What is the correct color map format (.txt) for a color map I want to load in the Raster Layer Properties/Symbology menu of QGIS (v. 3.6.0)
[GIS] QGIS color map format
colormappingqgis
Related Solutions
I don't really know how you got the CSV color ramp so I can't perfectly answer but you should adopt the following couple of functions
layer.saveNamedStyle("your_raster_style.qml")
and imagining a layer1 raster file
layer1.loadNamedStyle("your_raster_style.qml")
Not need to manually copy the style IMO.
Interesting question, and one I've stumbled on myself but not found an answer to.
I haven't found any, not even in the extensive cpt-city catalog.. and ColorBrewer doesn't appear to have any either.
The ramp you describe makes sense to me, because :-
- opposite angles (180 degrees apart) on the HSV wheel are complementary colours.
- assuming your azimuths start at 0=north, not 0=east, it also gives a sense of illumination (lighter from the south, darker to the north)
- the hue ramp shows a continuous line
It works well for me - for example, when using this to colour an aspect raster.
However it doesn't work so well under colour-blindness simulation (QGIS allows you to preview the map as a deuteranope/protanope would). Here's what it looks like in one of the colour-blind modes. West and North, and East and South, are difficult to tell apart so it ends up looking a bit "two tone".
After a bit of trial and error I found a ramp which seems to work fairly well for both normal and colour-blind vision, based on your ramp, but working in RGB. The following .qml file has the details. You may need to edit this for versions older than 2.18.7, but you should be able to work out the ramp settings if you can't get this to load.
<!DOCTYPE qgis PUBLIC 'http://mrcc.com/qgis.dtd' 'SYSTEM'>
<qgis version="2.18.7" minimumScale="inf" maximumScale="1e+08" hasScaleBasedVisibilityFlag="0">
<pipe>
<rasterrenderer opacity="1" alphaBand="-1" classificationMax="360" classificationMinMaxOrigin="MinMaxFullExtentEstimated" band="1" classificationMin="0" type="singlebandpseudocolor">
<rasterTransparency/>
<rastershader>
<colorrampshader colorRampType="INTERPOLATED" clip="0">
<item alpha="255" value="0" label="0" color="#2250fe"/>
<item alpha="255" value="92.3" label="92.3" color="#00a83b"/>
<item alpha="255" value="181" label="181" color="#fdd248"/>
<item alpha="255" value="271" label="271" color="#b3507e"/>
<item alpha="255" value="360" label="360" color="#2250fe"/>
</colorrampshader>
</rastershader>
</rasterrenderer>
<brightnesscontrast brightness="0" contrast="0"/>
<huesaturation colorizeGreen="128" colorizeOn="0" colorizeRed="255" colorizeBlue="128" grayscaleMode="0" saturation="0" colorizeStrength="100"/>
<rasterresampler maxOversampling="2"/>
</pipe>
<blendMode>0</blendMode>
</qgis>
This makes the differences more visible for both normal and colour blind views. West and east are still a bit difficult to tell apart, but are more distinct than before.
Caveat: I'm not colour blind so I have no idea how accurate the simulation is :)
Best Answer
It looks like this:
and so on... Tip: just try it out by saving it to a text file and watch the differences.