Heading for map control

[rjksmith]

Background

Many modern web map APIs support map rotation where the upward direction of the map display need not point north.

Issue

Web maps improve understanding of geotagged video by providing geospatial context for the footage:

1. Objects observed in video can be identified more easily from map data.
2. Map data be used to search for video observations more efficiently.

Enabling a map display to match the heading of video footage could make geospatial data quicker and simpler to understand. For example, car sat navs typically display the road ahead from the driver's perspective so users can easily understand whether to turn left or right.

Discussion

A demo was presented to OGC Testbed-20 GIMI meeting on 19 September 2024 showing how web map heading can be matched with geotagged video perspective in a browser to display information in an intuitive way.

This feature should degrade gracefully for web map APIs that do not support map rotation. An error message should not be generated when map rotation is not supported, though a warning message could optionally be issued.

This discussion is specific to heading for map control commands, though is related to issue #11.

Proposal

Add heading in degrees to map control commands.

WEBVMT

NOTE Set initial map heading to 123.4

MAP
lat: 12.345678 lng: -1.234567
rad: 1234.5
hdg: 123.4

NOTE Change map heading to 234.5

12:34:56.789 -->
{"pan-to": {"lat": 23.456789, "lng": -2.345678, "hdg": 234.5}}