Autodesk Civil 3D 2011 Do you have a huge cumbersome surface that you need to cut down to a manageable size in Autodesk Civil 3D? There are a few ways to help make that happen.

  • One is the Cropped Surface tool from the Civil 3D 2010 Subscription Advantage Pack
  • Next is to delete data directly from the surface until it is sized according to your needs.
  • Lastly Civil 3D 2011 already has the SAP features adopted, and Create a Cropped Surface is one of them

Autodesk Civil 3D 2010 Subscription Advantage Pack

This add on is available available in the Autodesk Subscription Center for subscription members only.

Autodesk Civil 3D Subscription Advantage Pack Digital PrototypingThis awesome tool provides numerous enhancements for Civil 3D 2010, one of which is Cropped Surfaces Export. The predecessor to the Create Cropped Surface tool in Civil 3D 2011, it does just what it’s name implies – Create a new cropped surface from the one you already have. See below for more details.

Direct Editing

This tip is for anyone trying to cut down a huge surface by directly editing the points or triangles. Maybe you don’t have 2011, or are not on subscription (and really wish you did right now). Deleting points or lines is the standard way to take the surface down a notch without losing any precision. However, if you are trying to edit a very large surface, you may find problems and lockups trying to delete thousands of lines or points during the edit procedure.

Typically we would display Points and Triangles in the Surface style during the editing process, as each has to be displayed in order to delete both types.

If you are only hacking off huge chunks, BOTH don’t have to be displayed.

This example surface is derived from a 30 meg XML file, and it is horrible. It takes 10 minutes to refresh from just selecting 10% of the points with Points and Triangles shown.

Autodesk Civil 3D Edit Surface

Here is what got me past that: Turn Off The Triangles !!!!

Points take up substantially less space than triangles. I suspect the bog down is a result of Civil 3d filtering off all the lines. When the lines are turned off, the response is remarkably better, almost comfortable.

Autodesk Civil 3D Surface Style

If you do this type of procedure a lot, then make a new display style for cropping with only the Border and Points shown.

Civil 3D 2011 Create Cropped Surface Tool

This tool is awesome, and not just because it can crop a surface. No, it can send that surface to existing drawings and create new ones as well.


First, position the drawing so that you can see the area to crop, and then save. The tool won’t initialize unless the drawing has been saved immediately prior to use. The tool is then accessed through the Home tab of the Ribbon. Pull Surfaces down from the Create Ground Data Panel, and at the bottom you will find the Create Cropped Surface Tool.

Autodesk Civil 3D Surface Style

The Create Cropped Surface Dialog will appear. Most of the options are self explanatory, so I will just hit the high points, moving from top to bottom.

Autodesk Civil 3D Create Cropped Surface

Select Surface to Crop

Select the desired surface from the pull down. This contains a list of existing surface objects in the current drawing to choose from.

Select Crop Area

This button will minimize the dialog, and allow you to pick a window in the graphics view area, or alternately you may enter command line options for Object or Polygon selection. I opted for Polygon in the image below.

Autodesk Civil 3D Command Line

Once selected you may pick an object, or point to point a polygon area. The command will leave the polygon outlined in Yellow.

Drawing for New Surface

Pull this down and select where you want the new surface to be stored: A New Drawing, an Open Drawing, or an Existing Drawing.

Autodesk Civil 3D New Drawing Option

New Surface Name and Description

Don’t forget the Name. For whatever reason I kept missing this field, and the command would not complete. Just type in what you want the new surface to be called in the target drawing.

New, Existing, or Open Drawing Selection Fields

These are subdued except the option corresponding to the selection made just above. When picking new drawing, you will be asked to select the new template first, and then the path to store it at. In all cases, the target drawing is opened and brought into focus. One thing that I liked is that if only two drawings are opened, the target drawing is automatically set.

Surface Style and Layer

Identifying which style and layer will be taken care of by the new drawing’s Command Settings if nothing is specified.  You will want to make sure that any templates used for new drawings have the desired Surface Style and command settings in place before this process.

Once the required fields are filled, the application will activate the OK button. Hit this and the surface creation is completed.

Reference Warnings

This process is fouled by surfaces that are referenced. Everything will seem to go ok, but you will receive a warning if you try to crop an XML or Data Referenced surface. This is easy to fix, simply select the surface and pick ‘Promote’ from the right click context menu. Now when you try it, everything works smoothly.

I read somewhere that in some cases the new surface will not appear until the Snapshot is rebuilt. I have not witnessed this, but if you have trouble with this, just right click the new surface, and pick Rebuild Snapshot from the context menu.

Autodesk Civil 3D Cropped Surface Result   Autodesk Civil 3D

The Cropped Surface tool is but one more reason to consider jumping on subscription and getting the SAP for 2010, or just moving ahead to 2011.