Hi,

i am really desperate because i try to achieve a certain effect since hours and i basically just do not succeed

I need to colorize a random shape with a rainbow color gradient. The tricky thing here is, that the color gradient itself should have a "wave like" appearance. To clarify my problem i made some simple drawings:

A) shows the straight forward thing. Its easy to set up a color gradients, add steps, adjust offset etc. but the thing i need is B)! I need to individually change the course of each color. E.g. i want the turquoise gradient to form such a curve. Consequently i need all the other colours behind also to form that curve leading to an harmonic overall picture. I tried to cut my shape in smaller columns and colorize each one individually (like pictured in C) but i never get a harmonic alignment to the colours of the neighboring columns



The final result should look a bit like that (stolen from the internet) heatmap. Irregular colored like i draw the gradients with the cursor. Of course way to blurry but is shows what i need.



In reality its not a rectangle that i need to colorize but a random shape. I hope that does not play a role for helping me.

Thank you so much
Mike

Welcome aboard!

This calls for a gradient mesh, which is not part of the svg standard -so not an officially announced feature.
http://www.inkscapeforum.com/viewtopic.php?f=6&t=18467.

Though if that's for a raster image, you could also hack some other solution, like drawing a simple greyscale image with blur filters, exporting to png, then map another gradient to it, with gimp for example.

Apologies if I got you mixed up with someone else. One of the regular posters (and I can't remember who) frequently implies that filters are usually a bad idea because they result in raster images. When you wrote "Though if that's for a raster image..." before suggesting the use of filters, I jumped to the wrong conclusion. Sorry.

In this case, though, I don't see the need for a "map to gradient" function, and therefore no need to move to a raster format. The OP sounds like it's a manual process he's looking for to create a purely visual effect. It looks to me like some blurred coloured shapes will do the job well enough within Inkscape, without the need to move to a raster editor.

My thought was that for a heat map it would be nice to change the colours assigned to each isoline after easily.
(Maybe the swap colours extension can come handy this case.)

Hello,

I'm going to do some "self-marketing" here.

Perhaps in the links above there is a similar tutorial, or a link to This tutorial:


The general idea is, group several paths, blur that group, and then apply a clip-path.
I think that, at least in this case it's better than using the gradient mesh tool. Manipulate the handles of the gradient mesh may be tricky (the last time I tried).

I don't know if mike0815 wants to preserve its image as a vector, or just export it as raster. In the past, I've seen that some filter effects aren't good rendered in all the web-browsers. Just saying.

Greetings

Edit: I was sooo excited to show my tutorial that now I read my own description, I think It may not be the exact recipe the user is requiring. Bluring, grouping and cliping, I truly think needs to be used in the solution, but there is no need to make clones, or create a matrix of patches. The "interpolate attribute in a group" extension will be the key to solve the problem... and reading the Inkscape Guide

Just found this.
So svg filters are capable of gradient mapping, achieving it with inkscape is yet another thing.

Lazur URH wrote:Just found this.
So svg filters are capable of gradient mapping,

I don't see how gradient mapping will help here

achieving it with inkscape is yet another thing.

especially when inkscape has no UI for this (plus the feFunc are buggy in inkscape)

v1nce wrote:I don't see how gradient mapping will help here

You are right, I mixed it up with this similar topic probably.

achieving it with inkscape is yet another thing.
especially when inkscape has no UI for this (plus the feFunc are buggy in inkscape)

The reason of getting back to it is because I came across this clipart, and thought a turbulence filter would look the exact same, if a gradient could be mapped over it.