Embedded Files
By Sandra Schloen, May 2014
Updated August 2017
Variables can be designated as having the "coordinate" data type, making them distinctive from other types and appropriate for integrating with other built-in mapping features. Variables of this type expect an X, a Y, and an optional Z, decimal value, formatted as X, Y, Z on data entry.
Here, for example, is a variable used to indicate the Findspot of an item. Note that the (x, y, z) notation is not required, but is used by convention as a naming strategy for variables of this type.
The x, y, and z coordinate values will be maintained at whatever precision is provided by the user via data entry. On the View, coordinate data is rounded to two decimal places.
Items included in query-based mapping will know how to plot their coordinate data automatically.
Point Labels
Point Labels
As of the summer of 2017 coordinate-style points can have associated labels. A label can be any character string that you wish to associate with that point. Here we have a code entered into the Total Station when the point was shot in the field; it represents a "Bottom" elevation of a Pottery pail. This label might be noted on the excavator's top plan or in the total-station's file of points. Being able to retain the label on the point that was captured as a reference within OCHRE is a helpful option.
Coordinate Systems
Coordinate Systems
In the absence of a specified coordinate system, a geographic coordinate system (GCS) based on the World Geodetic System (WGS) 1984 datum is assumed. In this case longitude, latitude, and elevation would represent the x, y, and z coordinates respectively. This is the same reference system used by the Global Positioning System (GPS).
Often archaeologists will use a coordinate system more closely aligned with a specific excavation area, for example, a UTM (Universal Transverse Mercator) projection or even a completely custom projected coordinate system. In this case, provide OCHRE with the projection details using a Well-Known ID (WKID) or Well-Known Text (WKT) which defines the required system or projection. For example, the WKID 4326 represents the default GCS_WGS_1984 projection. A field is provided for this information on OCHRE's Variable pane.
For more information regarding the use of coordinate-type variables integrated with OCHRE's mapping features, see also Managing Point Coordinates.
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