Digitizing North East Unguja Island and Stone Town on Zanzibar

Between August 8^th and September 5^th, Spatial Collective held a series of workshops at the Commission for Lands (COLA) on Zanzibar. The aims of the workshops were to train and supervise the digitization of the UAV imagery in order to create a series of detailed spatial data layers while at the same time build capacity of the Commission for Lands (COLA) and the State University of Zanzibar (SUZA) staff in QGIS.

Specifically, the objectives of the workshops were:

1. Leverage the emerging data communities in Zanzibar and transfer knowledge and skills to local government officials and university staff, specifically the skills of project management and execution of digitization of drone imagery.
2. Produce a building footprint dataset of the pilot areas that demonstrate high quality agreed upon by the stakeholders and that follows the coding convention put forth by the Client.

To achieve objective 1, the following workshops were held with 12 participants (10 from COLA and 2 from SUZA):

Week 1 (August 14 – August 18):

• Introduction into project background, expectations, technology used, expected outputs and timelines
• Workshop on QGIS basics
• Workshop on data taxonomy
• Workshop on digitizing rules
• Workshop on quality control
• Setting up the digitizing environment in QGIS
• Start of digitizing both Stone Town and North East areas
• Start of manual error detection
• Fixing of errors

Week 2 (August 21 – August 25):

• All the buildings in the pilot areas digitized
• Write a script for automatic allocation of Building Reference Numbers
• Workshop on error types and error detection
• Workshop on checking layer for error detection
• Workshop on creating a database through QGIS
• Expansion of digitizing outside the pilot areas

Week 3 (August 28 – September 1):

• Cleaned the pilot area dataset based on feedback from stakeholders
• Workshop on setting up the Spatialite database
• Workshop on managing the database (downloading, uploading, saving)
• Lecture on characteristics of spatial data
• Workshop on data cleaning
• Workshop on Edge Matching
• Preparation of tailored manuals and guidelines

Week 4 (September 4 – September 6):

• Final handover of data and manuals

To achieve objective 2, the following datasets were produced:

• All the structures within the 19 grids of the North Eastern pilot area were digitized
• All the structures within Stone Town were digitized
• Altogether 18,911 buildings were digitized (16,338 in NE Unguja and 2,573 in Stone Town)
• The following attributes were assigned to each building:
  • Building condition (Complete, Incomplete, Foundation)
  • Problematic Capture for buildings which attribution or digitization was problematic
  • Change-set (date)
  • Building Area (square meters)
  • Unique Building Reference Numbers assigned to each building