Surface IGES import files

  • The following steps will allow you to import a surface IGS file, identify bad faces, replace or repair bad faces and stitch the surfaces into a useable body.
  1. Import surfaces
  2. Perform a 'Check Body Validity' which is found in the SOLIDS/TOOLS menu. This will identify any surfaces with errors and de-select them.
  3. Stitch the remaining selected surfaces using the stitch function on the surface modeling pallet. 
    note: Multiple passes with .001" tolerance is a good setting to start with.
  4. Identify problem areas in the part (holes, edges out of tolerance, etc.) by unchecking Show Internal Edges on the stitch pallet and turning on Edge Selection. This will allow you to view only the edges not stitched properly and will make it easier to see the areas you will need to work on. Be sure not to close the stitch dialog as this will make all edges visible.
  • See specific directions for correcting different problems below:
Identify and correct surfaces that do not stitch within the set tolerance

If you see gray edges with edge selection on and show internal edges unchecked then you have surfaces which were not able to be stitched together within the allowed tolerance. One method for correcting this is to unstitch one of the surfaces, un-trim and re-trim the surface with the geometry from the surrounding edges.

Start by identifying and selecting one of the surfaces adjacent to the bad edge. You will need to have face selection on in order to do this. Unstitch this surface from the main body and place it in the body bag for now. You should be able to see the gray edge around the hole created by the removal of this surface. Double-click on the gray edge (thus selecting all the edges around the hole) and extract the geometry with zero (0) tolerance. Next, bring the original surface back out of the body bag, be sure it is selected, and select the trim/un-trim function (on the surface modeling pallet). Now, select the body AND the extracted geometry and select the trim/un-trim button. You can delete the surface outside the trim area now and stitch the newly trimmed surface to the main body.

Building surfaces for holes left by bad surfaces

In order to fill a hole in the body you will almost certainly need the edge geometry. Extract the geometry by selecting all the edges around the hole and using geometry extraction (on the geometry pallet). Extract the geometry with zero (0) tolerance.

Next, determine how you can re-create the surface. If the bad surface was planar (flat) you can use the plane function (on the surface modeling pallet) to re-create the surface. You do this by selecting the geometry and clicking on the plane button. Please note that the surface will be created at the zero level of the plane you are in and not at the level of the geometry. You may need to create a coordinate system in order for this method to work properly.

The most common method for rebuilding the surface is to build a coons patch (on the surface modeling pallet). The coons patch function requires a three or four sided closed geometric shape. Each side of this shape can be made of curves (or splines) but the total number of sides must be three or four. If your extracted geometry has the correct number of sides but there is a yellow terminator at the intersections instead of a blue connector you will need to connect the shape into a closed blue shape. In many cases the extracted geometry will have more than four sides. You can still use coons patch if you can reduce the number of sides. A good method for doing this is to build a single spline from several. You can do this by selecting several curves and performing a 'Segment Spline' (in the modify menu). Then, select the resulting points in order and select the curve function (on the geometry pallet) and generate a spline.

After building a new surface be sure to check it for errors before stitching it to the original surfaces. Also, after stitching the surfaces make sure to check for any gray edges that may indicate an edge that was not able to stitch within the set tolerance.

There are literally hundreds of methods for creating, modifying and correcting surfaces, The methods listed above are a good starting point but be creative. If you find yourself stuck you can send your file to and we will do our best to help you through this.