Drawing Newly Exposed Features of Spatial Contexts

QGIS excavation area GeoPackage layers to be used:

• [EA]_day_plan_polygons_[year]
• [EA]_day_plan_lines_[year]
• [EA]_day_plan_elevation_points_[year]

Now that you have archived features that have been removed for long-term digital curation and analysis, your will digitize features that are newly visible in the relevant orthophoto(s). First set the map canvas scale to a scale between 1:5 and 1:10 (depending on the features) so that appropriate detail can be captured. Do this by typing 5, 6… or 10 into the Scale bar below the map canvas.

Drawing polygons in the [EA]_day_plan_polygons_[year] layer #

1. Select the [EA]_day_plan_polygons_[year] layer in the Layer panel and Toggle Editing to on. Use the Add Polygon Feature tool to create new polygons as needed, following the same process as used for creating spatial context polygons above (click to place vertices; right click to finalize and create the feature; fill out the attribute table as described below).
   1. Make sure to turn on Snapping for the “Active Layer” in the Snapping Toolbar (if it is not visible, right click in the toolbar and check the Snapping Toolbar checkbox). This will allow you to avoid overlapping polygons and to allow perfectly matching boundaries between polygons.
2. Fill out the Attribute Table with the correct “polygon_type” as you proceed. When you save edits, the symbology will be updated automatically based on the data in the attribute table.
   1. Areas like pebble concentrations, possible pits, and other patterns visible on exposed surfaces yet not yet articulated enough for identification should be given the polygon_type of “area of interest”.
3. No other attribute table data needs to be entered at this time for general day plan illustrations. However, if the polygons you are drawing are part of a named and numbered feature (e.g., a wall, a paved surface), you should fill out the context_key and context_type fields in addition to the polygon_type field.
4. Continue this process until all features in the orthophoto have been drawn.
5. Make sure to save your edits frequently and Toggle Editing to off when done.

Drawing lines in the [EA]_day_plan_lines_[year] layer #

1. If you have drawn the stones or other features of a newly identified archaeological feature (e.g., a wall, pit, circular feature, etc.), you should also add an “outline”. This is done using the [EA]_day_plan_lines_[year] layer.
   1. Open the attribute table for the day plan lines layer, and Toggle Editing to on. Select “Add Line Feature” from the toolbar and digitize the desired line (click to place vertices; right click to finalize and create the feature (ending with the last clicked vertex); fill out the attribute table as described below).
   2. Unlike polygons, lines are composed only of line segments. You do not need to draw a closed shape to draw a line. If you are drawing the outline of a pit or circular feature, the outline should surround the whole feature; if you are drawing a wall, it is preferable to draw a separate line for each side of each contiguous segment of the wall.
   3. Line outlines should match the exterior boundaries of the features that compose the spatial context. To make this possible, turn on Snapping for the “All Layers” in the Snapping Toolbar. This will allow you to avoid overlaps and make outlines correspond exactly to the features that are being outlined (see Figure 2).
   4. There are also line options for “continuations” and “reconstructions”; use these lines to show interpretations of where a wall or feature may have continued in antiquity, but is now missing.
   5. Fill out the attribute table with the proper line_type (e.g., outline, continuation, reconstruction)
   6. Continue this process until all features in the orthophoto have been drawn.
   7. Make sure to save your edits frequently and Toggle Editing to off when done.

Adding elevation points from the [EA]_day_plan_elevation_points_[year] layer #

Finally, you can use the [EA]_day_plan_elevation_points_[year] layer to add new elevations for the context you are working on.

1. First, make sure the attribute table for all previous elevation points has been updated with “context_key” for each point, in addition to “point_type”.
2. You have previously been working with the orthophoto (the “P” file) for this context; now, open the DEM (the “Z” file) for the same context.
3. Select the [EA]_day_plan_elevation_points_[year] layer in the Layers panel and Toggle Editing to on.
4. Select “Add Point Feature” in the toolbar, and place points in each part of the context in which the depth has significantly changed by clicking on each location and entering “bottom” for type in the Attribute table when prompted. Save edits along the way and when finished.
5. With editing still on, open the Attribute Table and select all the new points you’ve just created. Open the Field Calculator and check the checkboxes for “Only update X selected features” and “Update Existing Field”. Select “elevation” from the dropdown menu of existing fields, and enter this expression into the expression window: raster_value (‘DEM’,1,$geometry)
   1. Be sure to substitute the Z photobatch you are using for DEM in the above expression
   2. Be sure to use single, straight quotation marks in the expression (not curly marks)
   3. If successful, you should now see values in the elevation column that have been extracted from the DEM. Save edits and Toggle Editing to off.
6. If you have recorded elevation points using the GNSS, locate the associated shapefile in the gnss folder, add the layer to your project, and copy and paste the needed points to your [EA]_day_plan_elevation_points_[year] layer, making sure that proper attribute data is added as well.

At this point, you should have made all the edits necessary for a single context. Repeat the above steps until you have made all the necessary edits for all contexts excavated today.

REMEMBER: The Day Plan should show only what is visible at the end of each day. If you excavated multiple contexts in the same area in the same day, you may need to make a, b, and c versions of that day’s day plan to ensure all contexts are represented. This will allow them to be recorded for posterity and archived.