Esri Mapping Center - Ask a Cartographer

Color Ramp

November 06 2009 | 2 comments
Categories: Symbology

Why does the Color Ramp "No Color" option create grey polygons? I have tried a few different ways to create a ramp that goes from a dark color through its lighter hues and then to nothing (not white). For some reason, even an algorithm or preset color ramp with all colors set to "No Color" shows up grey which means you cannot add that to a multi-part ramp to cheat the effect in either. This is important when you cannot use transparencies or graphic buffers because it is going to be used in a web-based map service. Does anyone have a solution for this?

Mapping Center Answer:

This is pretty much the same quesditon we recieved JUST the other day! Weird! Take a look at the answer to this question: http://mappingcenter.esri.com/index.cfm?fa=ask.answers&q=1005. You will see that it is not possible for a color ramp to range from a selected color to No Color.

Have you checked out the Transparency option that is descibed in the "Fade to White" effect? We wrote it up in a Mapping Center blog a while ago: http://blogs.esri.com/Support/blogs/mappingcenter/archive/2008/10/14/fade-to-white-background-effect.aspx.

ESRI Software Solutions? posted by Jason Balmut on Nov 9 2009 10:06AM

As I mentioned in my original question, transparencies and buffers are not an option in the environment I am working in. Will this color ramp issue be updated in 9.4? If not the color ramp, will the web-based transparencies be allowed?

Not in 9.4 either! posted by Aileen Buckley on Nov 9 2009 2:40PM

You will not be able to use No Color as one of the colors in a color ramp in 9.4 either. The bottom line is that you cannot change the level of transparency in one section of a color ramp -- either now or in 9.4.

I am not really sure what you mean about "web-based transparency" so maybe you could let me knoe what you mean and I could try to help you a little more. It seems that you are working with polygon data so the Tranapraency option should be helpful IF you will be using a white background.

If you are not, or if for some reason you cannot use the Transparency option for symbology, then I think the next best thing is to set up a layer for each set of polygons that needs a different level of transparency. But again, I am not completely sure exactly what you need so maybe I am wrong about this.

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