#591 - South Sudan Crisis, Cholera outbreak in Juba, mapping with WorldView-2 imagery (Archived)

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This project was archived.

  • Author: HOT, MapGive
  • Mapping for: All the humanitarian stakeholders
  • Purpose: Crisis Response
  • Priority: High

Context

Juba, the capital city of South Sudan, has experienced rapid growth in the last few years, and following the violence since December 2013, is now facing a cholera outbreak, as shown on this overview map from UNOCHA or this more detailed map from the UN WASH cluster. This urges the need for updated foundation geographic data. Thanks to the MapGive project, we have access to a WorldView-2 imagery dated 20 February 2014, whose offsets have been corrected in this TM job.

EDIT: after this job has been published, the Bing imagery has been renewed and is now dated 20 June 2013. The mapping process mixes the two.

Imagery Details

The imagery downloaded with the job is from Digital Globe’s WorldView-2 satellite taken on February 20, 2014. The image is almost 10GB in size and has been pan-sharpened (combined panchromatic and multispectral images) for visual clarity and orthorectified for terrain corrected geographic precision (CE90=8.4; RMSE=3.9). A second rectification process was performed to reduce offset between the image and the Bing Imagery / existing OSM data. Additionally, the image has been contrast stretched using a custom stretch and processed into a Tiled Map Service (TMS) for performance.

With the renewal of Bing imagery (now dated dated 20 June 2013), the offsets with the Bing imagery informed with the JOSM offset_db plug-in are now obsolete and it is not worth to use them. See the instructions tab.

MapGive

Through the MapGive project, the Humanitarian Information Unit (HIU) of the U.S. Department of State is providing the OpenStreetMap community access to updated satellite imagery services to help assist with humanitarian mapping.

Created by sev_osm - Updated - Priority: low

  Instructions

Entities to Map
roads, streets, buildings, walls, water streams and canals
Changeset Comment
South Sudan, Juba, #hotosm-task-591
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 NextView license agreement.

You need to review and acknowledge the agreement.


You can find a model task here.

  • Check in the vector data is correctly aligned on Bing imagery, that is the reference for the georeferencing. Move/redraw the data if necessary.

  • Map any missing entity to map. Please trace ALL individual buildings and tag it as building=yes. Please SQUARE THE RECTANGULAR BUILDINGS if you do not use a mapping tool that does it automatically. With iD, you just need to click on the building once drawn and then a few icons show up as extra tools, and there is a square icon to square buildings. you can also type 'S' as a shortcut. Same thing for round buildings: there is an icon and the shortcut is 'O, to get perfect circles. For clusters of building, DO NOT enclose the whole area as one building. It is important to trace individual structures for future damage analysis.

  • Align manually the WordView-2 imagery on the vector data (and not the contrary). Modify/add anything that changed during the 8 months between the two imagery. Mostly there a few new buildings here and there within the residential area, and more new buildings on the edge of the city.

If you want to have an idea about what Juba looks like in the ground, you can watch this video for example.

  Start contributing

Contributors Done Assigned