Import DXF

Boundaries, support and other modelling entities (e.g. slip surfaces and search objects) can be imported into Slide2 from a DXF file (AutoCAD Drawing Exchange File), using the Import DXF option in the Import sub-menu of the File menu. This allows users to digitize drawings in AutoCAD, for example, and import them into Slide2.

Importing entities in DXF format is equivalent to adding them using the options within Slide2 (e.g. Add External Boundary, Add Material Boundary, Add Water Table, Add Support etc). That is, all the same rules apply, and entities will be automatically checked for validity, intersected if necessary, etc.

To import modelling entities from a DXF file:

1. Select Import DXF from the Import sub-menu of the File menu.
2. In the DXF Options dialog, select the entities you would like to import, using the checkboxes provided.
3. Select the Import button, and you will see an Open File dialog. Select the required DXF file and select Open, and all entities you selected in the DXF Options dialog will be imported into the current Slide2 document.

If boundaries already exist in your current Slide2 document when you use Import DXF, you may see a warning message if the imported boundaries are not compatible with the existing boundaries. For example, if you try to import a Material Boundary which is outside of the existing External Boundary. So always be aware of what is in your DXF file when you try to import entities.

Layer and Entity conventions

If you are using AutoCAD to create DXF files for import into Slide2, use the following conventions for layering and entity type:

Troubleshooting Problems with DXF Import

If you are having problems trying to import a DXF file into Slide2, this may be due to one or more of the following issues:

Layer Names

Check that you are using the correct layer name for each entity. A summary of layer names for the various Slide2 entities is given in the table above.

Layer Assignment

Check that the entities in the DXF file are assigned to the correct layer.

External polyline not closed

In Slide2, the External boundary must be CLOSED (i.e. must form a closed polygon with the first vertex equal to the last vertex).

Carefully examine your coordinate values to determine if this is the problem. Sometimes the coordinates of two vertices are very nearly equal but are slightly different in the last decimal places. Check all vertex coordinates and make appropriate modifications to ensure that the External boundary is continuous and closed.

Coordinates must be 2-dimensional and in the XY plane

Slide2 does NOT support the import of 3-dimensional geometry. All lines/polylines must be 2-dimensional and in the XY plane (Z = 0). If you have 3-dimensional (x,y,z) coordinates or if you have 2D coordinates which are not in the XY plane (e.g. XZ or YZ), then you will have to apply appropriate conversions and/or rotations to obtain the desired 2D geometry.

User Coordinates

Slide2 does NOT support the import of entities defined by User Coordinate Systems (UCS). The DXF file reader will only read coordinates in the World Coordinate System (WCS) with the 2D geometry (polylines, lines) on the XY plane (Z = 0).

Very large coordinates

If the absolute value of X and/or Y coordinates are very large, relative to the extents of the model, this may cause problems with DXF import due to numerical precision issues. Furthermore, even if the DXF import is successful, very large coordinates can lead to modelling difficulties and/or incorrect analysis results. If the X and/or Y coordinates in your DXF file are extremely large, then you should translate the entire model to the origin (0,0), to avoid potential problems. For example, if the Y coordinates of your model are around 100,000, then apply a translation which shifts the entire model by -100,000 on the Y-axis.

Measurement Units

Make sure that your measurement units are either meters or feet, according to whether you are using metric or imperial units in Slide2.

Too many closely spaced vertices

It often occurs that DXF polylines have a large number of unnecessary vertices (i.e. the geometry could be accurately defined with a smaller number of vertices). Also, vertices are often located very close to each other, due to the automatic creation of 2D sections from 3D geometry, or due to manual digitizing procedures.

Although there is no limit to the number of vertices which can be imported from a DXF file, it is a good idea to simplify the geometry as much as possible, by deleting unnecessary vertices, so that the geometry is accurately defined by a smaller number of vertices, and vertices are not extremely close to each other.

Recommended DXF Import Procedure

If you have gone through the troubleshooting tips (above) and you are still having problems with trying to import DXF geometry into Slide2, the following procedure is recommended.

1. In AutoCAD, save each entity from the main DXF file, into its own separate DXF file, by using the *.dxf export option in AutoCAD to pick each entity you want to export.
   
2. Import the DXF files into Slide2 one at a time, starting with the External boundary.
3. If you follow this simple procedure, this will often allow you to successfully import the DXF geometry into Slide2, and identify the source of any problems.
4. You might want to practice this procedure, by starting simple just to get the process down. For example: draw a simple external boundary in AutoCAD, and export it. Draw a couple of material boundaries, and export them. Now bring them into Slide2 in the same order, one at a time.

Save as DXF version 12

In some cases, it may help if you save the DXF file as (AutoCAD) version 12 or 13. However, this is not recommended unless you have tried all of the above options first.