QGIS By Example by Bruy Alexander & Svidzinska Daria

Author:Bruy, Alexander & Svidzinska, Daria
Language: eng
Format: epub
Publisher: Packt Publishing
Published: 2015-06-28T16:00:00+00:00

In the previous steps, you defined some major options. As we need to create a raster with exactly the same extent and resolution as lidar_dem.tif, we will use advanced options by editing the gdal_rasterize command-line parameters: Click on the Edit button to make the line editable. All the previous options will be deactivated and grayed out.

Delete the –ts 3000 3000 option, as we are going to specify a resolution parameter that makes raster width and height parameters that are defined by –ts meaningless.

The –init 0 parameter defines the initial values of the output raster. It creates an empty raster with initially predefined values, and then vector values are burned into it. In our case, this means that building-free areas will be assigned zero values.

The target extent is defined by the –te parameter described by space-separated bounding box values (Xmin, Ymin, Xmax, and Ymax) in georeferenced units. If you want to use a predefined extent, just copy its values from a piece of correspondent raster metadata. Don't forget to replace the commas and semicolons with spaces.

The target resolution (–tr) parameter defines the vertical and horizontal pixel size in units specified by the layer's CRS.

The output data type is defined by the –ot parameter, whose default value is Float64, but we replace it by Float32, which is the same as that for lidar_dem.tif.

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