Metadata for a digital object consists of several levels and is divided into two major categories 1) metadata for data collection (referred to as acquisition metadata) and 2) metadata for data processing. Acquisition metadata is further divided into two major sub-units — project and scan level. Processing metadata is characterised by key processing steps including scan registration, mesh preparation, mesh finalisation, and additional product creation. Metadata entries for acquisition and processing metadata are shown in the tables below.
Table 1: Project level metadata (Payne 2010, 3.2.1)
| Element | Description |
|---|---|
| Project name | Name of the project |
| Name of monument, survey area, or object | Name of object, monument, or area scanned |
| Monument/Object number | The ID number or code, if applicable, of the object or monument |
| Survey location | Exact location of survey with complete address and/or coordinates |
| Survey date(s) | Dates(s) of survey |
| Survey conditions | The overall weather trend during survey (sunny, overcast, indoors, etc.) |
| Scanner details | Details of the instrument(s) with serial number(s) and scan units |
| Company/Operator name | Details of company and/or scan operator |
| Control data collected? | If yes, then list control_file_name.txt. |
| Turntable used? | Yes/No |
| RGB data capture? | If yes, then specify whether: - Internal or external? - Was an additional lighting system used? If yes, then provide a brief description of the lighting system. |
| Estimated data resolution | The estimated data resolution across the monument or object. |
| Total number of scans in project | Total number of scans |
| Description of final datasets for archive | What datasets will be archived (include file names if possible) |
| Planimetric map of scan coverage areas | If applicable, then provide the image name. |
| Additional project notes | Additional notes |
| Images from survey | Optional, if yes, then provide the image file names |
Table 2: Scan level metadata (Payne 2010, 3.2.2)
| Element | Description |
|---|---|
| Scan filename | The name of the scan. A suggested filename for original raw scans for archiving is in this format: ProjectName_scan1.txt. |
| Scan transformation matrix | The name of the transformation matrix used in Global Registration |
| Name of monument/object area | |
| Survey date | |
| Scan number | The number of the scan in scan sequence e.g. 3 of 18. |
| Number of points in scan | |
| Additional scan notes | |
| Scanner technology | TOF/Phase/Triangulation |
| Data resolution | The data resolution at specific range. |
| First or last return (TOF scans only) | |
| Frequency settings (phase scans only) | |
| Noise settings (phase scans only) | |
| Camera exposure settings (If RGB acquired) (phase scans only) | |
| Lens or FOV details (triangulation scans only) |
Table 3: Scan registration metadata (Payne 2010, 3.3)
| Element | Description |
|---|---|
| Name of registered dataset | Filename for the dataset, a suggested naming structure for registered dataset for archiving: ProjectName_GR.txt |
| Total number of scans used in registration/total number acquired | |
| Global registration error in units | |
| Total number of points in final registration |
Metadata for each of the derived products was also needed. This included the pre-mesh point cloud.
Table 4: Pre-mesh point cloud metadata (Payne 2010, 3.4.1)
| Element | Description |
|---|---|
| Name of pre-mesh dataset | The dataset's filename, a suggested naming convention for pre-mesh point cloud dataset isProjectName_GRE.txt |
| Number of points in file | |
| Overlap reduction | (Y/N) (optional) |
| Smoothing | (Y/N) (optional) |
| Subsampling | (Y/N) (optional) |
| Colour editions | (Y/N) (optional) |
| Point deletion summary |
Table 5: Polygon mesh metadata
| Element | Description |
|---|---|
| Name of mesh dataset | The file name, a suggested naming convention for the polygonal mesh dataset is *ProjectName_origmesh |
| Estimated mesh spacing (in units) | |
| Holes filled | (Y/N) |
| Smoothing | (Y/N) |
| Colour editions | (Y/N) (optional) |
| Healing/despiking | (Y/N) (optional) |
| Total triangle count (post-editing, pre-decimation) | |
| RGB colour included | (Y/N) |
| Data reduction | (Y/N). If yes, give percentage of reduction from original |
| Coordinate system adjustment | (Y/N). If yes, a transformation matrix must also be provided. |
| Additional processing notes |
Table 6: Decimated mesh metadata (Payne 2010, 3.4.2)
| Element | Description |
|---|---|
| Name of decimated mesh dataset | The file name, a suggested naming convention for the decimated polygonal mesh dataset isProjectName_decimesh_50pcnt for decimated mesh e.g. by 50%. |
| Total original triangle count | |
| Decimated triangle count | |
| RGB colour preserved from original dataset | (Y/N) |
A fully 'worked example' of these metadata for a single object from the Hampson Museum are provided in the G2GP.
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| File last updated: Tue Jun 28 2011