Author Topic: Minimize Flat Areas  (Read 3331 times)

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reno

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Minimize Flat Areas
« on: March 27, 2010, 10:54:29 AM »
So, what do ya'll think?  I've heard conflicting information about the minimizing flat areas option when adding contour data to a surface.  Some things I have read say not to use swapping edge options yet others have said to use them all. Any suggestions?

mjfarrell

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Re: Minimize Flat Areas
« Reply #1 on: March 27, 2010, 11:10:44 AM »
I tend to not use any of the minimize options...in that I am relying on the Survey crew to collect the data with a density that is appropriate to the size/and scope of the site...

while this is an excellent question; I haven't performed a series of logical test wherein I used the SAME data and various combinations of the optional:

Filling Gaps In Contour Data
Specifies that small gaps in contours should be filled in.

Swapping Edges
Specifies that a encounter common edge shared between a flat triangle and a nonfat triangle should be swapped.

Adding Points To Flat Triangle Edges
Specifies that a new point should be added at the midpoint of an edge shared between a flat triangle and a nonfat triangle.

Adding Points To Flat Edges
Specifies that a new point should be added to edges that bridge two salvation data contours and are not in flat triangles.

To answer the question definitively one would want to start with the same contour information...
and then build one surface each using NO minimize options, One option, Two options, etc until ALL possible combinations were used.  Then compare the resultant surface objectively to each other; and the ACTUAL site conditions. 

I do not have time to perform those iterations today.  Further I have also had negative experiences when employing all, or some of those options with different data sets. (C3D terminates abnormally)

I guess that places me in the NO minimize option camp, in that I use weeding factors on the contour data intended to maintain fidelity with the original information as much as possible.
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Michael Farrell
http://primeservicesglobal.com/

mjfarrell

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Re: Minimize Flat Areas
« Reply #2 on: March 27, 2010, 12:39:59 PM »
As a follow up question to the above; how or why is it that you find yourself with ONLY contour data to work from?

There might be other methods to consider.

Or are they being used as supplemental data?
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Michael Farrell
http://primeservicesglobal.com/

reno

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Re: Minimize Flat Areas
« Reply #3 on: March 27, 2010, 02:26:44 PM »
Hmmm, you're the first I've heard of that says not to use any of the minimizing options.

As far as where I got the contours, it was some legacy data from an old project adjacent to the one I'm working on and I wanted to use it to help me delineate the drainage boundaries.

mjfarrell

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Re: Minimize Flat Areas
« Reply #4 on: March 27, 2010, 04:56:45 PM »
Hmmm, you're the first I've heard of that says not to use any of the minimizing options.

As far as where I got the contours, it was some legacy data from an old project adjacent to the one I'm working on and I wanted to use it to help me delineate the drainage boundaries.
Again, the reasoning behind doing 'nothing' to the data from contours, I want to keep fidelity to whatever the original information given was.  As one can imagine I use small weeding values.  I'm working from the position that all due care was taken in collecting and processing the original survey data to create the TIN from which those contours were derived.
If it is legacy data, why not import that surface from the LDD project directly, instead on working with the contours?(given that it was a land desktop project)
Otherwise I would suggest importing the break line information (layers or objects) using Map, and importing the point data and recreate the surface in that manner within C3D.
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Michael Farrell
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sinc

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Re: Minimize Flat Areas
« Reply #5 on: March 27, 2010, 07:33:08 PM »
If you are creating a surface from triangles, you will in most cases get better results if you DO use the "Minimize Flat Surfaces" options.

I usually just leave the options set to the default, with everything on except "Swapping edges".  Based on what they do, it might be good to turn off the options for adding points, if you turn on the option for swapping edges, since both of those target the same basic problem.

You can always just try it a variety of ways, and use whichever one seems to work the best on your data.  It's so easy to do, that's an option.

mjfarrell

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Re: Minimize Flat Areas
« Reply #6 on: March 27, 2010, 10:28:54 PM »
Yet another way to test the effects of this would be to go to the Toolspace>>Surface Properties>>Surface Definition Page>>Edit Operations and toggle Use Minimize Flat Faces from YEST>>>to NO
If you liked the surface better before...reset to YES
If you liked it better set to NO no need to do anything
Be your Best


Michael Farrell
http://primeservicesglobal.com/