Howto:Create custom terrain: Difference between revisions

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Howto:Create custom terrain (view source)

Revision as of 12:16, 15 November 2009

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# Click ''Map Search''.
# Click ''Map Search''.
# Click ETM+ (left column).
# Tick the ETM+ box (left column).
# Click on ''Update Map'' on the right bottom  of the map.
# 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.
# 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 ''Brest, France'' for instance.
# In the Place field, type ''Amsterdam, Netherlands'' for instance.
# Check that you have ''2 images in selection'' for example : this confirms that your selection is good. For Brest, there are two Landsat pictures to cover the area.
# 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''. You will get the screen shown on the right. On the left you can check the picture you are going to download. The size of the pictures is also given.
# 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.  
# Click on ''Download'' to get a FTP access.
# Clicking the ID will not bring you directly to the download page, first you have to click the ''Download'' button.
# Only the files with a ''.tif.gz'' and ''.met'' extensions are of interest.
# Download the _nn80.tif.gz file (if this is not available, try an older image).
# Uncompress the ''.tif.gz'' files in the directory of your choice.
# Uncompress the ''.tif.gz'' files in the directory of your choice.


=== Working with QGIS ===
=== Working with QGIS ===
[[File:Capture-4.png|thumb|200px|QGIS with the TIFF image.]]
[[File:QGIS_texel_1.png|thumb|200px|QGIS with the TIFF image.]]
[[File:Capture-7.png|thumb|200px|Creating the class column.]]
[[File:QGIS_texel_2.png|thumb|200px|Creating the class column.]]
[[File:Capture-10.png|thumb|200px|Toggle editing]]
[[File:QGIS_texel_3.png|thumb|200px|Toggle editing.]]
[[File:Capture-12.png|thumb|200px|Tracing the island.]]
[[File:QGIS_texel_4.png|thumb|200px|Tracing the small island.]]
[[File:Capture-13.png|thumb|200px|The finished island polygon.]]
[[File:QGIS_texel_5.png|thumb|200px|The finished small island polygon.]]
[[File:Capture-15.png|thumb|200px]]
[[File:Capture-17.png|thumb|200px]]
Using a GIS software gives you the opportunity to realize a full range of interesting operations: modification of VMAP data, updates on the ground classification, etc...
Using a GIS software gives you the opportunity to realize a full range of interesting operations: modification of VMAP data, updates on the ground classification, etc...


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# Your vector layer should appear in the left-hand toolbar. You are ready to begin digitizing.
# 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.
#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 island.
# 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 above 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.
# 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.
# You will want to digitize features in a circular manner to avoid problems. You can always go back and add points later. With this in mind, move your mouse to a third point on the island. A small triangle should form, representing the polygon which would result if you decided you were done with the polygon.  
# You will want to digitize features in a circular manner to avoid problems. You can always go back and add points later. With this in mind, move your mouse to a third point on the island. A small triangle should form, representing the polygon which would result if you decided you were done with the polygon.  
# Continue outlining the island by clicking along its shoreline, initially moving to the right. When you are on your last point, instead of left-clicking, right-click. QGIS will finish the polygon.  
# 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 an island, covered with grass, type in ''GrassCover''. 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].
# 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].


===Generating scenery===
===Generating scenery===
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