{#- vim: set ft=htmldjango : -#} {% from 'docs/vis-documentation-macros.html' import full_documentation_link with context %} {% if show_figures %}
The map pane in clustered map mode.
{% endif %}

The map visualizes the geographical aspect of the data, i.e., evidence for the presence of religious groups at different locations.

Content

Map Glyphs

Pieces of evidence are represented by so-called map glyphs. By default, these map glyphs are clustered (i.e., aggregated, or summarized).

This aggregation depends on the data currently active and on the current zoom level of the map; that is, once the zoom level or filters are changed, the map is populated with glyphs according to the aggregation rules; simply panning the map will not affect the map glyphs. More details are given below.

This map mode is called clustered. It can be changed in the settings (cf. the {{ full_documentation_link('map-unclustered-mode', 'info text below', true) }} and the info text of the {{ full_documentation_link('settings-map-mode', 'Settings pane') }}).

Aggregation of Locations

Locations are aggregated to eliminate overlap, and so, by default, each map glyph represents one or more cities, depending on the zoom level. Note: For this aggregation, all places are treated equally; that is, the distribution of religions of place A and place B is combined without taking into account any further aspects of A or B.

When hovering over a glyph, it loses opacity and the aggregated locations are indicated on the map as small turquoise dots (maybe partially covered by the glyph). While hovering, a tooltip is also shown, which provides information on the number of pieces of evidence, of religions, and of places related to the glyph. As long as the glyph does not aggregate more than five places, the toponym, geographical coordinates, and more information on the pieces of evidence belonging to that place are provided for each place. Even more details are provided if the glyph only represents one place.

Aggregation of Religions

A map glyph consists of up to four circles, each representing a general religious affiliation with a distinct symbol and color:

Generally, multiple religious groups belonging to the same general religious affiliation are aggregated to one circle. This circle then functions like a pie chart: in religion mode (set by default), each piece of the pie chart represents a different religious group in its respective color and the piece's size shows the amount of pieces of evidence of that religious group relative to the overall evidence of its general religious affiliation. In confidence mode, the division of the circle or pie chart is based on the pieces of evidence attributed with different levels of confidence and is colored accordingly.

However, if, regarding all map glyphs currently displayed, no more than four religous groups are to be represented, there can be more than one circle representing a general religious affiliation. For instance, if only COE (Church of the East), SYR (Syriac Orthodox Church), and SUN (Sunni Islam) are filtered using the religion view, any given map glyph cannot have more than three circles. Accordingly, both COE and SYR will be represented by an individual circle with a cross and the respective color. Note that this aggregation may result from other filters or interactions with the map, not just filtering using the religion view, as the map glyphs are dynamically altered based on many different criteria.

Note that placement and aggregation of map glyphs depends on the data currently active as well as the zoom level—not, however, on the current center of the map. In other words, all map glyphs currently displayed include map glyphs outside the current scope of the map that will appear when panning the map.

If in at least one glyph currently displayed multiple religious groups are aggregated into one circle, this same aggregation will apply to all other glyphs as well, even if, in sum, they have less than four circles and would not be aggregated. Otherwise, the perceived variety and distribution of religions would be skewed; for example, a location with only two Christian groups would be represented by a map glyph with two circles for Christianity, while a location with many Christian groups as well as other groups would be displayed with only one such circle.

In only active mode, data that has been filtered out disappears from the map. Note that this can lead to glyphs having less circles, if, for example, all Christian data of a glyph has been filtered out. In all data mode, data that has been filtered out is indicated by less saturated colors.

Unclustered Mode

{% if show_figures %}
The map pane in unclustered map mode.
{% endif %}

The aggregation or clustering of places can be turned off in the settings pane. In this map mode, called unclustered, each location is represented by an individual glyph. Here, the glyphs consist of smaller circles, one for each religious group. These circles are arranged in a hexagonal pattern. Overlap can and will happen in this mode, even when zooming out to a relative small scale. Z-ordering of the glyphs ensures that glyphs with fewer religious groups appear in front of larger glyphs with more religious groups.

