Feature line flow arrow direction expression

[troma]

Here is my flow arrow and the expression:

Now, in my understanding, the flow arrow should either be rotated 0, or 180  (pi radians).  But clearly, some of them like to have their own mind about things, and decide on some other rotation.  It seems that on the steep slopes, the arrows go a bit skew.

A little more investigation:  I think the skew is related to the actual elevation difference of the segment, rather than the steepness of the slope.  A long segment with 15% slope has a worse skew than a short segment at over 30%, presumably because the elevation difference from the start to the end of the segment is larger.

Obviously, I would like all my flow arrows to be parallel to the feature line in plan.  Any suggestions?

[Ed.McGriskin · Accepted solution]

Interesting. I have a similar label with the same expression and I wasn't able to recreate what you have occuring. My guess would be either something to do with the anchor point or anchor component. 

[troma]

Are you using a 'Direction Arrow' component or a block as your flow arrow?  It works fine for me if I use a Direction Arrow, but I need to use a block.

Thanks.

[Ed.McGriskin · Accepted solution]

I just use the flow direction arrow.

What is the block anchored to? I created a quick block and anchored it to the direction arrow and with the rotation specified by the expression. I set the direction arrow display to false after. It seems to be working. 

[troma]

Beautiful!  I just had it anchored to <Feature>.  Something about that large elevation difference in the featureline throws it off, but anchoring to a hidden direction arrow is perfect, thanks!

[Ed.McGriskin]

Anytime.

[dasindog]

I know you've already found your solution but I use your originial idea and it worked fine with the only difference being the expression was formatted as a double not direction. Maybe that was just an oversight?

[troma]

Didn't make any difference here.  Maybe it's one difference between 2011 & 2013?

[dasindog]

Quite possible. Anyway... at least you got what you wanted.

[kiss]

Hello Gentlemans!

I have only one question about this topic, which is not clear for me, how/where do you add this expression to the label style?

I would like to use this for profiles, to show the flow directions.

[1wildwes]

How do you add the Expression to the label?

[1wildwes]

Did you ever figure this out? I'm having the same problem.