## A Feature Line Tool for Grading Transitions

A few weeks ago, I was asked about some of the LDT 3D polyline tools and their Civil 3D equivalents.Â

One question that I didn’t have a good answer for was the 3D polyline transition tool.Â  When you are actively drawing an LDTÂ 3D polyline, you are given the choice to pick a vertex location and either assign an elevation or transition to the next point.

LDT would figure out the grade between your two known spots and assign an elevation to the middle point based onÂ constant slope between them.Â  When you are actively drawing a feature line, you don’t get that choice, so for a little while we were stumped on the fastest way to accomplish this task with feature lines.

(Of course if I had my brain turned on I would have remembered a post I read a few months ago on Stephanie’s Civil 3D Investigation Blog.Â  Stephanie has more commentary and step by step than I do, so check her post out at http://wdc3d.blogspot.com/2007/01/transitioning-away-from-transitions.html)Â

One of the gentlemen I am working with right now was experimenting with some of the feature line tools and found the Set Grade/Slope Between Points button.Â  Now that we see it, it makes perfect sense.Â  But we were so hung up on looking for that word “transitions” that we didn’t see the forest for the trees.Â  This button does what we need.

So, perhaps I have some known building corner shots, and the building isn’t so critical that I need to send my crew out to get that last shot, but I really would like a decent breakline.

I make a feature line and just ignore any vertex elevations that I don’t know.

Then choose the Set Grade/Slope Between Points tool.

The tool will prompt me to choose my start point and my end point.Â  It will read their elevations and give me a chance to accept the grade it figured out, OR enter something different.

Now my intermediate point has been transitioned.

This isn’t just for one point.Â  If you have multiple vertices between known points, you can use this tool to apply a constant slope between them.

And remember- if you don’t use a feed reader, you can subscribe to www.civil4d.com in your email.Â  You’ll get an email every morning with yesterday’s posts.Â  To sign up, go hereÂ  http://www.civil4d.com/index.php/2006/11/get-civil-3dcom-in-your-email/

### One comment

1. Stephanie says:

Great post Dana. You reminded me that I still had info on using styles with feature lines that I wanted to post, so I finally got that up today. Check it out and let me know what you think. (http://wdc3d.blogspot.com/2007/03/we-now-return-to-our-feature.html) I don’t think it fixes your drainage path slope problem, but it could be a step in the right direction…