{"id":1657,"date":"2015-08-27T03:04:13","date_gmt":"2015-08-27T03:04:13","guid":{"rendered":"https:\/\/grindgis.com\/?p=1657"},"modified":"2017-05-25T04:52:22","modified_gmt":"2017-05-25T04:52:22","slug":"raster-overlay-analysis-qgis","status":"publish","type":"post","link":"https:\/\/grindgis.com\/?p=1657","title":{"rendered":"Weighted Sum Raster Overlay Analysis using QGIS"},"content":{"rendered":"

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In this tutorial I\u00a0will talk\u00a0about the weighted sum overlay analysis in QGIS<\/a>. Weighted sum overlay is usually done for the suitability analysis. It uses\u00a0several weighted raster layers for the\u00a0calculation. GIS uses Boolean logic to perform overlay analysis. This means it\u00a0uses conditional statements on input layers to generate suitability map.<\/p>\n

For each input layer\u00a0we have to assign the weight value. This weight value is multiplied to the input layer. Then\u00a0you have to sum\u00a0all these weighted layers to generate the final output map. \u00a0Let me give you simple example to identify the soil erosion potential area. The inputs are\u00a0terrain slope angle and vegetated\/not vegetated area. Result will be calculated as \u201cif slope >5% and vegetation=No” then erosion potential = true.<\/p>\n

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Here we are using weighted overlay analysis to find out ground water potential zones in a river basin using open source QGIS software. Usually this kind of analysis is done using ArcGIS. Unlike ArcGIS, QGIS have certain limitations but still we can do the raster overlay analysis. The inputs are\u00a0as follows:<\/p>\n

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