more progress

Drawing laid out on six sheets to include exterior and interior elevations, plans and building sections

Progress

Posted here are some snap shots of the Renssaelerville Trinity Church project in progress. You can see from the image to the left that I am drawing elevations of both the building’s  interior and exterior.  To make sure that all of my drawings “agree” with each other I start off by blocking everything out and drawing everything at the same time, in a way. I will go back later and address details and such.

Here is a view of five drawings together, laid out with construction lines to help align all the moving prices into a coherent whole: a plan drawing with north- south- east- and west elevations flipped out to the side.  While the source information is in fact 3-D I find that viewing it simultaneously from different vantage points useful for (relatively) quickly constructing a series of architectural drawings.

Here is a view of the church’s main elevation. This shows a partially complete drawings laid over a rectified image that was shot from a distance with a long lense, so it is optically the faced is already flattened out pretty well with regard to the drawing. In oreder to draw individual portions in detail I will use portions of closer up images that are rectified to a series of planes rather than a single rectification plane.

Here is a side view of the building, the north elevation. This shows a mixture of drawing and rectified imagery. On this side of the building I was able to see the roof tops well enought to rectify them as well as the straight ahead portions of the facade.

Finally, here is another interior view that is comprised of a series of rectified images that are assembled into a whole in a mosaic like fashion. In CAD, each individual rectified image can be turned on or off, or set o be screened at 50% or whatever.  I try to create the drawings files with a simple hierarchy that allows for maximum flexibility by the end user.

All of these are snap shots or “screen captures” from AutoCAD drawings software which integrates the line drawing and raster imagery into a virtual 3-D space.  From this point they can be transformed into wire frame models, solid models, or 2-D architectural drawings, or simple printed and/or exported to other digital formats such as photo shop, or PDF files.

Telescoping Tripod

Using my telescoping tripod in Renssalaerville, NY

Over the summer I started a business venture with a friend doing aerial photography with his 1946 Cessna. I do the photos, he does the flying… Anyway, this experience got me hooked on the possibilities of enhanced points of view.

For a long time I’d thought of the cherry picker (aerial lift/bucket truck, etc.) as my only option and had often worked around the lack of great points of view with creative alternatives when budgets and such would not allow the use of a cherry picker.  But, being hooked as I was, I did more research and realized that a relatively low cost solution was available which could yield surprisingly good results – if you have the guts to put your calibrated camera up in the air on a telescoping tripod.

Even if you purchase a well made tripod with adjustable legs that allow the whole rig to be leveled, and even if you attach guy wires to stabilize everything ( if you have the need plus the manpower), even so, it takes some nerve to put your specially calibrated SLR way up into the air!

Of course its range is nothing compared to a big boom lift, but it can let you see over cars and trucks, and bushes and fences and all sorts of things.  Its just one more trick up your sleeve that can help your work become just a little better.

Andrea Pozzo

2D Descriptions of 3D conditions

What I’m talking about…

Andrea Pozzo says it all with this great drawing.

Technical Elevation Drawings – exterior and interior

Exterior Elevations

Here I am posting a few drawings from a project completed about 18 months ago.  These drawings depict the existing conditions of the Luzerne County Courthouse which is located in Wilkes-Barre, PA. More on the building can be found here.  I prepared these for a team of architects and engineers who were to conduct a survey of these surfaces in preparation for an extensive masonry and stone rehabilitation project.  It is a beautiful building with a grand atrium reaching up through the building.  I also did drawings of this interior space.

Interior Elevations

I am posting these to show that, for all the value of rectified imagery, point clouds, three dimensional models – sometimes the most apt documentation is the relatively “old school” approach of using 2-D drawings to depict 3-D conditions through plan elevation and section.  In the end, the documents that I have prepared for clients over the years have had to pass this test: Will these drawings help my team to communicate easily together when assessing and discussing the problems and solutions at hand with a given building?  Will these drawings help me to accuractly assess the scope of work involve – and, will I beable to use them to communicate with and direct the contractors in the field who are doing the actual work to the building?

Earlier this week I was giving a presentation to students at the University of Virginia.  I started off showing them work that I did 15 years ago when everything was more or less analog in nature, later showing how fantastic it is now to be able to merge raster and vector data together digitally. And then I thought of these drawings and how deftly drawings can handle such complex forms with precision and efficiency.  As an industry, we are doubtless moving towards wider use of three dimensional modeling and Building Information Modeling (BIM) – yet I admit to having a fondness for the “old school” approach that I cut my teeth on, so to speak.

View of building exterior

View through atrium to dome

Photogrammetry of Ruins

Rosewell Ruins

In 2005 While I was running the digital documentation studio for Frazier Associates I enjoyed working on this challenging project for the Rosewell Foundation.  My task was to create accurate, architectural documentation of the  remaining masonry walls of this once grand house on the York river in Gloucester County, Virginia. You can read more about the house here.

Documenting ruins is a little different than a standing building.  The goal is less about presenting a description of building in its “platonic essence” and more about presenting it as it actually is at this moment in time.  Capturing the way a wall, tower, or chimney is leaning becomes rather important!  To this end, I prepared the building prior to the photo shoot by fixing special targets that could establish a level datum line (using a laser level).

