Gradient color line symbology

[ChristopherBlinn1]

Hello,

Not sure if this is possible but I would like to create a gradient line symbology.

I have a line feature class that has a field populated with 4 values, "1_1", "1_2", "2_1", and "2_2".  I want to create a gradient line for two of the values, "1_2", and "2_1".  For lines with "1_1" values, they are colored Blue; for lines with "2_2" values, they are colored dark Yellow.  I want the "1_2" line to be a gradient from Blue to dark Yellow, respectfully, and vice versa for the "2_1" lines.

Can this be done? Any help would be appreciated!

-Chris

[MarkEllis]

You might try buffering the line to an polygon of apt width.  Different values can be different polygons with their own symbols.

[JimW1]

I've done this with line buffering (sorry no examples on this computer) but basically you can buffer each type 1_1, 1_2, 2_2, etc. as single features and then buffer them. Then put a gradient fill on each polygon value as you've described.

It isn't perfect.

Actually re-reading your question I'd say the answer is yes it can be done (through buffers) but it is going to take a long time to make it look good.

Good luck. Please post if you get it to work b/c it's a great visual idea.

[ChristopherBlinn1]

Awesome, making buffers (very small ones, with flat edges) worked like a charm.  I did this to make the QA/QC of our road network a lot easier.  We added to and from elevations to make our network connectivity more accurate and we need to triple-check the data before using it for route analysis and service area projects.  Attached is an image of how we will use it.  The yellow streets are 1_1, meaning the to and from elevations do not change.  The 1_2 and 2_1 streets are for changing elevations, and use a yellow to red or vice versa color ramp, and 2_2 roads are all red.  It makes it easy to find errors, which you will see in the image.  Thanks for all your help!

[ChristopherBlinn1]

Well, I have discovered that this is not the best approach.  The polygon buffers draw the gradients at a specified angle, rather than drawing the gradients in respect to the to and from's (duh).  There probably is no practical approach.  However, this will help highlight any areas that could be wrong, which helps a little bit.  Oh well.

[MarkEllis]

Have you tinkered with gradient fill for your narrow polygons?  Not sure if it will work consistently with a data defined 'from' and 'to', but it might be worth a look.

[ChristopherBlinn1]

Hey Mark,

Yeah, the above post with the attachment was just that; a very thin polygon with gradients, but the approach does not work entirely, because of the to and from.

[JimW1]

Well, I have discovered that this is not the best approach.  The polygon buffers draw the gradients at a specified angle, rather than drawing the gradients in respect to the to and from's (duh).  There probably is no practical approach.  However, this will help highlight any areas that could be wrong, which helps a little bit.  Oh well.

I was going to ask how you dealt with the angle issue for the gradients...

Just brainstorming - I am a big fan of using colour to QA/QC data:

If your 1_2 lines a digitized/stored directionly (to-from) then you could repurpose a script to divide the lines into equal sections
You could then generate sections at say 1, 1.25, 1.5, 1.75, 2.0.
You could then assign colour gradients to the sections
1_1 1.0 is Red
2_2 2.0 is Orange

Then :
1_2 1.25 is Slightly less Red
1_2 1.5 is half way between red and orange
1_2 1.75 is almost orange

2_2 is Orange

2_1 1.75 is almost orange
2_1 1.5 is half way between red and orange
2_1 1.25 is Slightly less Red

If I had some free time I'd do a mock-up but in my mind this could work.

[ChristopherBlinn1]

I was going to ask how you dealt with the angle issue for the gradients...

Just brainstorming - I am a big fan of using colour to QA/QC data:

If your 1_2 lines a digitized/stored directionly (to-from) then you could repurpose a script to divide the lines into equal sections
You could then generate sections at say 1, 1.25, 1.5, 1.75, 2.0.
You could then assign colour gradients to the sections
1_1 1.0 is Red
2_2 2.0 is Orange

Then :
1_2 1.25 is Slightly less Red
1_2 1.5 is half way between red and orange
1_2 1.75 is almost orange

2_2 is Orange

2_1 1.75 is almost orange
2_1 1.5 is half way between red and orange
2_1 1.25 is Slightly less Red

If I had some free time I'd do a mock-up but in my mind this could work.

Yeah, that is a good idea and I think it would work too.  I am not the best scriptor, really just started doing it a few months ago, but maybe I'll get brave and try it out.  Right now I have bigger fish to fry, but thanks for the idea.  If I move forward and do this I will post back in this forum the results.

[FrancescaR_]

Has anybody found a way to achieve this without the need of splitting the lines? It is weird ArcGIS doesn't provide gradient symbology for lines considering other non GIS specialized software do (e.g. R).

I need the From-To direction to be maintained.

Thank you!