How to Use and Import Shapefiles in WASDI

Shapefiles are used in WASDI to define Areas of Interest (AOI), mask regions, and customize geospatial processing workflows. This guide provides an overview of shapefile usage and instructions on how to upload them in WASDI.

Prerequisites

To import a shapefile you need:

  • a valid WASDI Account

  • a workspace

  • a shapefile

You can use QGIS for instance to prepare your (polygon) shapefile. If you need guidance, refer to the YouTube tutorial here.

Uses of Shapefiles in WASDI

Shapefiles play an important role in geospatial processing within WASDI. Some of their main applications include:

  • Defining Areas of Interest (AOI): Users can upload shapefiles to specify a geographic region for satellite image processing, reducing unnecessary computations outside the area of interest.

  • Masking and Filtering Data: Shapefiles allow masking of certain areas, such as water bodies or urban areas, to focus processing on relevant regions.

  • Customizing Processing Workflows: Many processing workflows, such as flood detection, can use shapefiles to refine results.

Here is an example of a Shapefile being used in the workflow of the SAR Archive Generator:

  • The Shapefile Mask parameter (JSON: “SHAPEFILEMASK”) allows uploading a shapefile (containing only one polygon) to exclude Sentinel-1 images outside the shapefile boundary.

  • The Area of Interest (AOI) must be rectangular, and the mask will exclude images outside the polygon.

  • This helps reduce unnecessary image processing while keeping relevant images for analysis.

../_images/example_AOI_shp.png

Example of image (in dark orange) within a rectangular AoI (blue shade) but outside the borders of the country of interest (Pakistan in this specific example).

Recipe

To add a shapefile in WASDI, follow these steps:

  1. Prepare the Shapefile: - A shapefile consists of multiple files, including:

    • .shp (feature geometry)

    • .shx (index of feature geometry)

    • .dbf (attribute information)

    • .prj (coordinate system and projection information in well-known text, or WKT, format)

    • .cpg (character encoding information) (Optional)

    • Ensure all required files are present in a single directory.

  2. Compress the Shapefile into a .zip File: - Select all necessary files (.shp, .shx, .dbf, .prj, and optionally .cpg). - Right-click and choose “Send to” > “Compressed (zipped) folder” (on Windows) or use a similar method on other operating systems. - The name of the .zip file should match the shapefile name (e.g., if your files are named Valencia_AOI.shp, Valencia_AOI.shx, Valencia_AOI.dbf, and Valencia_AOI.prj, the zip file must be Valencia_AOI.zip). - Do not place the files inside a folder before zipping; the files should be directly in the .zip archive.

  3. Upload the Shapefile to a Workspace in WASDI: - Navigate to your required Workspace in WASDI. - Click on the Import button from the tools section. - Select and upload the shapefile .zip archive from your local directory.

  4. Visualizing the Shapefile: - Expand the uploaded shapefile from the workspace. - Expand the Bands of the shapefile. - Publish the band to overlay it on the satellite imagery in the workspace.

../_images/example_Tillaberi_shp.png

Example of a shapefile (in dark grey) published in WASDI, highlighting a region in Niger.

Conclusion

Shapefiles are a very useful tool in WASDI. By following the steps above, users can efficiently upload and utilize shapefiles to improve the accuracy and relevance of their workflows.