#74 - Central African Republic: consolidated mapping, road network and places over low resolution areas of Bing imagery

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Getting a thematic, consolidated data over a territory is one of the main concerns for OSM, that often confronts very detailed areas and very partially mapped areas. The road network over Central African Republic is already quite detailed, but it is impacted by this lack of high resolution imagery everywhere over the country.

Indeed, the Bing imagery layer does not provide high definition imagery everywhere, and large areas are only covered by 30m pixel LandSat imagery that often allow to trace only rough road objects. Many localities are totally invisible on this imagery. Mapbox imagery can sometimes provides an alternative, but not everywhere.

This project uses imagery provided by Digital Globe Maps API and focus on areas of Bing low resolution imagery, using a reference buffered layer from the existing, rough OSM data. It is complementary to this TM project, that uses Bing imagery.

Created by SeverinGeo - Updated - Priority: medium

  Instructions

Entities to Map
primary, secondary, teritay and unclassified roads, residential landuse, localities with categories and names
Changeset Comment
CAR, road network improvements, residential areas and localities name
When saving your work, please leave the default comment but add what you actually mapped, for example "added buildings and a residential road".
Imagery

[imagery url available only after accepting the license]

Access to this imagery is limited by the Digital Globe Maps API license agreement.

You need to review and acknowledge the agreement.


This mapping project does not fit with iD. Please read the following instructions that provide the right tags to be used.

The aim is to map both the road network, the residential areas and add locality names, and add Digital Globe Maps API as a source. Unfortunately this imagery service does not provide the date of the imagery acquisition. This is why Bing remains the preferred imagery service rather than Digital Globe Maps API, wherever it provides high resolution imagery.

1) Select and lock a tile then load it as usual in JOSM. The Digital Globe Maps API will be automatically loaded.

2) Add the Bing layer to figure out where the high resolution cover ends. If not already done, cut the road at this location

3) The aim is going from one end to another and enhance the road if needed. Please work at a close scale: the scale bar should be under 50m. The best tool to improve the accuracy of a way is in JOSM and can be easily activated by pressing the "W" key. Then hold the "CTRL" key if you want to add new nodes.

4) If you cross a residential area that has not been traced yet, please trace it without being rough (see an example here and add the following tags:

  • landuse=residential and source=Digital Globe Maps API

5) If this residential area does not contain a place node yet, please add it in the approximate centre of the residential area. A hamlet holds until around 20 buildings, beyond it is a village. In order to get its name, you can use the GNS. To help you adding the GNS name, here is a .osm layer with the GNS data. You can switch between this layer and the OSM layer containing the data downloaded over the area. Please be careful only using the Geonames for populated place (it has the FC=PPL attribute) when giving a name to a locality, not names for hydrography (FC=H). If the place is in GNS, the node should have the following tags:

  • name=*, place=villageor place=hamlet, source=GNS;Digital Globe Maps API

If you cannot find the place in the GNS layer, the node should have the following tags:

  • fixme=name not in GNS, place=villageor place=hamlet, source=Digital Globe Maps API

6) When you reach the end of the Bing low resolution area (check by displaying the Bing imagery), cut the road at this location if not already done. If needed remove fixme=low accuracy or similar tags, and add the following tag (that will be used in the future by data users to filter the road network, this tag meaning that the road section is accurate) to the road section:

  • source=Digital Globe Maps API

7) Upload your changeset but please do not let the whole TMS address (that is not public!) address set as default by the Tasking Manager for the source, but replace it by the following tag:

  • source=Digital Globe Maps API;GNS or source=Digital Globe Maps APIif you did not use the Geonames

  Start contributing

Contributors Done Assigned