Best Practice Building Surfaces

[DaveM]

All,

When building surfaces I typically attach survey figures first, then add a point group second. The point group i use excludes the point descriptions that create the breaklines. I recently had a disscussion with a coworker that thinks this is not the way to go. I am curious how others do this.

[ericcollins6932]

Yep, it does. That's why I like to bring in the points - gives me something to sort into groupsand then snap my breaklines to. Especially when there are lots of points.

[sboon]

If a breakline is added after the fact then there are three steps in the process:

- Any existing TIN lines which cross the new breakline have to be deleted.

- TIN lines are added along the breakline.

- TIN lines are added, connecting the breakline to adjacent points and closing any other triangles that were affected.

If breaklines are added to a surface first:

- TIN lines will connect the breakline points. 

- When random points are added then some TIN lines must be deleted if they don't actually run along a breakline.  Typically however the number of lines involved is much less than the previous scenario.

- New TIN lines are added, connecting the breaklines to adjacent points and the points to each other.

Every time you rebuild the surface it has to go through one of these sequences.  If you go into the Definition tab of the surface properties dialog and reorder things to add the breaklines first then you're making the process slightly faster.  Realistically however you would need a huge surface with lots of breaklines to be able to notice the difference in build time.

Steve
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[BrianHailey]

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@Anonymous wrote:

Let me try to subtract that con. 🙂

If this is field data the breakline points should not have to be removed. This should be done automaitcally via desc keys and point group  and surface data management.

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I didn't say it was a BIG con... 🙂