This vector layer type can be used to display the location of features (or one of each feature's observations) on a map. You can connect any number of features to layers of this type. The layer belongs to the layer type class Feature data untyped.
The layer type will show LSO of all connected features. Connected features that have no spatial support will not be shown on the map. For features that have spatial support on observations the location of one of the observations will be shown (by default the latest observation, see Observation date setting).
If the LSO of features connected to this thematic layer is given in another spatial system or another spatial reference system than the system used for the map view definition the LSO will be transformed and - if transformation is possible - displayed. See the chapter transformation of spatial data for more details.
If a feature is connected multiple times (e.g. through views) it will be displayed only once. Table 1 shows the settings available for this thematic layer
Setting |
Description |
Hide contents |
If selected the layer's contents will not be shown. However the layer's contents can still be used to define zoom extents. |
Defines zoom extents |
If selected the contents of this layer and all other layers with this flag set will be used to calculate the boundary for zoom extents. |
Report layer |
Defines that the layer is used as a report layer. If the map view is used in a report that loops through features the features in this layer will be automatically exchanged. |
Feature limit |
The maximum number of features that will be drawn. Even if more features are connected, the map will never show more features than defined by this setting. Displaying many features on a map view might take a long time for getting and rendering the data. This setting should avoid long rendering time if you accidentally connect a huge number of feature (e.g. by connecting a view) |
Expand container features |
If this option is set bound container features are expanded and the contents of the container feature are shown. |
LSO display |
The location of a feature (or the observation) can be displayed on the map either as point or as the original geometry. If displayed as point and if the original geometry of the displayed feature or observation is not a point the geometry will be converted to a point geometry (for details on this conversion see below) |
Feature label |
Defines if a label is added to drawn features and what text is shown with the label. You can choose from a predefined list of formats: •None •Feature name •Feature type + feature name |
Show elevation |
Defines if the elevation of each feature is added to the feature label. |
Observation status |
A date & time value that will be used to pick the observation that defines the feature location if the features spatial support is on observations. The actual location shown will be the location of the observation that is nearest to this specified date & time. If not given the system will use the latest observation available. |
Table 1: Settings for the thematic layer Feature location
Table 2 shows visualization settings that influence how features are displayed. If these settings are not given the system will try to get visualization settings from the Feature type, if it cannot get it from there the system will choose default settings
Setting |
Description |
Label color |
Defines the color of the label text |
Label size |
Defines the size of labels. Given in points (pt). Note that labels are not resized if the map is zoomed. |
Foreground color |
Defines the color for the graphical elements used to display the feature's geometry and data. |
Background color |
Defines the color that is used to fill polygon geometries. |
Line style |
Defines the line style that is used to draw line and polygon geometries |
Line thickness |
Defines the thickness of lines used to display features |
Point display type |
Defines how objects are displayed. Symbol: objects will be shown with the selected point symbol Bitmap: objects will be shown with the selected bitmap Feature type icon: objects will be shown with the feature type icon Symbol & bitmap: objects will be shown with the selected point symbol plus the selected bitmap. The bitmap is placed with a small offset Symbol & feature type icon: objects will be shown with the selected point symbol plus the feature type icon. The icon is placed with a small offset |
Point symbol |
Defines the symbol used for point geometries, the same symbol is also used if line or polygon geometries are shown as point |
Feature type icon size |
The size of the feature type icon if the point display type is set to Feature type icon or Symbol and feature type icon. |
Point symbol size |
The size used for point symbols. The size is given in pixels. |
Symbol image |
The image used if point display type is set to Bitmap or Symbol & Bitmap. Allows the selection of a PNG image. We suggest to use only small images with transparent background. |
Table 2: Appearance settings for the Feature location layer type
Midpoint calculation
When the Map view shows the location of an element as Midpoint that midpoint is calculated differently for different types of geometries and differently for projected and geographic coordinate systems, see tables 1 and 2 for detail.
Geometry |
Midpoint calculation |
Point |
Midpoint is same as point |
Multi point |
Midpoint is Centroid of the Convex hull if the convex hull is a polygon. Midpoint is Centroid of envelope if convex hull is a line. |
Line |
Midpoint is Centroid of the Convex hull if the convex hull is a polygon. Midpoint is Centroid of envelope if convex hull is a line. |
Multi-line |
Midpoint is Centroid of the Convex hull if the convex hull is a polygon. Midpoint is Centroid of envelope if convex hull is a line. |
Polygon |
Midpoint is Centroid of Polygon |
Multi-Polygon |
Midpoint is Centroid of Convex hull of Multi Polygon |
Table 1: Definition of Midpoint for different types of geometries on a projected coordinate system
The convex hull of a geometry defined on a projected coordinate system is the smallest convex geometry that completely encompasses all the points in a given instance. A convex geometry is one in which no interior angle is greater than 180 degrees, so that the sides do not ever bend inwards or contain indentations.
The envelope of a geometry represents the smallest axis-aligned rectangle that completely encompasses every part of the geometry.
Geometry |
Midpoint calculation |
Point |
Midpoint is same as point |
Multi point |
Envelope center |
Line |
Envelope center |
Multi-line |
Envelope center |
Polygon |
Envelope center |
Multi-Polygon |
Envelope center |
Table 2: Definition of Midpoint for different types of geometries on a geographic coordinate system
The Envelope center is the average position of all vectors that describe the location of each point in the geometry from the center of the earth. This is a very simple approximation of the center point of any type of geometry based on a geographic coordinate system.
