Make sure the input layer is your NLCD layer and the mask layer is the Voronoi polygon layer. Select the NLCD layer and choose Raster -> Extraction -> Clip Raster by Mask Layer. Finally, we are going to clip the NLCD data layer using this box.I was pulling my hair out for awhile trying to figure out how to do this seemingly simple task. By the way, if someone knows a simpler way to create a box in QGIS, please let me know. You should get a filled in box covering the area of interest. Ensure the text layer (bounding box points) is set as the input layer and hit Run. Then, select Vector -> Geometry Tools -> Voronoi Polygons from the menu bar. Make sure your text layer is selected in the layers list. Next, we need to create a filled-in polygon from these vertices.You should see the corners of the box appear around the region of interest (magenta in the image below). Check that the values have been separated properly into X and Y in the Sample Data box near the bottom and that the Geometry CRS is that of the project, EPSG:4326 - WGS 84. Make sure CSV (comma separated values) is selected for File Format. For file name, select the text file you just created. In the menu bar, select Layer -> Add Layer -> Delimited Text Layer.Create a text file with the corners of a box in a format like this: The other option is Raster -> Extraction -> Clip Raster By Mask Layer. The Raster -> Extraction -> Clip Raster byĮxtent option should work, but it complains about a negative width or height when I attempt it. Unfortunately, I haven't found an easy way to do this in QGIS. Now we need to clip the layer to the area of interest.I used the dataset labeled NLCD 2016 Land Cover (CONUS). TerraGear, command line version (compiled on Linux from the latest commit in the scenery/ws_2.0 branch, also the Windows version for one of the steps, which I'll explain later).Now let's get into the land cover creation process. Since this is the US and SRTM-1 elevation data is available, I used that. Before starting, you'll want to read the Using TerraGear wiki article:įor generating elevation data and airports, I'm using the process outlined in the wiki article. Combining that with osm2city could give some really nice, realistic looking scenery, maybe even good enough for VFR flight in some cases. After some googling, I came across the excellent work of wlbragg (Kansas and Ohio scenery) and realized the with the NLCD data, I could fix the coastlines while also getting a much more realistic representation of how the land actually looks. to a few places with osm2city, and I found that buildings and roads ended up in the water in a lot of places. The initial reason why I wanted to pursue this is because I was adding buildings, roads, pylons, etc. The land classes are only a rough approximation of the real types in a region, the detail is low, and the accuracy of coastlines is not very good. Why would you want to do this? Well, the default US scenery in FlightGear leaves a lot to be desired. I've had some good success, so I thought I would share my process and some sample results.įirst, the background. During the last several days I've been figuring out how the use QGIS to import data from the USGS National Land Cover Database for the US.
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