Convert Raster to Polygon. by this method you can Extract basin boundaries from a digital elevation model (DEM) is a fundamental step in hydrological
Convert Raster to Polygon. by this method you can Extract basin boundaries from a digital elevation model (DEM) is a fundamental step in hydrological modeling and watershed analysis. In this detailed guide, you'll learn how to convert a raster basin into a polygon shapefile using common GIS tools like QGIS or ArcGIS. Whether you're working on catchment delineation or just need a clean vector output from your DEM data, this tutorial walks you through the entire process.
🎥 Video Tutorial : Ratser To Polygon
Watch the tutorial on YouTube
Why Convert Raster to Polygon?
Raster data is great for representing elevation and flow direction, but when it comes to using your basin as a boundary for overlay analysis, shapefiles are far more versatile. By converting your raster basin into a polygon:
- You can clip other layers to the basin
- Perform zonal statistics with ease
- Create clean cartographic outputs
- Integrate boundaries into modeling software
Step-by-Step Workflow
- Open your DEM-derived basin raster in QGIS or ArcGIS.
- Reclassify the raster to binary: set basin pixels to
1, and everything outside the basin to0. - Use the “Raster to Polygon” tool to convert the binary raster into a vector polygon layer.
- Inspect the output polygons and delete any unwanted shapes outside the main basin.
- Save your cleaned polygon as a shapefile (*.shp) for future use.
Common Problems Solved in This Tutorial
- Multiple polygon fragments after conversion
- Unwanted noise or false boundaries
- Confusion about how to reclassify raster values correctly
- Misuse of conversion tools that cause incomplete vector shapes
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For more advanced GIS workflows and data tools, visit gis.geojamal.com.
