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Learn how to import 3D geometry into BUILD3D from third-party CAD software to simplify geometry creation.

This tutorial uses GeoStudio 2021.3 and will show you how to import 3D CAD files in the *.step, *.iges, *.dxf, *.dwg, and *.stl file formats.

What’s in this video?

0:00 Introduction
0:30 Three methods for importing CAD files
1:54 CAD File Types – Best Practices
3:26 Import Body in BUILD3D
5:00 Import Background Mesh in BUILD3D
6:47 Import Profiles in BUILD3D


9 min

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Video Transcript

<v Instructor>Welcome to the Build3D importing series.</v>

In this session, I will show you how

to import files from third party CAD sources

into Build3D to simplify your geometry creation.

This workflow is useful

for creating 3D analysis-ready geometry based on files

that have been created in CAD software,

removing the need to recreate the geometry in Build3D.

There are three methods

for importing CAD generated geometry into Build3D.

The first method is importing as 3D solids.

Three dimensional bodies can be imported directly

into Build3D if they are in the STP or IGES file format.

The second method is it importing as background mesh.

Surface meshes that have been created

in CAD software can be imported

as a background mesh in Build3D.

A background mesh can then be used for 3D sketching

or for the creation of a nerve surface, such as topography.

File format supported in this import type

include DWG, DXF or STL format.

The last option that I will cover today is importing

as a 2D or 3D sketch profile.

This third option for CAD importing is

through 2D or 3D sketch profiles,

which are useful or for importing design structures,

such as embankment cross-sections or tailings dam designs

into the three dimensional geometry.

File format supported in this import type

include STP and IGES format.

First, let’s talk about the different format types

that can be exported from CAD software.

When importing in the STP or IGES format as a solid,

it is best to ensure

that the body is a parametric representation.

For example, consider these three cylinders.

All three cylinders can be saved to the STP file format.

However, each have been created in a different way

and will behave differently when imported into Build3D.

The red cylinder is a parametric representation.

It is an extrusion surface consisting

of three parametric surfaces,

the bottom, the top and the curve side.

This is the prefer representation

of geometry in Build3D.

The green cylinder is a mesh representation of the surface,

it contains 50 vertices and 32 faces.

Build3D cannot import the cylinder as a solid,

but we will review it during the background mesh portion

of this video.

The blue cylinder is a polysurface.

A polysurface is a faceted nerves structure.

Build3D will read this representation

with each mesh face bred as a separate surface.

With this format,

you are able to use the geometric operations,

but it is not a preferred representation.

Let’s switch to Build3D so that we can import this file

with three cylinders to further illustrate

how these different representations are imported.

In Build3D, we will go to Import Body

and choose the cylinders.stp file.

This geometry was created in a third party CAD software

where the Z coordinate is the elevation parameter.

Build3D requires as Y coordinate as the elevation,

so we will first remap the axes using the dropdowns

before clicking on okay to finish importing the file.

Here, you can see

that the parametric representation imported the best

as it was imported as a single solid

with three simple faces.

The mesh representation could not be imported as a body,

so it doesn’t not show up in the geometry tree.


although the polysurface cylinder imported as a body,

there are now multiple faces for the same solid

in the geometry tree.

This leads to difficulty

with defining boundary condition assignments

and generating a clean mesh without first spending time

to clean up the solid.

Now, let’s look at a file

that was created using the parametric representation.

We will delete this import step in the design history tree

and go back to Import Body.

This time, I will choose the subway.stp file.

Once the file is remapped to the Y coordinate as elevation,

you can see that three solids have been imported

in the tunnel design.

Now let’s delete that import again.

Let’s go back to the cylinder file.

Except this time, we will import it as a background mesh.

You will see that this time,

only the green cylinder has been imported

as it was the only solid recognized as a mesh.

If the mesh is a structure,

it can be used with the sketch 2D or sketch 3D commands

as a snapping object while drawing.

If the imported file is an open surface,

such as a topography,

it is best to import the mesh surface as a background mesh

in either the STL, DWG or DXF file format.

Let’s open the ground surface DWG file as an example,

we will need to remap the axes like we have done previously.

Now, we can right-click on the mesh

under the background’s tree and choose Fit to Surface.

This opens the fit to surface window,

which will be discussed in the next tutorial video

of this series.

The last import feature we will discuss

in this video is the import profile.

Let’s switch to a new Build3D project,

which already has a geological model imported via Central.

For more information on importing from Central,

please refer to the previous video of this importing series.

Now, let’s say we wanted to add a tailings dam design

that was created in a third party software

to review the potential poor water pressure conditions

of the underlying foundation following construction.

To add this design to our 3D model,

we will go to Import Profile.

Here, we will choose the 2D cross-section design

that was created in a CAD software.

Once imported, we will need to ensure

that we remap the axes and insertion point

to our desired location.

Once the cross-section is inserted to our desired location,

we can now convert this profile to a solid

by extruding it across the geological model.

If we assume that nothing was removed

from the original topography

for the construction of the tailings dam,

we can cut the solids using the foundation materials.

We have now reached the end of the session.

Next time, we will discuss the fit to surface feature

in Build3D.

Thank you.