Introduction

The concept of 'map' in OpenSimulator can refer to one of two things.

1. The minimap - this is the small map you see of the current and surrounding regions in the viewer. 2. The main map - This is the map you see when opening the main map window.

The minimap is generated purely by the viewer, and is decorated with an image of the terrain, the positions of other avatars on that region, objects colour coded by whether you own them, etc.

The main map is generated purely by OpenSimulator.

For the rest of this document we will talk about the main map, though more information can be inserted in the future about the minimap.

The main map

Linden Lab viewer 1 and associated TPVs, and Linden Lab viewer 2 and 3 and associated TPVs have different ways of receiving map data.

For viewer 1, maptiles were generated and stored in the asset service, with the asset UUID recorded in the regionMapTexture column in the regions table by the grid service. On opening the main map, the viewer would send a MapBlockRequest UDP message requesting the map blocks for a certain range. The simulator would interpret this message, fetch the appropriate map texture UUIDs by requesting the region information from the grid service (and parcel image if available, though we won't get into that here) and return them to the viewer. The viewer would then request the textures identified by the UUIDs as required.