Rosewell Documentation (interior sufaces)

The drawings and photographs produced for this project were used by architects Mesick Cohen Wilson Baker to create a “Blueprint for the Preservation of the Ruins at Rosewell” which consisted of a history, an structural analysis, an archaeological report, and stabilization plan.

Rosewell Documentation (exterior surfaces)

The Roots of Photogrammetry

 

Stereoscopic View of Worlds Fair Paris 1900

The roots of photogrammetry lie in sterescopy, capturing three dimensional views with pairs of images.  This is almost as old as photography itself.  This image I particularly like because it looks like two capital letters “A” – like my last name – and it is in Paris, where I first learned about photogrammetry.

Mosaic Images from multiple view points simultaneously

Maria Mitchell Hybrid Drawing

Above is what I like to call a “hybrid drawing” of the historic Maria Mitchell House located on the island of Nantucket. A hybrid drawing is one of two things, or possible both: It is a photographic image that behaves like a measured drawing (it is scalable and can provide quantifiable data), or it is a measured drawing that is rich in the way a photographic image is (materials, colors, actual as-found existing conditions are depicted photographically).

Line drawing with key to individual rectified images

Above is a view of the line drawing with all of the rectified images that compose the hybrid drawing “frozen”. In other words, in the CAD drawing, these layers of information are turned off and made invisible so as to see just the line-work itself and a series of polygons that correspond to bit map/raster images that are referenced by the drawing.

Below are a series of images showing each individual rectified photographs as it is situated in the context of the drawing.  These added together make the composite image at the top of this post.

Franklin & Marshall Exterior Survey

Old Main at Franklin and Marshall

Last spring I did some work at Franklin and Marshall College in Lancaster, PA.  I prepared a combination of measured drawings in CAD linked  to rectified photographs of the three oldest structures on the campus. These were then used as base documentation for an assessment of the existing conditions of the masonry surfaces across the extent of these buildings’ exterior facades.

The sequence of this work went roughly as follows:  I first shot photos of all of the buildings from points of view available on the ground (using a specially calibrated digital SLR).  Back in my offices in Virginia I used photogrammetric software to “back calculate” the camera stations and to make precise 3-D measurements of points on the three structures.  I used this dimensionally accurate point cloud as a reference to create rectified photographs of the surfaces visible from grade.

F and M Old Main Rear Elevation

Using the point cloud and the rectified photographs I then created measured line drawings of the structures and laid them out onto tabloid size sheets for use in the field.  These were taken by hand up into an aerial lift so that conditions could be noted with a fair degree of accuracy once assessment were made both visually and manually.

tabloid size field sheet with notes

Once the assessment was completed the data recorded on the field sheets was entered in the CAD drawings.  At this point the line drawings in CAD were enriched by a mosaic of rectified photographs visible inside of AutoCAD.  This allows for an accurate transfer of notes from the field to eventual construction documents.  A sketch of an area or region can be transferred to CAD and become dimensionally reliable.  This is a very important step because it provides for an accurate tally of areas to be treated in one way or another.

aerial lift

Since the main structure was rather tall, I also returned to the site to go up in the aerial lift to collect more photographs to further enrich my drawings with better rectified images of areas that were either blocked by vegetation, neighboring buildings, or were too foreshortened to provide good rectified images.

F and M Old Main Rear Elevation with photos

Measured Drawings on Paper

Basilique St Denis: side and end views of double butress & window

Here I have posted a couple of older drawings from the nineties.  Both are scanned images of prints. The first is a sample of the types of drawings that we were making at Innova for the Basilique St. Denis located north of Paris.  We were charged to create drawings that could delineate each individual construction unit so that a stone mason could make a detailed assessment of the conditions of each, record it, and turn the whole set of documents into a work order.  Some stones were to be completely replaced, others scaled back and replaced with a new facing, many were in fine condition etc. etc.

The second image shows a print of a drawing after such an assessment was made for the terra cotta, masonry and stone cladding that compose the Ocean City City Hall in NJ.  A coding system was devised for individual construction units and linked to a data base.   This print was given to me years ago when I was based in New Haven, CT by Michael Henry of Watson Henry Associates.  While it is possible to create such a document digitally in the field with a tablet computer and so forth, I think that this methodology (making detailed drawings to be printed to appropriate scale onto paper) is still valid today.  Many restoration projects are harsh environments and approaching them with a good set of drawings in hand can be indispensable for creating an accurate record of a hands on assessment.

These paper documents also have archival value in a way that digital files do not.  I once was doing a project like this in New York City. By day I was in the field marking up sheets with a four color pen and by night I was entering my info into my lap top in my hotel room.  (This was valuable because I was able to foresee questions and resolve them the following day before returning to Virginia).  Then on a Thursday morning my hard drive did not wake up and had to be sent out for “emergency disc recovery” – a harrowing experience.  But I had my work backed up to the previous Friday so all I really lost was the data entry from my field sheets to my drawings.  I was so happy to have paper in hand to bring back and use the following week while I waited for my lap top to come back from the dead…

Ocean City City Hall - WHA