Historic Trolley Barn

Trolley Barn at San Jose's History Park

Earlier blog entries addressed the concerns about the limitations of laser scanning for historic documentation. One of the most glaring examples of the limits of this technology is the problems encountered when scanning non reflective objects.

Interior Laser Scan of HSJ Trolley Barn
NVentum, LLC.

Lasers capture the light reflected off of the object being scanned. Objects and colors that absorb light are difficult, if not impossible to capture clearly. This was clearly demonstrated during our initial scans of the interior of History San Jose's Historic Trolley Barn.

The Trolley Barn was built in 1984 as a place to restore and house historic trains and trolley cars. In addition to the trains and trolley cars, the barn also houses historic automobiles and old factory machinery.

At first glance, the preliminary laser scans of the interior of the barn provide the viewer with a great amount of detail. The details of the signage in the back ground, the outline and the detail of the 1913 Metz in the foreground are promising images and a great start to the project.

1913 Metz- HSJ Trolley Barn
Laser Scan by NVentum , LLC.

As we continued our process, the concerns moved from the laser capture process to texture mapping. How would the photo overlay work against a laser scan with so many non-reflective objects? The automobiles, the trains and much of the machinery had major elements that were finished in black or flat black. However, this 1913 Metz was finished in a very dark blue and the laser scans showed great promise.

Classic Autos- HSJ Trolley Barn

As you can see by the scan on the right, the two classic automobiles were captured very clearly in the laser scan, or so it appears. The automobile in the foreground is dark blue in color. The automobile in the background is very dark blue with black fenders. Understanding the laser's limitations, I was pleased with the initial images. However, the images that you see in this still photo are deceiving. What clearly appears as two dark colored antique automobiles is actually an illusion. The areas of the vehicles that appear black are actually areas of the scan that are devoid of all information. The laser was unable to capture any data at all, it is literally a "hole" in the scan. One of the main benefits of laser scanning technology is the ability to store and extract information from the model. While the scans of the automobiles appear to have quality information, the lack of data in this scan means the user is unable to gather critical details about the vehicles; its dimensions, the condition of the body, finish and metal. Though, at first glance this technology appears to be the perfect documentation tool.

History San Jose- Trolley Barn Machinery
Laser Scan by NVentum, LLC.

 This "mass" of equipment to the left is actually an amazing collection of antique machines and equipment used in factories at the turn of the century. The majority of these machines are finished in either black or flat black. As you can see from the scan, much of the detail of the machines is missing or indecipherable. There are gears, pulleys, drills and a host of belts and levers that were not picked up by the laser and cannot be seen clearly in this scan. Looking at the scan from other angles reveals a void of information similar to the scans of the automobiles.

The scan below was actually taken from a 360 degree scan of the 1913 Metz above. This is the Historic Trolley #124 that is still in use at the San Jose History Park.

History San Jose's Trolley No.124
Laser Scan by NVentum, LLC.

Trolley No.124
Photo Courtesy of History San Jose

Future blog post will document the reality capture and mapping of the Historic Pasetta  House located on the campus of the San Jose History Park. The goal is to feature the Pasetta House as the museum's first extensive BIM structure and data based model exhibit. Stay tuned for new blog post, updates and unique solutions to the challenges of  "Capturing History"