Monday, July 26, 2010

Stop!! Exploding Grading Objects, Really Stop

I’m quickly approaching 500 posts. Instead of creating new and different posts I’d thought I’d recycle some posts leading up to the 500th post. (Hey! TV shows do it all the time.) This post I think needs repeating. If your exploding grading objects, cut it out and do it a better way.

Well not all the time. If you are exploding grading objects to get the daylight line and then adding the daylight line back to the surface along with the feature you should stop. What should you do instead and why? Well this post will answer those pressing questions.

First the How? You should detach the surface from the grading and then add then paste the surface to the design surface. Here’s the steps on how to do this. First go into the Grading Properties and deselect the Automatic Surface Creation checkmark. Detaching a surface is also available from the Grading Creation Tools.


A warning message will pop up, when it does press the No button.


Then press OK to get out of the Grading Group Properties window. You will get another warning message and press OK.


So now you have two separate non dynamically linked objects in the drawing. Go ahead and delete the Grading Objects in the grading group and paste the surface into your design surface for the daylight.

So that was the how, now the why. A daylight line is created with lots of vertices, probably more than the feature you graded from has. So when you add the daylight line to the surface you don’t always get the result you are after. The picture below shows what can be missing and how the triangulation may be wrong.


The detached grading surface uses all of the data that created the daylight line. If we take a look at what makes up the detached grading surface we can see all of the stuff we’re missing.


So as you can see there is much more to grading object then a daylight line and a feature line. There are boundaries, projection lines and legs which help make sure the daylight grading is accurate.

As a bonus tip, to when your ready to create an overall surface boundary, extract the individual surfaces’ boundaries, flatten if necessary, and use the AECLINEWORKSHRINKWRAP command to combine them into one large boundary.


Anonymous said...

I've used this method before. It often results in a file that likes to crash and/or become corrupted.
That's why I started exploding them.
There are also times when you need the original grading object out of your way. C3D used to give me an error message about overlapping grading objects within the same group, or within the same site (sorry it's been a while since I've done it this way, so I can't remember exactly what the problem was).
Anyway, exploding the grading object cut my grading time significantly.
Now, that was with 2008 I suppose 2010 and beyond may be better.
Thanks for the tip anyway. Maybe I'll try this method again sometime.

Christopher Fugitt said...

With this method you delete the grading object once you extract the surface, I haven't come across any crashing issues as long as I delete the gradings.

Anonymous said...

I know this is an old post, but I am having an issue with grading objects in C3D 2012. What if you want to keep the grading objects because you are using the slope patterns that are apart of the grading object style for your construction drawing?

Christopher Fugitt said...

I'd use the SAVE command to create a copy of the drawing, explode the gradings, and then paste the resulting slope patterns into the original drawing. This way you get a good surface and are able to get rid of the crappy grading objects.


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