I would like to set a raster transparency to represent its elevation, so that the mountain tops are opaque and gradually become transparent toward their foot.

On the Layer Properties - Transparency tab, in Custom Transparency Options, I found Transparency band and would like to use it.

enter image description here

Problem is, I do not know how to control the transparency according to the band I have just assigned (Band1 in the above image).

At default setting it gives me an uncomfortable image (right-hand-side; below).

enter image description here

I also tried simple color ramp such as Reds, but the output is still weird.

enter image description here

Question: How can I use this Transparency band function ?

Alternatively, giving a list of transparent pixel seems to work. But I have to give a color range in stepwise manner, and it is far from gradual change I hope to achieve.

enter image description here

Note: I borrowed the West Timor elevation data from SAGA GIS Tutorials - Downloads.

  • mh I don't think that's what you want; the band-wide transparency is meant for single pixel color transparency, specified by exact RGB values. I'd rather go for the Singleband pseudocolor rendering, create a color ramp with a few colors and assign opacity to each color individually? the opacity will be interpolated over the ramp. – ThingumaBob Dec 18 '18 at 13:06
  • Thanks so much @ThingumaBob ! I am still reluctant to give up on this Transparency band trick (if any), but your suggested color ramp technique definitely gave me what I wanted. – Kazuhito Dec 18 '18 at 13:31
  • @ThingumaBob please, will you post your comment as an answer so that I can accept as solution? – Kazuhito Dec 19 '18 at 9:18

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