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Help & guidance Guides to Good Practice

Depositing information

Bob Bewley, Danny Donoghue, Vince Gaffney, Martijn van Leusen, Alicia Wise (1998). Revised by Bob Bewley and Kieron Niven, Archaeology Data Service / Digital Antiquity (2011), Guides to Good Practice

Datasets selected for archiving should be accompanied by appropriate documentation and metadata, preferably also provided in digital format. As discussed in How to document your resources, the documentation which accompanies a dataset should enable a third party to make sense of the data. In addition to the documentation suggested in previously , a single set of general project-level information is also required. This is described in the general ‘Project Metadata’ section and specific examples of information that you may wish to include are provided below:

Element(s) General Description Examples / Suggestions
Description History of the Originating Project the purpose of the project
topic(s) of research
geographic and temporal limits
other relevant information
Description Information about Methods methods used to create the data set
methods used to georeference data
consistency checks
error corrections
sampling strategies employed
other relevant information
Relations Details of source materials used to create the dataset archives interrogated for desktop assessments
maps used to georeference site grids or surveys
previous excavations/evaluations of the site
data selection or sampling procedures
procedures for updating, combining, or enhancing source data
description of any known copyrights held on source material
Relations Details of how the dataset relates to other archives and publications bibliographic references to any publications about the site or project
information about any archives, museums, SMRs, NMRs, etc. which hold material related to the dataset
information about any non-public material relating to the dataset
Format Content and structure of dataset list of filenames and description of contents
type of computer on which data were created and manipulated
description of identification numbers assigned
list of codes used, and what they mean
description of any known errors
indications of any known areas of weakness
details of derived variables or coverages
data dictionaries, if available
documentation of record conversion to new systems and formats
description of the record-keeping system used to document the dataset
names of primary project staff
history of format changes to dataset
history of how the dataset has been used
other relevant information

Deposit formats

As noted at the start of this guide, copyright restrictions generally prevent the archiving of primary remotely sensed data. Where data can be freely archived and disseminated, the formats that are safest for digital preservation vary with the type of information contained within a file. As a result, recommendations are given here for the formatting of images, documentation, and metadata relating to digital resources based on aerial photographs or remotely sensed data. If aerial photography and remote sensing data is managed within a GIS environment, please refer to the GIS Guide to good practice

Image files

Image formats are commonly used to hold interpretations and rectifications of aerial photographs or remotely sensed images. While it may not be necessary to archive every single image created during the life of a project, a good archive will consist of final versions of those images important in the final analysis. The old adage often applies here: an image is worth a thousand words. Archiving a single image can often be worth more than a thousand words of documentation, but remember that if the image is to be really useful to others, it must be accompanied by background documentation explaining how and why it was created.

It is recommended that images are saved in uncompressed TIFF or PNG formats. Of these two recommended formats, PNG is preferable as this format retains information about the gamma values in images, but TIFF is currently a far more common image format for preservation. Other image formats may also be suitable and are discussed in detail in the Raster Images guide.

As also discussed in the images guide, many other formats may result in the loss of data contained within the original image, and these should be avoided as archival formats where possible. In some cases, datasets may also need to be compressed to assist in transferring information and large datasets with numerous component files are most easily handled in this way. There is always the risk of data loss, however, with data compression routines.