3D comparison

Command: 3DCOMPARE.

You can compare two 3D models, for example 3D solids and surfaces stored in 2 DWG files, including models imported in BricsCAD from other file formats. The tool can process large models and reports the differences in the Mechanical Browser. Multiple visualization modes are supported.

Definitions

A 3D model is a DWG file with one or more 3D solids or surfaces. When comparing two 3D models, BricsCAD first tries to automatically align them in 3D space to obtain the maximal similarity. Next, all faces of these 3D solids and surfaces are compared geometrically with a given tolerance. If for every face in the first file an equal face in the second file exists and vice versa, such models are considered as equal. However, if for a particular face in one file there is no equal face found in another file, or if only part of this face is equal to a part of a face in the other file, a difference is detected. Therefore, a difference is a full face or a part of a face of a 3D solid or a surface, for which there are no equal parts of full faces found in the other file. Two or more differences are grouped together if they are geometrically adjacent to each other.

A difference node is created in the Mechanical Browser for every group of adjacent differences. If you expand this node, you can see the particular differences it consists of. When you select the difference in the Mechanical Browser, the corresponding feature is highlighted in the drawing.

Toolbars

You can access the 3D Comparison procedure by using the tools on the Compare 3D panel on the Tools tab.

Visualization

Use the 3DCOMPARE command to create a new DWG document named Compare_<File_1>_<File_2>.dwg. The compared models are attached as external references to this drawing, A special layout named Comparison is created automatically with 2 viewports, one for each drawing, illustrating the differences between the drawings by using colors.

The display is controlled via the 3DCOMPAREMODE system variable. If the value of 3DCOMPAREMODE is different from 0 (zero), the corresponding model becomes semi-transparent, while the differences are displayed using different colors. Each difference is painted in its individual color. You can zoom in on a particular difference using the Mechanical Browser context menu.

To display the differences:
  1. Click the Left Viewport tool button () and/or the Right Viewport tool button ().
  2. Double-click in one of the viewports.

  3. Use the mouse/keyboard shortcuts to manipulate the display.

    Example: Zoom in/out or rotate.

    The display in the other viewport is synchronized automatically. This allows you to compare the same part in both models in detail.

As an alternative, you can:

Click the Single tool button ().

The differences in model space are displayed.