[GIS] How to classify/style rasters correctly

classificationqgisraster

I am using a GeoTiff raster data and trying to classify it. I was wondering what are the techniques that I can use in QGIS to do this?

The raster I have looks like

enter image description here

but I tried the reclassify tool in ArcMap and it looks like this

enter image description here

Now I wish do the similar classification using QGIS and I was able to acheive it by adding 9 entries in the Generate new Color map and clicking classify and applying it to the map. The image looks like this,

enter image description here

I again tried going to the Transparent tab and found that the No data value is -3.4e+38 and then clicked on Apply. Nothing changed. I then selected the Band1 in the Transparent band and then applied and the entire map disappears. Is it possible if I can display it in the same manner as the ArcMap's output?

Best Answer

Try the following:

  1. Select the identify tab (an arrow with an "i")
  2. Select the black extent box to capture the value
  3. Right-click on your raster layer, select "properties"
  4. In the "Style" tab, select the color map you would like to display, select "Apply"
  5. Move to the "Transparency" tab and add the value you captured in step 2 to the "No Data Value" box and select "apply"

These steps will apply your settings to the layer properties only--they will not be permanent.

If you need to reclassify your raster into discrete steps, try using the raster calculator, here are two links to get you started: GIS.se & GIS.se2 . Also, check out the 1-band raster color table for a different color ramp.

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