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Howto:Create custom terrain

3,313 bytes added, 21:21, 7 June 2019
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{{WIP}}'''Custom terrain''' in [[FlightGear]] is currently generated through processing shapefiles with [[TerraGear]]. In order to add custom scenery to FlightGear, you must create a custom shapefile.
Look [http://wwwA shapefile is a proprietary spatial information format.flightgearYou can edit them with almost every GIS package.org/forums/viewtopic.php?f=5&t=2147 here] an example QGIS is quite a good package for this type of the achievable resultproject.
Let's take Your goal for editing area data is to create a look at the Finistère in Brittany, Western France: if you click shapefile of a seamless layer of polygons which correspond to some type of land cover. This data is then fed into [http://mapserver.flightgear.org/map/?lon=-4.41840585539649&lat=48.4484146908477&zoom=11&layers=0B000000FTTFFFFFTFT|herethe mapserver], you will quickly see and understand how the Finistère county is know of [[FlightGear]]. Some towns/city (red), a few forests (green)possibly, etcTerraGear to create new scenery. Overall, it is not a very good resolution: a lot of angles, the detail level is not that good, some towns are missing. If you want a better definition on ground, there is some work to be done! The goal being to obtain something like this:
=== Evaluating the current data ===Before you begin, please make sure the area you want to improve doesn't already have good coverage. Just because it looks bad in FlightGear does not mean the area has not been improved. For this, you will need to check the Flightgear Mapserver, at [http://mapserver.flightgear.org/ mapserver.flightgear.org]. Let's take a look at the Finistère in Brittany, Western France: if you click [http://mapserver.flightgear.org/map/?lon=-4.41840585539649&lat=48.4484146908477&zoom=11&layers=0B000000FTTFFFFFTFT here], you will quickly see and understand how FlightGear interprets the data pertaining to Finistère county. Some towns/cities (red), a few forests (green), etc. Overall, it is not a very good resolution: a lot of angles, the detail level is not that good, some towns are missing. If you want a better definition on ground, there is some work to be done! The goal being to obtain something like this: #[http://mapserver.flightgear.org/map/?lon=13.40385&lat=52.50199&zoom=11&layers=000000BFFFFFFFFFTFFF B0000000TFFFTFFFTFFFFFFF Berlin]#[http://mapserver.flightgear.org/map/?lon=9.40368&lat=47.63699&zoom=11&layers=000000BFFFFFFFFFTFFF B0000000TFFFTFFFTFFFFFFF Bodensee surroundings]#[http://mapserver.flightgear.org/map/?lon=-88.55704&lat=43.98436&zoom=11&layers=000000BFFFFFFFFFTFFF B0000000TFFFTFFFTFFFFFFF Oshkosh surroundings]#[http://mapserver.flightgear.org/map/?lon=-62.87648&lat=17.69865&zoom=10&layers=000000BFFFFFFFFFTFFF CarribsB0000000TFFFTFFFTFFFFFFF Carribean Islands]
You will immediately notice the improvement to the ground. When flying, the difference is huge. Moreover, this enables the autogeneration of cities, trees, farmland, and so on.
[[File:C31e36f2a2cbb278a1603dfe2ba91193.media.395x288.png|thumb|200px|Landsat Map Search]]
[[File:1c9334d970963364b5ce1bc3a166a4fa.media.426x192.png|thumb|200px|Preview and download Landsat image]]
Browse to [http://glcfapp.umiacsglcf.umd.edu:8080/esdi/index.jsp the Earth Science Data Interface interface] to grab your [http://en.wikipedia.org/wiki/Landsat Landsat] data.
# Click ''Map Search''.
# Tick the ETM+ box (left column).
# Click on ''Update Map'' on the right bottom of the map.
# Click on the ''Place'' tab on the upper side of the map, in order to do a search by place, or you can do a search by latitude/longitude.
# In the Place field, type ''Amsterdam, Netherlands'' for instance.
# Now click the button with the mouse and the small + sign. This will allow you to select image tiles. Select all images that cover your area of interest, in our example this is just one image.
# Click on ''Preview and download''. This bring you to a selection page were you can choose what image you want to download. It is likely that there are pictures available from different dates for your area. Picking the most recent one is best, for known reasons.
# Clicking the ID will not bring you directly to the download page, first you have to click the ''Download'' button.
# Download the _nn80.tif.gz file (if this is not available, try an older image). Note that Landsat images are separated in different bands. Band 1/2/3/4/5/7 have 30m/Pixel resolution while band 8 (_nn80.tif.gz) has 15 meters per pixel.
# Uncompress the ''.tif.gz'' files in the directory of your choice.
[[File:QGIS_texel_4.png|thumb|200px|Tracing the small island.]]
[[File:QGIS_texel_5.png|thumb|200px|The finished small island polygon.]]
Using a GIS software gives you the opportunity to realize a full range of interesting operations: modification of VMAP map data, updates on the ground classification, etc...
* If you run GNU/QGIS Download for Linux, you can install QGIS with your usual package repositery manager; see [http:/OSX/www.qgis.org/en/download/binaries.html here]. The process is easy and not described here, but it is one the QGIS website.* If you are running Windows, download QGIS from [http://www.qgis.org/en/download/binariescurrent-software.html here] (Windows - Standalone).
The following is largely adapted from the [http://stattosoftware.com/flightgear/tutorial/index.html original QGIS scenery tutorial], which you may find of use.
