change structure to remove duplicate introduction topic

Signed-off-by: Martin Fiebig <[email protected]>

content/geometry/object-classes.adoc

@@ -1,6 +1,22 @@
 = Object classes
 
-* xref:../object-vehicle/vehicle-index.adoc[leveloffset=+3]
-* xref:../object-human/human-index.adoc[leveloffset=+3]
-* xref:../object-environment/environment-index.adoc[leveloffset=+3]
-* xref:../object-other/other-index.adoc[leveloffset=+3]
+In {THIS_STANDARD}, an object class is a collection of similar objects.
+Examples of object classes are vehicles, humans, and road networks.
+Each instance of an object class is described by the same properties, but has
+individual property values.
+
+The {THIS_STANDARD} standard supports the following object classes:
+
+* xref:../geometry/object-vehicle/vehicle-index.adoc[Vehicle]
+* xref:../geometry/object-human/human-index.adoc[Human]
+* xref:../geometry/object-environment/environment-index.adoc[Environment]
+* xref:../geometry/object-other/other-index.adoc[Other]
+
+If a human is clearly distinguishable from a vehicle, then both the
+human and the vehicle are represented by two different objects respectively. Examples are
+bicycles, motorbikes, or scooters, where the human and the vehicle are
+perceived as separate entities.
+
+The other object class comprises all objects not yet specified by {THIS_STANDARD}.
+It includes all objects that aren't specified by type specific object classes.
+Definitions in type specific object classes overwrite the specifications in the other object class.

content/nav-openmaterial.adoc

@@ -19,7 +19,6 @@ include::use-cases/use-cases.adoc[leveloffset=+1]
 include::geometry/introduction.adoc[leveloffset=+2]
 include::geometry/general.adoc[leveloffset=+2]
 include::geometry/object-classes.adoc[leveloffset=+2]
-include::geometry/object-introduction.adoc[leveloffset=+3]
 include::geometry/object-vehicle/vehicle-index.adoc[leveloffset=+3]
 include::geometry/object-human/human-index.adoc[leveloffset=+3]
 include::geometry/object-environment/environment-index.adoc[leveloffset=+3]