You already have a GIS file loaded in QGIS, we will now apply to it some nice colors, then output a PNG background for our area of interest and final map.
The topographic GIS data you downloaded is by default displayed using a monochromatic palette (mapcolors) going from white to black; however, you have the option of using other colors. You can either load an existing mapcolor file, edit an existing mapcolor file or create your own mapcolors. To do this, you will need to edit the layer's properties.
Please note that per the Wikipedia map conventions, you should use the colors provided for all topographical shading.
The QGis mapcolor files page already has some palettes you can copy, save as .qml, and use.
Copy-paste the following color code in an empty, plain text document (using something like Notepad or TextEdit), then save it in ./QGis/Mapcolors/ as Wikicarto_2.0.qml (the palette's name + .qml). We will frequently use it later.
Colormap "Wikicarto_2.0.qml"
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<!DOCTYPE qgis PUBLIC 'http://mrcc.com/qgis.dtd' 'SYSTEM'> <qgis version="1.6.0-Copiapo" minimumScale="1" maximumScale="1e+08" hasScaleBasedVisibilityFlag="0"> <transparencyLevelInt>255</transparencyLevelInt> <rasterproperties> <mDrawingStyle>SingleBandPseudoColor</mDrawingStyle> <mColorShadingAlgorithm>ColorRampShader</mColorShadingAlgorithm> <mInvertColor boolean="false"/> <mRedBandName>Not Set</mRedBandName> <mGreenBandName>Not Set</mGreenBandName> <mBlueBandName>Not Set</mBlueBandName> <mGrayBandName>Bande 1</mGrayBandName> <mStandardDeviations>0</mStandardDeviations> <mUserDefinedRGBMinimumMaximum boolean="false"/> <mRGBMinimumMaximumEstimated boolean="true"/> <mUserDefinedGrayMinimumMaximum boolean="false"/> <mGrayMinimumMaximumEstimated boolean="true"/> <mContrastEnhancementAlgorithm>StretchToMinimumMaximum</mContrastEnhancementAlgorithm> <contrastEnhancementMinMaxValues> <minMaxEntry> <min>-10458</min> <max>6741</max> </minMaxEntry> </contrastEnhancementMinMaxValues> <mNoDataValue mValidNoDataValue="false">-9999.000000</mNoDataValue> <customColorRamp> <colorRampType>DISCRETE</colorRampType> <colorRampEntry red="245" value="8000.000000" green="244" blue="242" label="altitude 19 neiges eternelles"/> <colorRampEntry red="224" value="7000.000000" green="222" blue="216" label="altitude 18 neiges eternelles"/> <colorRampEntry red="202" value="6000.000000" green="195" blue="184" label="altitude 17 neiges eternelles"/> <colorRampEntry red="186" value="5000.000000" green="174" blue="154" label="altitude 16 neiges eternelles"/> <colorRampEntry red="172" value="4000.000000" green="154" blue="124" label="altitude 15 neiges eternelles"/> <colorRampEntry red="170" value="3000.000000" green="135" blue="83" label="altitude 14"/> <colorRampEntry red="185" value="2000.000000" green="152" blue="90" label="altitude 13"/> <colorRampEntry red="195" value="1500.000000" green="167" blue="107" label="altitude 12"/> <colorRampEntry red="202" value="1000.000000" green="185" blue="130" label="altitude 11"/> <colorRampEntry red="211" value="800.000000" green="202" blue="157" label="altitude 10"/> <colorRampEntry red="222" value="600.000000" green="214" blue="163" label="altitude 9"/> <colorRampEntry red="232" value="400.000000" green="225" blue="182" label="altitude 8"/> <colorRampEntry red="239" value="300.000000" green="235" blue="192" label="altitude 7"/> <colorRampEntry red="225" value="200.000000" green="228" blue="181" label="altitude 6"/> <colorRampEntry red="209" value="150.000000" green="215" blue="171" label="altitude 5"/> <colorRampEntry red="189" value="100.000000" green="204" blue="150" label="altitude 4"/> <colorRampEntry red="168" value="50.000000" green="198" blue="143" label="altitude 3"/> <colorRampEntry red="148" value="20.000000" green="191" blue="139" label="altitude 2"/> <colorRampEntry red="172" value="1.000000" green="208" blue="165" label="altitude 1"/> <!-- <colorRampEntry red="167" value="0.000000" green="223" blue="210" label="depression"/> --> <colorRampEntry red="216" value="0.000000" green="242" blue="254" label="altitude -1"/> <colorRampEntry red="198" value="-20.000000" green="236" blue="255" label="altitude -2"/> <colorRampEntry red="185" value="-50.000000" green="227" blue="255" label="altitude -3"/> <colorRampEntry red="172" value="-100.000000" green="219" blue="251" label="altitude -4"/> <colorRampEntry red="161" value="-250.000000" green="210" blue="247" label="altitude -5"/> <colorRampEntry red="150" value="-500.000000" green="201" blue="240" label="altitude -6"/> <colorRampEntry red="141" value="-750.000000" green="193" blue="234" label="altitude -7"/> <colorRampEntry red="132" value="-1000.000000" green="185" blue="227" label="altitude -8"/> <colorRampEntry red="121" value="-2000.000000" green="178" blue="222" label="altitude -9"/> <colorRampEntry red="113" value="-4000.000000" green="171" blue="216" label="altitude -10"/> </customColorRamp> </rasterproperties> </qgis> |
More are available there.
