Add documentation for StreamingUpdate

- Align figure
- Add architecture information
- Add section to top-level interface

Signed-off-by: Thomas Sedlmayer <tsedlmayer@pmsfit.de>

Author: thomassedlmayer

doc/architecture/architecture_overview.adoc

@@ -32,14 +32,16 @@ The following figure shows a more advanced use case for traffic participants.
 .Traffic participant with sensor models, AD function, and dynamic model
 image::{images_open_simulation_interface}/osi-traffic-participant-advanced.png[1100]
 
-[#fig-interface-streaming]
-.Interface for Streaming
-image::{images_open_simulation_interface}/osi-streaming-principle.png[1100]
-
 The `HostVehicleData` interface describes the measured internal states of a traffic participant.
 OSI currently provides only limited support for data structures that describe measured internal states of traffic participants.
 One example would be the `MotionRequest` interface that can be used to communicate the results of the behavior planning to the dynamic model.
 
+The `StreamingUpdate` interface enables partial ground truth updates to modules that favor performance, especially latency, over data completeness/consistency (e.g. visualization applications) or that do not require complete data in the first place (e.g. logging applications).
+
+[#fig-interface-streaming]
+.Interface for partial ground truth updates
+image::{images_open_simulation_interface}/osi-streaming-principle.png[1100]
+
 NOTE: OSI uses singular instead of plural for `repeated` field names.
 
 NOTE: All fields in an interface are set to `optional`.

doc/architecture/streaming_update.adoc

@@ -0,0 +1,10 @@
+ifndef::include-only-once[]
+:root-path: ../
+include::{root-path}_config.adoc[]
+endif::[]
+= Streaming update
+
+The `StreamingUpdate` message provides an interface to transmit a subset of ground truth and/or vehicle internal data.
+This interface mainly addresses applications with low latency requirements and no need for highly consistent and complete data, e.g. visualization applications.
+Static and/or non-relevant objects can be omitted as required for the specific use case.
+Note that the receiver of partial updates can only rely on the most up-to-date information at the corresponding timestamp. E.g. omitting objects does not indicate static behaviour but it may be sufficient for the use case to update certain objects at a later point in time.

doc/images/osi-streaming-principle.PNG

@@ -29,6 +29,8 @@ include::./architecture/motion_request.adoc[leveloffset=+3]
 
 include::./architecture/traffic_update.adoc[leveloffset=+3]
 
+include::./architecture/streaming_update.adoc[leveloffset=+3]
+
 === Model types
 
 include::./architecture/environmental_effect_model.adoc[leveloffset=+3]