Hardware and Set up

musuemone

Method One:

Photogrammetry: Photogrammetry finds the three-dimensional structure of a subject by analysing the sequential change of position of the camera sensor relative to the subject.

Equipment List:

  • Canon DSLR D60
  • Canon DSLR D70
  • Spare Battery packs for cameras
  • Tripod
  • Light Box x 2
  • Lighting
  • Turntable
  • Photogrammetric Scale Bars
  • SD Cards
  • Lenses
  • Black drop cloth
  • Chalk Powder
  • Latex Gloves
  • Floral foam
  • Multi-socket Extension leads
  • Wooden plinths

Objects Captured

  • Cecilia Statuette
  • IHS Altar Stone
  • The Empress of Austria Vestments
  • Votive Offering One
  • Votive Offering Two
  • Votive Offering Three
  • Egyptian Statuette
  • Penal Cross
  • “Power” Ciborium
  • Ceremonial Chalice (And Patten)

photogrammetry

Preparation:

  • Prepare turntable.
  • Prepare additional support.
  • Change backdrop.
  • Test shots and adjust lighting if required

Number and angle of images:

  • Isolated interior object:
  • Shoot at a hemisphere around object
  • Overlap 60% or more
  • Photograph image at three separate elevations
  • 20-30 images per elevation.
  • Additional images for the more detailed areas of the statuette including the hands and back of the neck.

Method Two:

Close Range 3D Laser Scanning

Equipment List

  • NextEngine 3D Laser Scanner
  • Auto Drive (turn table)
  • Part Gripper

Objects Captured

  • Old Altar Stone
  • Ivory Statuette

laser-scan

Preparation:

  • The object was placed on the auto drive – it did not need to be secured using the part gripper.
  • Align the object on the turntable using the viewing window to ensure that the object is visible within the scanning field.

General Comments

The equipment was transported and set up on the morning of the data capturing. The initial set-up of the 3D laser scanner and two photo stations took approximately one hour, including testing: the museum lighting posed challenges and lighting was adjusted and a number test captures were carried performed.  When considering where to set up the work stations access to power points was a key consideration. Once started, data capture continued at a good pace.  The team had a high degree of practicality and initiative, those who were capturing applied themselves to the task, those who were not assisted.

The equipment set-up was adjusted throughout the day, in line with the requirements of the individual items. For example, many of the small items required additional supports. This support was provided by floral foam (oasis). Wooden blocks were also used as plinths for smaller objects.  There were several objects with degrees of reflection, particularly the Chalice, Ciborium, and several wooden crosses.  In these cases, lighting was adjusted where possible.

The background was also altered for individual items. This was carried out with the next step of data processing in mind.  Lighter objects such as the ivory ciborium required a black backdrop to facilitate masking.

The largest piece captured using photogrammetry was a full set of Vestments. This was captured by moving a large floor exhibit, with kind permission from the curator, temporarily placing the mannequin holding the Vestments into a well lit area. The vestments continued to be problematic due to the surrounding exhibits causing light pollution. A large heavy black cloth was used to provide backdrop.

There were no weights brought to counter balance the studio lights, which are top heavy. Personal backpacks were required to support the base.  Latex gloves were brought on the day.  However, the curator provided the team with cotton gloves which were worn when handling the items as he was worried that the latex gloves may leave powder residue on the objects.  The curator handled the more fragile items, such as the ivory ciborium.

Prior to data capture, the team selected ten objects of interest and included a number suggested by Dr. McKeith.  The project manager set out a schedule for all ten objects to be scanned or photographed. One the day, the team captured data for fourteen objects.  However, not all the previously selected were captured.  This was due to practical issues. For example, the team had hoped to capture the museum’s amputee Jesus statue. However, it was not possible to move the statue on the day and there was not sufficient space around the object to create a reliable dataset.

The initial intention was to use the 3D laser scanner to capture four objects. However, scanning took significantly longer than originally anticipated and two objects were captured using the scanner.

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