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I am currently working on my thesis and I would like to ask you: does anybody know the mathematical formula that calculates the color gradient in Arcgis and Qgis? In other words, which mathematical equation is used to represent the color transition from one color to another in a buffer? And also: is there a different equation that calculates the color classification in other shapes, such as square, circle etc? A good example can be found in How to Calculate Color Gradient (, but this is rather general. I would prefer something that concerns Qgis and Arcgis.

EDIT: 20/01/2013 enter image description here

The arrow doesn't mean anything...

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Could you add an image of the gradients you are talking about? – underdark Jan 20 '13 at 11:02
As far as I know, there is no such gradient feature in QGIS. – underdark Jan 20 '13 at 20:24
What method did you use to produce the color gradient? – Aaron Jan 20 '13 at 21:41
This image is a buffer from Arcgis 10.1 – Vassilis Jan 21 '13 at 18:09
"underdark" If I am not mistaken Qgis I think has a plugin fro gradient. – Vassilis Jan 21 '13 at 18:11

Hopefully this might help I dont really know how its calculated but from your picture i think that you can calculate the green raster's slope using terrain analysis to try figure it out

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