Hybrid Drawings & Mosaic Imagery

Hybrid Drawings are a mixture between measured line drawings, rectified photography, and 3-D point clouds.

In broad terms, a hybrid drawing is any drawing that mixes and superimposes a variety of ideas, techniques or media into a new, meaningful image – something that architects & designers have long gravitated towards. The hybrid drawings that I create for historic preservation projects are special sub set of this general category because they are measured drawings.

jackson square

Orthophoto of the Cabildo – St. Louis Cathedral – Presbetère facing Jackson Square

Chartres Street – New Orleans, LA

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The Old Senate Chamber – Maryland State Capitol – Annapolis, MD

ceiling orthophoto center cropped

Ballroom ceiling at the Townsend Mansion – Washington, DC

ceiling orthophoto center cropped detail

Detail

 

 

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Structures on Portsmouth Island, North Carolina

 

Hybrid Drawing

Hybrid Drawing

 

 

The Gardeners House at Mount Vernon

 

Fidelity to the real size and shape of existing surfaces.

Hybrid Drawings make dimensional accuracy the conjunction point between various digital media.  When a line drawing – either as a projected elevation (in 2-D) or as a “wire frame” model (in 3-D) – accurately represents the real world size and shape of a surface, it can be superimposed over another description of the same surface in a different media. In my work these additional media include both rectified photographs (aka ortho-photos) and 3-D point clouds derived through photogrammetry and/or laser scanning.

Merging CAD delineation with rectified photography produces a hybrid drawing.  These different types of description can occupy the same “space” because they each depict the same object or condition – albeit in different ways.  The line-work establishes precise edges between vertices while the pixels describe material color and condition. In short, measured hybrid drawings integrate the quantitative description of vectors with the qualitative description of pixels.

When considering a hybrid drawing, one wonders: is it a photograph that behaves like a drawing (since it is scale-able) or is it a drawing that looks like a high quality photograph? The answer is yes!

The Virginia State Capitol

How are hybrid drawings delivered/shared?

Typically I deliver measured hybrid drawings in AutoCAD format in which the line-work is composed of AutoCAD vector entities and the raster imagery consists of JPG images that are referenced into the drawing.  Often, the raster images are many (created from different vantage points) thereby creating a mosaic image of the subject.

HABS Standards have long dictated that good professional practice in documenting existing structures should include both measured drawings and photographs. Hybrid drawing techniques allow these two types of documentation to work together in a new and powerful way.

 

Mosaic Imagery

A powerful Mosaic Image is created when a number of “ortho-photos” are assembled together into an accurate line drawing in CAD format. This technique provides a way to create a photographic image that can “see around” columns, trees or other visual obstructions – allowing a surface to be viewed from multiple viewpoints simultaneously.

Nine individual photographs

Measured Drawing to provide framework

Individually rectified images assembled into framework provided by drawing

Images blended together to create mosaic image

This same technique can be used to create street-scape views that capture large amounts of architectural data on an urban scale.  See also the project page for work I did in Vladivostok (Russia).

Beverley Street in Staunton, VA

See also this blog post which discusses the difference between multiple point of view mosaic images (such as those shown on this page) and single point of view mosaic images, also known as panoramic images (sample below)

Panoramic image of Ledoux’s Royal Saltworks

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