Tag Archives: elcovision

Sharing: Middlebrook Avenue

Two more screenshots to share, this time of a streetscape project on Middlebrook Avenue here in Staunton, VA. The first shows a virtual aerial view of the the automatically created point cloud, the second of the assembly of photos used to create the point cloud. Both are screen shots from Elcovision software.

Middlebrook Avenue point cloud

Middlebrook Avenue Photos

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More lost blog posts: Arc de Triomphe

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L’Arc de Triomphe

Re-posted here are some of the images collected this past summer of the Arc de Triomphe in Paris. These were made as a sort of demo project following some training sessions in which I was learning how to create rich 3D point clouds from photographs.

Axonometric view of point cloud

Looking at these images now, they don’t seem terribly “rich” as 3D point clouds – I’ve since learned how to do this work  better – but they are a good start. For one thing, they were the successful resolution of an automatic analysis module ( a big time saver).

“RCP” of point cloud

Individual photos with point measurements shown

Screen shot from Elcovision

Stone Barn at Morven Park

Below is 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 1:48 (or a quarter inch equals a foot) when printed at 300dpi. The individual images are posted below.

partial elevation (LEFT) qtr scale at 300dpi

partial elevation (CENTER) qtr scale at 300dpi

partial elevation (RIGHT) qtr scale at 300dpi

Below is 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

Documentation of a sculptural element using Photogrammetry

Test subject

In August I shot a variety of sculptural objects with a mind towards testing the capabilities of photogrammetric software to create useful point cloud descriptions of objects that are difficult to assess conventionally. This urn represents a little of both – parts of its form is sculptural, organic, non repeating, while parts are more classical or architectural in  nature.

Photo with magnifying glass (or ‘loupe’) in Elcovision software

For this study I processed 72 photographs which consisted of three sets of images: two rings around the urn at 16mm and a half arc at 50mm (spatial constraints made it impossible to go all the way around at 50mm).

Point Cloud and photo stations (in red)

60,000 points were generated to describe the urn itself.  When viewed orthographically the point cloud behaves like a drawing – or can be the basis for a measured drawing.  The sculptural relief of the figures still escapes precise documentation in the point cloud, I think.  Laser scans still do this fine detail better, it seems.  But this point cloud – even as it is – in combination with  the photographs do so much more than what photogrammetry was able to do even a year or so ago. I think its catching up to laser sourced point clouds and doesn’t require the huge equipment investment.

Orthographic View of Point Cloud

Screenshot

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.

Test Project: Marquis Building

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)

Left Photo

(Note: I used considerably more photographs than just these three shown here)

Right Photo

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

Mosaic Images from multiple view points simultaneously

Maria Mitchell Hybrid Drawing

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

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.

Maria Mitchell 10Maria Mitchell 9

Maria Mitchell 8Maria Mitchell 7Maria Mitchell 6Maria Mitchell 5

Maria Mitchell 11

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

Discovering Photogrammetry in France

I first encountered the concept of architectural photogrammetry while working as an architect in Paris in 1990 -and was immediately intrigued. So much so that I decided to swap my job with a 45 minute commute into the city for a new job just a short bicycle ride away (in the town of Egly)  in order to learn how to do this work.  Simultaneously I had to learn how to draw with a computer; up until then I had only drafted with pen and pencil (plastic leads for working drawings).  It was a lot to take in, but I think its fair to say that I loved it.

digitizing puck

digitizing puck

Back then, the process was nearly completely analog: We shot film and had it developed into 8″x10″ prints.  These were then taped onto a large format digitizer so that points on the photos could be communicated to software running on a PC.  Then after a photogrammetric analysis of this information was completed, we made drawings that were plotted to scale – and it was these prints that were the “deliverable” product desired by our clients.

I remember seeing a number of photos taped onto a digitizing table and watching my colleague Herve use the digitizing puck to point to the same location on a building as seen from various points of view and then push a button and seeing the point location appear in 3-D coordinates in an CAD drawing on a computer screen.  It seemed magical.

As more and more points were measured in this way, I could start to see the shape of the building.  This became even clearer as points were connected into lines and polylines; the “point cloud” was becoming a “wire frame”.

When I first got out of architecture school and was working for a firm in New York City, the first thing I had to do was to learn how to make measured drawings of existing conditions.  It was messy, confusing work on site and often yielded error-ridden results in the office that required repeated return visits to understand and clarify what was really happening architecturally.  When I saw a dimensionally accurate 3-D model representing an existing structure being created from a handful of photos, I was hooked.  Nobody I knew was doing anything like this in the United States.

 

Triumphal Arch Jardin de Tuileries

Triumphal Arch Jardin de Tuileries