take about 20 min)
2. Install Photofly, launch the application and submit your photographs for Photofly to process (could take 30 min or more depending on the number of images).
3. Open up the processed model in Photofly Scene Editor and correct and improve the photo alignment by defining manually points that are common across images. (up to 4 hr for an expert)
4. Once you have a final 3D model - define reference lines and or generate a high density point cloud. 
5. Export reference lines as a DWG file or the point clouds as an LAS point cloud file
6. DWG can be brought into Revit or Vasari  and used as reference lines to build a 3D model of the building
7. Point clouds (LAS file) need to be brought into AutoCAD and used to create some reference lines, planes or solids for import into Revit of Vasari. Or you can use San to BIM to bring the point clouds directly into Revit.

What can it be used for?

With the data from Photofly you can build the basic solid volume of your building that is within a foot or so accuracy. Given that you now have the exterior volume of the building you can do things like sun shadow analysis, wind load, etc. You can also start to define the general location of windows and doors so you can perform basic lighting analysis. Finally you can also locate major trees and other objects in the site so you can figure their impact on the analysis types mentioned above.

Let me show you what the process looks like:

• I took 42 images of our Waltham MA office which took about 20 min.

• Some basic guidance on the photos:

 

• I downloaded and launched the Photo Scene Editor and then added the images to a new project. All the details on how to use the Photo Scene Editor can be found on the Photofly Getting Started page. The Handbook is especially helpful.

• I submitted the project for processing in the cloud

• This is what I got back.

  

• As you can see the camera locations (below) are not all correct. I took the photos in a counter clockwise order around the building but Photofly misplaced some of the cameras. This is due to the fact that the 4 sides of the building are similar.

 

• So I needed to unstitch the images that are incorrect and manually restitch them by identifying common points between images - see below.

 

• If you manually match one image on each side of the building that photofly did not get right you will find that the autostitch will work quite well. I had to go in and unstitch about 20 images and then do manual stitching on about  5 of them. After about 1 hour of work (unstitch, manually restitch, submit, repeat as required) this is what I ended up with. (Your mileage will vary. )

 

• After the stitching is all done properly, I started to draw some reference lines along all the edges. I can then use those as references in Revit when I import the DWG file. You can not use reference points in Revit so you do need to define reference lines.

 

• To improve accuracy. Start by using the Edit> Define World Coordinate System. Place reference points at each corner. Then place reference lines and I strongly recommend you use the constraint tool to make sure all the points are in the same plane. The way you do that is when you are in the place reference line command you can right click for a pop up menu that provides the option to constrain. When you are in constraint mode you will see the plane that you are constraint to. You can find all the details for constraints and all the other features in the Photo Scene Editor handbook (PDF).

 
 

• The second way to get data out of Photofly is by generating a point cloud - see below  (This part is quite cool)

 

• Once you have done that you can take the point clouds into AutoCAD for additional processing and to start creating the model using something like the Labs Shape Extraction Tool for AutoCAD. Then import the DWG file into Revit or Vasari
• Or you can take them into Revit using Scan to BIM.
• BTW - I used Google maps to properly locate the building and set the orientation in Revit

The whole thing takes about 4 hr. once I had the hang of Photofly. You should be able to use the model in Revit for a number of basic analysis and visualization needs. Don't use this tool for as-built models but in half a day you can start to get the building shape, location of windows and other openings , etc. Then run some basic analysis.

One Final thought given it is Oscar season. This could be a very interesting way for film location scouts to show the director what potential sites actually look like in 3D rather than just presenting a set of photographs.

Just one more thing - Photofly is fun to use and extremely addictive ... you have been warned!

I am very interested to know if you have tried Photofly out and if you think it is useful based on the info provided above.