Links 27/8/2020: Kubernetes 1.19, 2020 Linux Kernel History Report, Linux Foundation Board Member From Microsoft Liaises With Microsoft Tim

Links 27/8/2020: Kubernetes 1.19, 2020 Linux Kernel History Report, Linux Foundation Board Member From Microsoft Liaises With Microsoft Tim

In this followup to our coverage of the release of gnuplot 5.4, we look more deeply at one of the new features: voxel plots. We only briefly touched on these plots in that article, but they are the most conspicuous addition in this release of the free-software graphing tool. Voxel plotting provides multiple ways to visualize 3D data, so it is worth looking at this new plot type in more detail.


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The first six lines of the script set the ranges of the display bounding box, the angle of view, the position of the bottom plane, and set the borders to surround the box on all sides. The next line, beginning with $charges, defines a “data block” consisting of the following two lines. Each line contains x, y, z, coordinates and, in the fourth column, the magnitude of the charge. The final command, broken over two lines, plots the two charges using their positions, extracted with the using 1:2:3 piece, and the charge value from the fourth column, extracted with the :4. This value is used to decide which colors the plotted points should be, by mapping the value onto the color palette, which is what the “linecolor palette” tells gnuplot to do. The other clauses set the pointsize to be five character widths and the pointtype to a circle (7).


Next, we will make a graph of the 3D structure of the potential field around these two charges. For this, we turn to the voxel grid. Just as a 2D image, such as a photograph, is a rectangular array of pixels, data in 3D can be represented as a 3D rectangular array of voxels, or volume pixels. Each voxel has x, y, and z coordinates, and a numerical value attached to it, so the voxel grid can repr ..

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