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Arrowhead the same color as the line...

August 31 2010 | 5 comments
Categories: Symbology


I've created a couple thousands of water velocity vectors and want to represent them as arrow. The problem is that when I create my line and add the arrowhead (which is black as the default) the color stays the same when I choose my symbology for the line (I have 18 classes). So I have blue-green-yellow-orange-red lines all with black arrowhead. Is there a way to make the arrowheads to change color when I chose the color ramp for my classes? Or do I have to change 18 lines styles separately. I could create points at the end of each line, give it the attribute and angle of the line, use that to change the rotation of a symbol to which I'd give the same symbology as the line, but it seems quite a job for something that should be simple (I mean, I change the color of my line, the arrowhead should logically change as well - otherwise, there's something on which the development team should work... ;)


Mapping Center Answer:

It sounds like you have a "lock" on the arrowhead part of your symbol which is not allowing the color to change when you apply the color ramp.  If you edit the symbol using the Symbol Editor, you'll see a lock/unlock symbol to the right of each symbol layer.  From the online documentation, "About creating new symbols":

"Symbols can be made up of more than one layer. By default, the first layer is unlocked and each subsequent layer is locked.

If you change the arrowhead layer of each symbol from from locked to unlocked, applying the color ramp should change the whole symbol and not just the line portion.


Thanks, but... posted by Francois Turcotte-Goulet on Sep 1 2010 9:30AM

I double checked and there's no lock on that part of the symbol.
I have a screenshot of the Symbol Property Editor:

Still investigating... Thanks!!
Another idea - marker line symbol posted by Aileen Buckley on Sep 1 2010 2:09PM
We originally missed the fact that your data are lines, not points. If they had been points, the solution above would have worked.

Unfortunately, it is not possible to have the arrowhead color update automatically to be the same color as the line. As you surmised, you would have to create 18 different symbols with the colors you want for both the lines and the arrowheads and then apply those to your classes.

However, it appears that most or all of your vector lines are about the same length (that is why we originally confused them for points). If that is the case, there is another solution you can use. Essentially, what you would do is instead use a marker line symbol and set the position of the marker along the line to correspond to the end of the lines. Using this method, the line and arrowhead of your symbol will be recognized as one so that any color change you apply to the line will also apply to the arrowhead. Here is how you would do that:

1. In the Layer Properties for the vectors, on the Symbology tab, choose Quantities -> Graduated colors.
2. Click on any symbol and select Properties for all symbols and choose to edit the symbol so that you are in the Symbol Property Editor dialog.
3. Change the line Type to Marker Line Symbol.
4. On the Marker Line tab, click the Symbol button and again edit the symbol.
5. Change the Type of marker that will draw along the line to an Arrow Marker and set the properties as you had them before (select
the default symbol which is a triangle pointing right and click properties once again to set the length and width of the Arrow Marker Symbol to have a length of 4 and a width of 2.) As you did before, make sure that the arrow marker symbol is unlocked.
6. Click OK a couple of time to go back to the Symbol Property Editor for the Marker Line Symbol.
7. Click the Template tab. This is where you will set how far along the line the arrow marker symbols will draw. Click and drag the gray box over to the right as far as the line end will be (note that the interval and line pattern are in points so you may have to experiment a little.)
8. To add the line part of the symbol, add another layer to the symbol, set it to be a Simple Line Symbol and set the width to whatever you want to use. Again, make sure that this layer in the symbol is unlocked.
9. Click OK a couple of times to get back to the Layer Properties – Symbology tab. Here you can now select a classification and a color ramp. The colored lines and the arrowheads will now change color together.

If you have too many problems getting the markers to fall along the lines where you want them to, especially if your vector lines are of vastly varying lengths, then you might do better to go ahead and create those 18 symbols using the method you started out with and modifying the arrow marker that is the line decoration to be the same color as the line.

Hope this helps!
Oh well... posted by Francois Turcotte-Goulet on Sep 2 2010 7:55AM
Thanks Aileen!

My line aren't all the same size. They're proportional to the water velocity and in map units, they are from 10 to 30 meters long. I have about 15 classes, but the length are all different.

Thanks a lot for having take some time helping me! :)
Back to the 18 symbols posted by Aileen Buckley on Sep 2 2010 8:16AM
Sounds like it is time to go back to your original -- and as it turns out, very good -- idea to create 18 different symbols that you can apply to each class. But look at it this way -- you can use those symbols again on other maps! In fact, if you want to send the style to me once you have created all the sybmols, I will post it here on Mapping Center for others to use as well!
Any Progress in 4 years? posted by Tristan Graham on Apr 3 2014 9:28PM
Has there been any progress on this matter?
I am searching the net for solutions to the same problem in 2014 and can't find any reasonable solutions!!
I have velocity vectors with lengths related to velocity. I want to scale the colours but at the moment it appears I have to go in and manually change each arrowhead (thousands of them).
If anyone knows a way to fix arrow head colour to the line colour please post.

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