DIRSIG

As many of you may have read in past posts by Niek , we have been using the Blender software heavily in the construction of scenes so they can be ingested into DIRSIG . While we have many Blender tools that work in the editing and exporting of existing scenes, they only utilize a small subset of features that exist in Blender. Blender can be viewed as the vi (or emacs) of the 3D animation world which means it can be very powerful but at times opaque to the newly initiated. After paying our dues in the apprenticeship of Blender knowledgedom, we wanted to make accessible to DIRSIG users the capabilities that have made Blender the de facto standard of the 3D animation domain. In an ongoing project that addresses the need of data sets for training machine learning algorithms and assessing the performance of target detection/exploitation algorithms, DIRS has focused on implementing tools for producing numerous instantiation of simulated scenes. Blender has been an integral part ...

In a previous post, we discussed the advantages of using OBJ files in DIRSIG. This tutorial video shows how Blender can assign DIRSIG materials to an OBJ geometry mesh.  Basic familiarity with Blender is a prerequisite. Attributing an OBJ with DIRSIG materials (video) The idea is simple: in the OBJ file, the "use material" ( usemtl ) string will specify a DIRSIG material id rather than just an arbitrary material name.  The OBJ's "material library" ( mtllib ) string is ignored by DIRSIG.

When we first started on the DIRSIG model in the late 1980s, 3D computer graphics was still in its infancy. At the time, standard file formats for 3D geometry were still being established. In addition, the DIRSIG model had the need for a specific set of per-facet attributes (material ID, thickness, override temperature, etc.) that are still somewhat unique in the 3D modeling community. As a result, the DIRSIG specific Geometric Database (GDB) format was created and is still used to this day. In the mean time, a variety of 3D geometry file formats have become widely used. Although the GDB format serves our needs well, it requires the user to translate the 3D geometry assets from other formats in order to use them with DIRSIG. Lately we have been experimenting with using the Alias/Wavefront OBJ file format as a possible replacement for GDB. The important features of the OBJ format are: It is widely supported by 3D geometry authoring tools (Rhino, SketchUp, Blender, etc.). It supports per...