STL (stereo-lithography) files are the pathway to import information from SolidWorks and other three-dimensional CAD programs into MetaMesh. The method has proved reliable and is applied with increasing frequency. For some time Geometer has had the capability to display STL objects referenced in MetaMesh scripts (FileName.MIN). Information from STL files is automatically loaded with the script. It is also possible to load additional STL files and use them to define new parts in an assembly.
I recently had a consulting job where a customer sent several STL files to define the parts of an electron gun. Before starting, I wanted to check the dimensions and positions of the parts to fit them into my assembly. Geometer was not particularly helpful for this function. I had to use the command Show STL file parameters for all parts to find their extents in three-dimensional space and then set up a dummy solution volume with an air region that enclosed the STL parts. One alternative was to use a three-dimensional viewer like SolidView or DeskArtes Expert, available for download at
http://www.solidview.com
http://www.deskartes.fi
The problems were that 1) measurement tools were inactive in the free versions and 2) the programs lacked the quantitative orthographic view capabilities of Geometer.
I decided it was time to add a full-featured 3D viewer for STL files to Geometer. The program already had the requisite OpenGL display machinery, so the task was straightforward. The STL Viewer is called from the Geometer main menu. In the Viewer menu, you can load up to 50 STL files. The program automatically adjusts the default view to encompass the full assembly. The first picture below shows a screenshot for the perspective display mode, the standard 3D display of SolidView and DeskArtes Expert. You can move about freely through the solution space with interactive mouse controls. You can set the display mode for individual models to solid or wireframe or suppress their display. You can also add cutplanes to individual models to probe inside an object.
The second picture shows the orthographic view unique to Geometer. Three-dimensional representations of models (with lighting effects) are shown in an orthographic projection normal to a chosen coordinate axis. Grids with automatic or user-defined intervals may be included. You can zoom in on details and use the mouse to get accurate coordinates of features.
In summary, the STL Viewer is great help in setting up MetaMesh scripts with STL objects. With its ease of use and powerful features, it also make an attractive standalone viewer for three-dimensional objects. The STL Viewer will be included in Version 3.0 of Geometer to be released October 1.