# Launch QGIS.
# Click on <tt>Layer > Add a Raster layer</tt>.
# Modify the filter to search for *.tif files.
# Add the TIFF file you have just downloaded.
# Rightclick on the image in the layer sidebar and choose <tt>Set layer CRS</tt>, to select a projection model. This depends on the location of the area you're about to create. Look up your project's UTM coordinate through [http://upload.wikimedia.org/wikipedia/commons/e/ed/Utm-zones.jpg this image]. For Texel this is 31U, north of the equator, so we choose <tt>Projected Coordinate Systems > Universal Transverse Mercator (UTM) > WSG84 / UTM zone 31N</tt>. Locations south of the equator may need to use the 'N' zones as well. For example, the correct projection for Perth, Australia is <tt>Projected Coordinate Systems > Universal Transverse Mercator (UTM) > WSG84 / UTM zone 50N</tt>. Always select 'WGS84', as that is the globe model used in FlightGear. # Click on <tt>Layer > Add a new vector layerNew > New Shapefile Layer</tt> or on the corresponding icon. A dialog should pop up.#* Make sure the file type is an ESRI Shapefile. #* Make sure the vector type is set to polygon. #* # Click the 'specify CRS' button, to select a projection model. This must be the same as we did for the tiff background image.## You need to create a data column for this layer. Create a column new attribute called 'class'. Make sure it is a 'text data' (string ) column. Add it to the attribute list by selecting the Add Values Manually button. ## The 'OK' button should now be available for you to select. Select 'OK'. #* # There should be a dialog box prompting you to save your vector layer. Save it in your scenery directory with your GeoTIFF. (This is not required but significantly helps organization.) #* A projection box should pop up. Select 'WGS 1984'. After all, that is the globe model used in FlightGear.
# Your vector layer should appear in the left-hand toolbar. You are ready to begin digitizing.
#Select the newly created layer in the layer list, toggle editing (<tt>Layer > Toggle Editing</tt>) and finally select Capture Polygon from the same menu/toolbar.
# With your mouse, left-click on a point at the southwestern edge of the small island.
# We now want to trace the outline of the island. Move your mouse to another point below the first point and click it again. Your mouse should show a red line. The points should not be redundant - for instance, as long as the line between two points is straight, there is no need for another point in between the two.
# 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].
We have been working Continue with UTM coordinates so far. To generate scenery that can be used in FlightGear we need to convert tracing all shapes on the shapefiles to the latitude/longitude formatisland: towns, industrial areas, grass, farmland etc.
* '''Windows'''
*# Download [http://www.forestpal.com/fgis.html fGIS] and install it as described.
*# Open an empty project and visit <tt>Utilities > Shapefile Projection Utility</tt>.
*# Look up your projects UTM coordinate through [http://upload.wikimedia.org/wikipedia/commons/e/ed/Utm-zones.jpg this image]. For Texel this is 31U, so we choose UTM31 in fGIS. If your project is located south of the equator, you tick the S box.
*# Set the Output Shapefile Project to <tt>Lat./Lon.</tt>.
*# Now click the Input Shapefile button to load the shapefile that we exported from qGIS.
*# Using the Output Shapefile button we decide where we want to store the lat/lon shapefile. This has to be a non-exisiting file, so remove before updating.
*# Click the Convert button.
===Snapping===It is very important to enable "snapping" now. Snapping means each polygon will fit together nicely, like a jigsaw puzzle. If snapping is not enabled, the polygons will not form a continuous layer, which has a number of different problems. 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 > Snapping Options</tt>.# 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, while a bigger value makes it easier to snap when zoomed out.# Click OK to save the snapping options. ==== Distinguishing Land Class Types from LANDSAT data ====You may Google Maps or Yahoo Maps running alongside your program to see what is what on the black/white image, but most areas are recognizable without use of the software. If you need help determining what part of the black-and-white image, please currently refer to the [http://stattosoftware.com/flightgear/tutorial/index.html#distinguishing original Stattosoftware Scenery Tutorial]. Instead of determining in a single band image you can also combine different ETM+ bands in a RGB file. Some information about different band combinations can be found here [http://web.pdx.edu/~emch/ip1/bandcombinations.html]. === Exporting the shapefile ===In order to turn the landclass into scenery we have to split it into seperate shapefiles for each landclass.  # Open the Attribute table (<tt>Layer > Open Attribute Table</tt>).# Type "Sand" (or another class) into the search box and press the Search button. This will select all polygons that have the Sand class assigned.# Go to <tt>Layer > Save Selection as vector file</tt> and save the sand shapefile somewhere on your computer.# Do the same for all other classes.# To make the difference between land and sea (landmass) we save the entiry shapefile (<tt>Layer > Save as...</tt>, ESRI Shapefile). If you want to see these shapefiles integrated into the Custom Scenery database you can contact papillon81 and statto (through IRC or Forum). Please be remembered that your data has to be derived from freely available (public domain) sources. Other material can not be integrated due to legal issues. ===Generating scenery===
Please continue with [[TerraGear]] to generate the landclass into useable scenery.
== External links ==
{{forum|5|scenery enhancement}}
* [http://www.custom-scenery.org Terragear-cs website]
* [http://wiki.qgis.org QGIS Wiki]
* [http://www.flightgear.org/forums/viewforum.php?f=5 Dedicated FlightGear forums for scenery enhancement]
* [http://wiki.osgeo.org/wiki/LandcoverDB_CS_Detail OSGEO Wiki]
* {{forum link|t=5566|text=Editing shapefiles for inclussion in official scenery}} (forum topic)
 
=== Resources ===
* [http://stattosoftware.com/flightgear/tutorial/index.html Tutorial by John Holden]
[[Category:Howto|Using QGIS and satellite pictures]][[Category:Scenery enhancement|Using QGIS and satellite pictures]]
[[fr:Howto: Utilisé Utiliser QGIS et images satellites]]

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