Bob White Bridge
Measured Drawings of Bridge Exterior
Last summer I was hired by Frazier Associates in Staunton to prepare some as found documentation of the Bob White Covered Bridge in Patrick County, Virginia for preservation work to be conducted through VDOT. I learned yesterday that bridge was washed away in flash flooding! This is horrible to learn; now only seven covered bridges remain statewide, I believe.
I am therefore VERY glad to have a couple hundred photos of the structure suitable for photogrammetric rectification. I did prepare some simple drawings and orthophotography, small versions of which I’ll share here. I’ll also share some video snap shots of the point cloud I created.
I hope to get in touch with anyone who might be interested in rebuilding. If you stumble upon this page and share my interest please contact me!
Measured Drawings of Bridge in Plan
Below is a view of the point cloud using the free viewer distributed by Autodesk: RECAP.
Overview of point cloud
and a few videos of the orthophotography:
Model of addition projected back into photograph
Typically I use photogrammetry to measure and draw existing structures. Recently I’ve started using it also to visualize new structures. The photo above shows an image that was used originally to create a set of measured drawings of an existing house. Once I had those drawings completed I designed a new structure to be built above the foundation of an existing garage. I made a simple 3-D model of the new design and then accurately projected the model back into the photograph. This has been an invaluable tool in getting my client to understand the new design.
More on this new way of working to come…
Aerial view of Ledoux's Royal Saltworks
This set of buildings located in Arcs-et-Senans (Franche-Comte) is incredibly interesting to anyone with an interest in Thomas Jefferson and/or enlightenment age architecture – notably so since it was not only constructed at the time it was built but is restored and available to the public.
Maison du Directeur (2010)
A lot of information on the Royal Saltworks is available both here and here. Ledoux’s influence on Jefferson is well documented and in evidence in most of his projects. On Jefferson’s Academical Village at the University of Virginia, Ledoux is even “quoted” in one pavilion. But the greater feeling one gets when visiting Ledoux’s Royal Saltworks in Arcs-et-Senans (also a UNESCO World Heritage Site) is the unmistakable kindred spirit between these two architects – their mutual conviction that philosophy and architecture share a link greater than building and commerce.
Point Cloud of the Maison Du Directeur
point cloud "elevation" (perspective removed)
a link to a panoramic view from the “Maison du Directeur” (looking outward) can be found here
rectified photo of the Maison du Directeur
As can be seen in the drawing below, the full design was never fully realized. The “gabelle” or salt tax, was rather unpopular during the time of the French Revolution -making the entire idea of an “ideal city” rather remote.
Saline Royale, Claude-Nicolas Ledoux
Posted in architecture, photogrammetry
Tagged 14, architecture, Arcs-et-Senans, Claude, Enlightenment, Franche-Comte, French Revolution, gabelle, Jefferson, Ledoux, Louis XIV, Nicolas, Saline Royale, Saltworks, tax, Thomas, Unesco, World Heritage Site
A pedestrian bridge that connects Staunton’s downtown to Sears Hill and Woodrow Wilson Park has been moved by the city as part of an effort to restore or repair this important piece of urban fabric. (more info and images of the bridge being moved can be found here.) These photographs (among others) serve to document the bridge and its access stair as they were prior to the bridge being moved. They will prove invaluable should the site be affected while the city raises money to replace the bridge.
A selection of photos of the stair
Below is a partial point cloud scan of the access stair. This particular view is looking down onto the bridge without any perspective distortion – in other words a plan view that can serve as the basis for measured drawings!
Plan view of point cloud
Posted in architecture, photogrammetry
Tagged bridge, City, downtown, move, point cloud, preservation, railroad, replace, restore, Sears Hill, Staunton, urban fabric
Here I am posting a composite elevation of a portion of the stone barn at Morven Park in Leesburg, VA.
Composite Elevation with two of the three images faded to 50% opacity
The “elevation” is actually a composite of three images, each rectified to respect the scale of 1:96 (or a quarter inch equals a foot) when printed at 300dpi. The individual images are posted below.
partial elev left qtr scale at 300dpi
partial elev center qtr scale at 300dpi
partial elev right qtr scale at 300dpi
I’ve been too busy to post a lot of little projects that were in the works at the end of the summer. They’ll have to trickle in unless they get displaced by new projects… I’m just happy that there are projects! This post is just to share a screen shot of a point cloud in autocad that shows the exterior of a stone barn. I’ve found that the density of points has a strong correlation to the content of the photos. In this case, we see that the stone surfaces create a very high density while the painted doors and such read almost not at all.
Screen Capture of point cloud derived from photographs of the stone barn at Morven Park, as viewed in Autocad 2011 software.
Angle View of Building
In between wrapping up summer projects and starting some new ones, I wanted to work on my technique with Elcovision’s powerful new module that allows dense point clouds to be extracted from photographs. I chose the “Marquis Building” on Beverley Street in Staunton for fairly obvious reasons. (In fact there it is at the top of this page on my mast head – from was a two dimensional rectification of the entire block)
(Note: I used considerably more photographs than just these three shown here)
Over the summer I did some training in Switzerland on how to use the new software module – but I did not have access to all of my regular equipment. So this test project was the first time I had a chance to enhance my ‘overlap coverage’ by the use of a telescoping tripod.
The point cloud created from the analysis phase is dense enough to provide a quick sort of three dimensional model of the building even without any additional drawing.
In Elcovision – or AutoCAD for that matter – one can “hover” around the point cloud and take snapshots in either perspective or isometric views.
Plan View of Point Cloud
Point Cloud of Staunton Creamery Building
Here I am posting a point cloud scan of a structure much more mundane than the Arc De Triomphe, a square-ish two storey building located not far from my office. This was produced from about 40 photographs and consists of tens of thousands of point measurements that are represented in their true color.
L'Arc de Triomphe - Paris
I shot a series of photos around the Etoile at the center of which stands this grand monument. It is incredible how busy the traffic is here at all hours, both vehicular and pedestrian! Anyway, from this series I was able to generate a point cloud to describe this massive arch at the head of the Champs Elysee. I then scaled the entire affair based on measurements taken from Google Earth.
Point Cloud Scan of Elevation
I also shot the ‘undercarriage’ of the monument to create a point cloud describing the vaulted surfaces there using photogrammetry. The point cloud itself is dense enough to create a sort of drawing. The location of any additional points – or edges etc. – can then be easily (an accurately) queried directly from the photographs.
Photos of the surfaces underneat
Point Cloud of surfaces underneath
Reflected Ceiling Plan of the Arch's central bay (point cloud)
Point Cloud Scan of Column Base
My second sample project using photographs to create dense point clouds to describe a non orthogonal object used a column base from the cathedral de Saint Pierre de Geneve. These stone surfaces proved to be easier to capture than the sleek, reflective brass surfaces o the sculpture in my previous post.
This point cloud was created with a series of a half dozen photographs shot in an arc from left to right around the subject matter. We can see here that in oreder to get all of the surfaces adequately rendered, one needs to also change the height of the camera’s point of view.
As it is, the point cloud consists of over 15,000 points. The points can be imported directly into AutoCAD with their true colors and manipulated there to be transformed into a surface model – or simply as the basis for a measured line drawing. As for accuracy, 75% of the point measurements (which would include virtually all of the measurements describing the subject close at hand) are accurate to less than 1/8″. Half of them are more accurate than 1/16″.
Here is a photograph of the column base, followed by two more views of the point cloud:
Column base at the Cathedral de Saint Pierre de Geneve
Plan View of the Point Cloud
Side View of the Point Cloud