Trim an existing surface?

[deltacoolguy]

Trim an existing surface?

I have a large surface that already exists.  I want to trim it and make it smaller, like trimming a line.  I do not want to just hide it with an outer boundary.  I tried Data Clip, and referenced this resource ( http://beingcivil.typepad.com/my_weblog/2014/03/trimming-tin-surfaces-with-data-clip.html ).

These instructions say you have to apply the data clip prior to creating the surface.  My surface already exists.  I tried creating a new surface, apply the data clip, then past in the old surface.  No go.  I tried creating a new drawing, create a new surface, import an XML of the surface.  No go, as well.

Is there a way to get what I want?

[mikeevans6697]

I think you misread the instructions. You need to apply the data clip, then in the surface properties, move the data clip to the top of the edit list: " Go to Surface Properties, and in Definition tab you will see that Add boundary is there. Change the order by moving Add boundary to the top and Rebuild your surface."

[BrianHailey]

An outer boundary doesn't simpley hide the display of the surface, it hides the surface. In essence, there is no surface there. Why doesn't this work for you?

[neilyj666]

Never had much success with a data clip boundary so typically use Outer instead

[jmayo-EE]

I gave up on these a while ago. I'm pretty sure the data clip only works in the source file and when the source surface is defined only by points, breaks or drawing objects. It does not work on a data referenced surface, an xml srf or if you have pasted any other surfaces into the surface to be clipped.

[Neilw_05]

If you are wanting to keep the original surface intact and maintain a dynamic link to it, consider the crop surface tool (not clip).. It works with shortcuts and pasted surfaces. There are several forum posts that migyt 'be helpful.

[BrianHailey]

Good call! I had forgoten about the cropped surface. I still think applying an outer boundary would be the best option in most cases though.

[Neilw_05]

I agree.

[Civil3DReminders_com]

While it doesn't trim the surface, you can apply a mask via a polyline that will hide everything outside of the mask, but still show the surface inside of it and you can still get information from from surface outside of the mask. I'm only mentioning it because it wasn't mentioned in any of the other answers and there is a small chance that is what you are looking for. I usually use this method when data shortcutting large surfaces into the drawings to reduce the amount of contours that need to be shown.

[sboon]

A data clip boundary is a filter applied to the data before it is used to construct the surface TIN.  Data outside of the boundary is not imported at all, so it's not used for TIN construction.  When you paste a surface or use a data reference to import from another drawing what you're getting is an already constructed TIN, which is why the data clip boundary is not applicable.

An outer boundary is applied after the TIN is already built or imported.  TIN lines and points outside of the boundary are deleted and, depending on settings the lines crossing the boundary are either trimmed or deleted.  The important thing to remember here is that all of the data is used for TIN construction, then the extraneous data is removed.  This happens every time the surface is rebuilt.  For a large data set this can be very inefficient.

A mask hides some of the data for an existing TIN, but it's still part of the drawing.  This can mean that your files are bloated with un-needed data.  Also, you can only have one mask for each surface.

The choice of which type of boundary you use is dependent on what your source data looks like, and how you plan to use it in the current drawing.  Good luck.

Steve
Please use the Accept as Solution or Kudo buttons when appropriate

[deltacoolguy · Accepted solution]

I ended up going with the outer boundary and hiding.  It's fine, and works, but is not what I ideally wanted.

Anyway, than you to all who chimed in.  It is appreciated.

For what it's worth, I have since used data clip on a completely new surface (in another project) and it worked great.

[Neilw_05]

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@deltacoolguy wrote:

I ended up going with the outer boundary and hiding.  It's fine, and works, but is not what I ideally wanted.

I presume from your original post that you want to actually clip the surface rather than just hide the outer portions with a boundary. Clipping it actually reduces the amount of data that is processed to create the surface which is preferable when the surface is large.

As you have learned, you cannot clip a DREF surface. However it is my understanding the Crop tool does essentially the same thing (clips the unwanted data). The main difference is the Crop tool creates and stores reduced pieces of the surface in separate drawings which you then use in your project as needed. Those pieces can be synchronized to changes in the master surface so it is a dynamic solution. 

[deltacoolguy]

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@Anonymous wrote:

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@deltacoolguy wrote:

I ended up going with the outer boundary and hiding.  It's fine, and works, but is not what I ideally wanted.

I presume from your original post that you want to actually clip the surface rather than just hide the outer portions with a boundary. Clipping it actually reduces the amount of data that is processed to create the surface which is preferable when the surface is large.

As you have learned, you cannot clip a DREF surface. However it is my understanding the Crop tool does essentially the same thing (clips the unwanted data). The main difference is the Crop tool creates and stores reduced pieces of the surface in separate drawings which you then use in your project as needed. Those pieces can be synchronized to changes in the master surface so it is a dynamic solution. 

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You are absolutely correct on my original intent.  I was using an existing surface that had been cobbled together in previous adjoining projects over a period of several years, and I wanted to clean it up and bring down the size by having only the small area I needed.

I will try the crop option next time.