3D objects in Blender are often referred to as meshes. Each mesh is fundamentally composed of vertices, lines and faces. A vertex is a singularity construct—it has no volume associated with it—and is defined by its X–Y–Z coordinates in the global 3D view port. These coordinates can be transformed to another coordinate system or reference frame. Vertices can be connected via lines and a closed loop of vertices and lines can form the boundary for a solid, flat surface called a face.
A mesh has geometric properties that include an origin about which the object can rotate and/or revolve. The individual vertices, lines and faces can be edited in Mesh Edit mode, accessed via the Mode Selection drop-down menu or the TAB key (figure ). Each mesh has a selection mode via those vertices, lines and faces.
A base mesh can be created by Add → Mesh from the menu at the top of the screen. The basic meshes are shown in figure . These can be deformed, changed and extended to fit the scientific visualization required.
Figure 3.1. Blender mesh examples that form the basis of data containers and grid constructs in scientific visualization. These basic shapes—a cube, cone, UV-sphere, torus, cylinder and icosphere—can be manipulated in the Blender 3D view port.
We can further manipulate the individual elements of the mesh in a number of ways. This can help the user precisely position the scene elements and data objects of a visualization.
Figure 3.2. Blender Mesh Edit mode is selected and the vertex, line and face mode buttons are shown. This allows the user to manipulate individual parts of a mesh object.
Textures can be applied in a variety of scenarios. 2D textures can be utilized to give a face a more realistic surface appearance, apply mapping data, and change the visibility and color of the data. Bump mapping can also be applied to meshes to simulate 3D surfaces. This has important applications in increasing the speed of rendering times with lower polygon counts . 2D materials and textures can be applied to single faces or an entire mesh object in a variety of projections in the UV-plane. A orthographic projection map of the Earth is shown in figure and .
Figure 3.3. This view shows the set-up for projecting a 2D map of the Earth onto a UV-sphere.
Figure 3.4. Earth map projection with images from . Several layers are presented here in a final composite, including a day and night side maps of the Earth and an atmospheric layer.
We can use the following procedure to project the map onto a sphere. This requires marking a seam on the sphere where the object will be separated. A projection of the mesh can then be matched to an image or a map.
Figure 3.5. In Mesh Edit mode (TAB key), a seam can be added with CTRL–E. In this particular example we are marking the seam along a meridian.
Figure 3.6. With the seam on the meridian properly marked a map projection can now be applied using UV Mapping.
For 3D materials and textures, Blender can apply halos to data points or render data cubes as transparent volumes. Halo textures can be applied to vertices and are useful for creating 3D scatter plots.
We will use the vertices of a 3D mesh as our sample X, Y, Z data and texture those points with a halo.
Figure 3.7. The halo material can be applied to illuminate individual vertices in a scatter plot or catalog. These small Gaussian spheres have size, illumination and color properties that can be adjusted.
With the same icosphere mesh object (or any mesh), a 3D wireframe object can be created. These are useful for creating background grids in 3D scatter plots. Simply change the material to ‘Wire’ and the shading emission to 1.0 (figure ).
Figure 3.8. A wire material can be applied to a mesh. This is useful in creating grids and bounding boxes for visualizations.
 Blinn J F 1978 Simulation of wrinkled surfaces SIGGRAPH Comput. Graph.
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