Howto:Create custom terrain: Difference between revisions

Howto:Create custom terrain (view source)

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 # Continue outlining the island by clicking along its shoreline. When you are on your last point, instead of left-clicking, right-click. QGIS will finish the polygon.
 # A dialog box will pop up, asking you to type in the value for 'class'. Since this is a shoal, existing of just sand, type in ''Sand''. This step is important - it is how you know what each polygon should be mapped to in our finished scenery. A list of "allowed" materials (and thus classes) is available [http://wiki.osgeo.org/wiki/LandcoverDB_CS_Detail here].
+Continue with tracing all shapes on the island: towns, industrial areas, grass, farmland etc.
+It is imporant to enable "snaping" now. We don't want small holes in our scenery, nor do we want overlapping polygons. Snapping adjusts each point as you go by - you will miss occasionally and have to correct it - so you don't have to worry about lining the polygons up precisely.
+# Open <tt>Settings > Project Properties</tt> and click the Snapping options... button.
+# Click the tickbox(es) in front of your layer(s) and set Tolerance to 20 (map units). A smaller tolerance will make it easier to work with very small and detailed layers.
+# Click OK to save the snapping options.
+====Distinguishing Land Class Types from LANDSAT data====
+For people who have not worked with satellite imagery before, it may be difficult to figure out what certain areas of land are. Of course you need Google Maps or similair software running, to see what is what on the black/white image, but most areas can be recognised without. Here is a list which may help you:
+* '''Water''' is always black or very close to being black. However, shadows from clouds can also appear black on your image. If your image has clouds, use caution!
+* '''Forests''' are also dark grey.
+* '''Scrub Cover''' is like a forest, but lighter in color since the forest consists of shrubs, not trees.
+* '''Crops''' can be a wide variety of different colors, but are easily distinguishable by their field-like patterns. You have your choice between dry crops, mixed crops and irrigated crops - take a look at the corresponding texture to figure out which crop style best suits your area.
+* '''Golf Courses''' should be digitized as a class even though we do not have a texture for them yet. They should be conspicuous by their pattern and their bright pixels.
+* '''Urban Areas''' should have some semblance of a pattern to them. Pixels can vary from darkness to lightness.
+* '''Towns''' are much smaller than urban areas and you may not be able to pick up any distinct patterns.
+* '''Industrial Areas''' should be digitized if you know where the areas are. They are usually characterized by large, boxy buildings on the outskirts of urban areas, though this obviously varies by city!
 We have been working with UTM coordinates so far. To generate scenery that can be used in FlightGear we need to convert the shapefiles to the latitude/longitude format.