Note: For both modes, the specific way of representing the data should be considered when interpreting the results.

Layers

The map provides multiple layers, which can be controlled from the layer control in the upper right corner. One of two base layers is always selected and shown: by default, a layer based on a custom map from MapBox is selected, which shows topological features but no geo-political borders (i.e., borders of modern nation states). As an alternative, a map provided by the Digital Atlas of the Roman Empire (DARE) can be selected as the base layer.

In addition, one or more overlay layers can be shown:

Markers
consists of the clustered or unclustered map glyphs. It is shown by default.
Diversity Markers
displays all locations, without clustering, each colored according to its religious diversity (i.e., the number of distinct religions present in each place). The color scale Viridis is used, where low values are mapped to violet, and high values to yellow.
Diversity Distribution
shows an estimation of the religious diversity and is colored according to the same scale as the diversity markers.
Distribution
shows an estimation of the density of pieces of evidence.

Note: The two layers for diversity (one displaying markers, the other displaying a heatmap) are alternative representations of the same data. Thus, they should not be both displayed at the same time. Similarly, the two layers using markers (the default one displaying map glyphs and the one displaying markers of diversity) should not be shown together.

What the Map is not Showing

Damast visualizes religious constellations in cities and towns of the Islamicate world with static Non-Muslim communities. The map does not depict a representation of the population density in the medieval Middle East. In other words, an area with no or only few map glyphs is not necesarrily less populated than other areas. The map makes no claim to be complete, nor does it show the general distribution of religions in a given area.

Empty areas on the map can have multiple reasons:

Furthermore, in clustered mode, the overall size of the map glyphs (i.e., the number of circles) does not directly correlate with the number of religions or pieces of evidence; for instance, a map glyph with three circles does not necessarily represent more pieces of evidence than one with only two circles.

Interaction

The map can be interactively zoomed and panned (i.e., the center of the map is moved).

Selection

Clicking on a map glyph will select the represented places, brush the represented data, and link the respective data in the rest of the views. Likewise, brushing data in other views will link the respective places in the map. Also, selecting a place in the location list will pan the map to center on that place. Map glyphs that are not linked will be displayed in less saturated colors. Linking persists when zooming, even if clustered glyphs split up or merge. Note, however, that a map glyph often represents more than one location. In this case, all of the circles belonging to the glyph are highlighted, even if the linking only refers to part of the evidence. For instance, a place from the location list, which only has pieces of evidence of the general religious affiliation Christian, may be selected. If this place is aggregated with other places that additionally have, for instance, Islamic pieces of evidence, both the circle with the crescent as well as the one with the cross are highlighted.

Link to Place URI Page

When hovering over a map glyph, more information is shown in a tooltip (cf. {{ full_documentation_link('map-glyph-hovering-tooltip', 'here', true) }}). Normal selection (cf. {{ full_documentation_link('map-glyph-selection', 'above', true) }}) will link the places represented by the glyph in the {{ full_documentation_link('location-list', 'location list view') }}. From there, the place URI page of each place can be opened for more information. It is also possible to go to the place URI pages directly from the map: Holding the shift key down and left-clicking a glyph will directly open the place's URI page if the glyph represents only one place. If it represents more than one place, a dialog window opens on top of the visualization with a list of the place names. Each of the names functions as a link to the respective place URI page.

Geographical Filtering

{% if show_figures %}
The map pane with the Geoman editor open, and a polygon being edited.
{% endif %}

Evidence can be filtered by geographical location. This is done by drawing the respective bounding shapes into the map. For this, the Leaflet plugin for Geoman is used. The respective tools to control the filters are available by clicking on the button with the funnel in the upper left corner of the map, below the zoom buttons. The button then expands to a set of controls, arranged in three blocks: the first block for adding elements, the second for editing them, and the third to apply, remove or revert the filters. These are described in detail below. Tooltips are shown when hovering over the individual buttons.

The first block is for adding new elements to the bounds.

The second block contains controls for editing existing elements. It is possible to

Note that polygons can only be moved or removed individually before they have been applied as filters.

The last block contains controls to apply the created bounds to the dataset filter.