3D modeling, History, Montgomery Block
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Building a Window Into The Past

Photo William S. Ricco

Outside the second floor northwest corner office of OP Stidger, 1958

In my search to understand what it felt like to walk the halls and offices of the Montgomery Block, just having architectural drawings — even very detailed ones — wouldn’t be sufficient. Luckily, the Historic American Buildings Survey of the Montgomery Block contains a handful of black-and-white reference photographs of both interior and exterior views. The photograph above was a crucial document for confirming wall thicknesses, general construction quality, and condition of the building. It was also a perfect test subject for my 3D model of the building.  If everything shown in the photograph aligned with the corresponding feature in my model, then I would know for sure that my model was right.

The first step in building my own Montgomery Block was to follow the instructions for building the subcomponents. Doors, chair rails, stairs, and windows all had been meticulously measured and recorded, and all I needed to do was to transfer those measurements into the digital world, then copy and paste them throughout, according to the floor plan, until I had a completed model. In theory, it would be a simple process.

Sheet 13 of 13, HABS 1958

One of 13 schematic diagrams in the HAB survey. This one addresses details of doors and mouldings.

Building the first door — just one door — took several days of trial and error. Then, upon further inspection of photographs, I soon learned that between offices, there were variations in doorknob height and hinge placement, letter slot placement, and door frame depth that equated to 256 possible variations of my door subassembly throughout this one building. My workload soon ballooned. I rolled up my sleeves and got to work.

Door detail wireframe composite image

Every detail that could possibly be captured in the 3D model was faithfully recorded, including ridged brass letterplates and hand-painted window lettering.

But eventually, I finished, and captured in 3D every detail I could verify. From the ridges cast into the brass plates on the letter slots, the corners of hallways lined with intricately curved mouldings, to every sweeping curve of hand-painted lettering on the office windows – everything had now been dutifully and digitally recorded. The time to test the model had come.

To my great relief, everything snapped into place perfectly.


Miraculously, the lines in the 3D model aligned perfectly with the historical photographs.

Seeing the lines click into place on the old photograph, I felt a connection to the surveyors who had measured, scribbled figures, and drawn the details of the Montgomery Block. In the summer of 1958, in the same well-worn corridors where General Henry Halleck, Ambrose Bierce, and Adolph Sutro had trodden, these surveyors measured and recorded the historic structure for posterity. Just 13 months later, as the grand structure was being blasted and shoveled away to make room for a parking lot, the surveyors’ documents would be filed on shelves at the Library of Congress in Washington, D.C.

What would be the point of all of that surveying if the work stayed hidden?  Surely the conservationists hoped that their work would be appreciated in the future, and that someone, someday, would pore over the details of their work. My digital reconstruction of the building was an effort to decode this message from the past, and the first letters of that message were now spelled out clearly on my screen.

HABS photo, third floor hallway

This photo of the third-floor southern hallway, from the HABS, is the only known photo of either of the office wing staircases. With all details shown far in the background, the photograph reveals very little detail.


Despite limited photographic evidence, the staircases had been meticulously measured down to the last detail in one of the HABS diagrams.

Staircase wireframe composite image

Thanks to the HABS diagram’s faithful record of the staircases’ details, both the southern and northern staircases could be accurately modeled in 3D. This image shows the initial landing of the southern staircase on the second floor, one level below the view shown in the HABS photograph.

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