Tag Archives: laser

Point Cloud Scan of Column Base using Photographs / Photogrammetry

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

Federal Triangle

USC/CW/ICC Modernization 1994

The Arthur Mellon Auditorium (ICC Building) 1994

Here is a composite drawing of the first really huge (HUGE) building that i used photogrammetry to measure and draw back in 1994.  This work was completed with Ben Frombgen at IAT when we were based in New Haven, CT. We did a complete set of elevations, eleven building profiles (that were later turned into building sections by our client, RTKL) plus a window schedule. It hurts for me to remember how little we charged for this work!  But it was one of our first big commissions and it seemed like a lot at the time.

This is also the first project on which I used a laser measuring device.  If I recall correctly, we were asked to deliver this project in metric units.  I remember being thrilled that the Leica Disto that we bought back then (which was as big as a large box of spaghetti) could switch between units.

I remember also that we had access to a great set of San Francisco based architect Arthur Brown Jr.’s original design drawings (from the 30’s) that were just stunningly beautiful and provided such a contrast to the general level of quality in CAD drafting at the time. Not only was the quality of drafting so great (a beautiful hierarchy of line weights, crisp fluid clarity of description) but the organization of the drawing set was so intelligent and efficient.  We resolved to find a way to draw as well with a computer and have been trying to do so since!

Arthur Brown Jr. also designed the san Francisco City Hall and Coit Tower.

IAT and creating measured drawings of really large buildings

iat-ICC_01After returning to the United States in 1992, I started a company with my friend and fellow architect, Ben Frombgen. We were based in New Haven, CT, and the company was called Innovative Architectural Technologies (IAT).  I am nearly certain that we were the first photogrammetric service bureau in the nation.

This was a challenge.  At the time, out-sourcing was not very common among architects.  A lot of architects were yet to start taking advantage of computer aided drafting software (CAD).  And we were complete novices at running a business!  One of our first big breaks at the time was landing a job with RTKL to do measured drawings of one of the buildings located in the federal triangle.  It was a huge project and we delivered everything on time.  The drawings were detailed enough to provide a unit by unit survey of this magnificent stone structure.  I remember that we had to do everything in metric units and that this requirement was what pushed us to buy our first laser.  It was a Leica Disto, which could provide accurate measurments in english or metric units. Back then the Disto was about the size of box of spaghetti.  I’m now on my third or fourth Disto; they keep getting smaller and more powerful.

Hand-held Laser Measuring device

Hand-held Laser Measuring device