1

I have downloaded VIIRS day/night Band data from here but when I try to open tiff files in QGIS software, it doesn't show like usual night light files and it is similar to cloudy sky image (see the screen shot below).

What should I do to open and see it truly ?

enter image description here

2

You are seeing it truly. The image is a single-band raster, so there is no color, just a gradation of values from low to high (dark to light), which you are seeing as grayscale.

To make the image appear like the typical Night Light image products you're familiar with, you'll need to create/assign an appropriate color ramp to the imagery so that the symbology matches what you're expecting.

enter image description here

Below is a quick first-pass color ramp that gives me acceptably similar results:

<!DOCTYPE qgis_style>
<qgis_style version="2">
  <symbols/>
  <colorramps>
    <colorramp type="gradient" name="NOAA VIIRS" tags="Colorful">
      <prop k="color1" v="0,0,0,255"/>
      <prop k="color2" v="255,255,255,255"/>
      <prop k="discrete" v="0"/>
      <prop k="rampType" v="gradient"/>
      <prop k="stops" v="0.333;0,0,96,255:0.666;255,218,104,255"/>
    </colorramp>
  </colorramps>
  <textformats/>
  <labelsettings/>
</qgis_style>
  • I think the problem is for stretch settings. When I asked from Earth Observation Group, they told me to use the file with "avg_rade9" extension and correct stretch setting. But I don't know the correct stretch so I just changed the min and max to 0 and 9 and the map became like usual night light maps. but what is the correct stretch setting ? – Sina Alvandi Oct 26 at 5:46
  • I used 0-32 to get the level of contrast I wanted. Look at the histogram to be certain. – Saijin_Naib Oct 27 at 6:16

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