For this, you will be using the Wikicarto_2.0.qml file you created earlier in this tutorial.
If you would like to edit already loaded mapcolors, simply go to the Colormap tab. There, you can add or delete entries by selecting them and clicking the appropriate buttons. You can also edit the Value, Color, and Label fields of any entry by simply double clicking on the field you wish to change. Click Apply to see the changes.
If you would like to create your own colors from scratch—this is advised against for topographical maps, which should follow the map conventions— you can do so by following these steps on a layer which has not had colors loaded onto it:
You can save edited or created mapcolors as a style file by clicking Save Style... at the bottom of the Layer Properties window. This will allow you to apply those mapcolors to another map. If you would like to make colors—whether loaded or created—the default colors for the map, click Save As Default. This will allow you to keep editing or loading different colors while having the option to Restore Default Style if you don't like the changes you've made.
The most convenient way to output a high quality topographic background is to use the SimpleSVG plugin.
Most plugin are in the repositories.
Our important plugins: Shaded relief ; SimpleSvg, Raster Terrain Analysis (under test), OpenLayer (under test).
Extended content
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:This section is about adding a plugin not available through QGis (1.7) > Plugins > Fetch plugins, and thus to install handily. We take the case of QGis SimpleSVG plugin.
SimpleSVG currently save the QGis' screen as a SVG with the correct layer division. This save us a lot a energy for later Inkscape work, especially colorations. SimpleSVG is a plugin currently under developement, Richard Duivenvoorde is looking for ideas for improvement. |
You are now working with QGis, your GIS data—namely, ETOPO1—and your customized palette. To output your first topographic background, don't use File > Save as Image, which is a simple screenshot. For better quality, use the SimpleSVG plugin.
Install the QGIS plugin named "SVGsimple" from the QGIS repository then you can export GIS layers, with both SVG and raster layers, and with a cleanly coded SVG file and its associated bitmap background.
SVGsimple doesn't natively know which information should be used to name each group or vector item. You have to tell it:
SVGsimple will remember the field 'Name' and names the GIS items as such in the SVG. In example the GIS item with the field 'name' being 'Amazon river' in QGIS will now become the .xml/.svg item 'Amazon river' in Inkscape.
An clean .svg file and .png background are produced, thus providing both the raster and vector layers.
It is now up to you and Inkscape to change the style of each svg group / item, and to add further content (icons, labels, legend, etc.)
→ waiting for a volunteer
Concept: Use an elevation GIS file, a discrete black & white colormap, and the Print composer to output one 1500px/1500px black & white png for each altitude (0m, +200m, +500m, etc, name the png accordingly!). This by a cycle such as 1. editing the map color, 2. actualizing the Print composer, 3. outputting the new png. Then use Inkscape to vectorize : load all png, align them, vectorize each using 2 colors + delete background. Color each vector polygon level (0m, 200m, ...) as need.
QGis can convert raster polygons into vector polygons (raster > polygonizer). It does contours too, which have no fill, and so you must use vector > geometry > lines to polygons in order to fill them up.
The table above has links to various tutorials and resources which can help in the creation of Wikipedia maps from digital georeferenced data (GIS).