gprMaxLogo toolbox

Fig. 85 The gprMax version 4 resonant-field wordmark.

The version 4 wordmark preserves the physical idea behind the original gprMax logo. The lettering is not filled with a decorative texture: the colours are generated by an FDTD simulation performed by gprMax itself.

Physical construction

The logo is a 2D TMz model. A 1.0 m by 0.5 m plane is first filled with PEC, then the gprMax glyphs are carved out as free space. The lettering uses IBM Plex Sans Bold without additional tracking. Each isolated glyph therefore forms a small electromagnetic cavity; the electric field is zero in the PEC surrounding the letters.

Eight z-polarised Hertzian line sources excite the cavities with continuous 10 GHz or 12 GHz sinusoidal waveforms. Their relative amplitudes are calibrated on the final grid to give comparable RMS field strength in each glyph. The official model has a 0.083333 mm spatial step and 12000 by 6000 cells. Its Ez field is sampled at 10 ns. No PML is needed because every free-space cavity is enclosed by PEC.

The source waveform is a line current \(I\) in amperes. gprMax deposits the electric-current density

\[J_z = \frac{I\,\Delta z}{\Delta x\,\Delta y\,\Delta z} = \frac{I}{\Delta x\,\Delta y}.\]

The spatial grid, source amplitudes, and all other simulation parameters are fixed as part of the authoritative model.

Fig. 86 The free-space glyph mask before the field simulation. White identifies the glyph cavities and black identifies the surrounding PEC plane.

Rendering and colours

The renderer takes the magnitude of Ez, normalises it by the 99.5th percentile inside the glyphs, and applies a power-law colour mapping. The scale retains the established gprMax purple (#55037f), with indigo and blue for weaker fields and magenta and pink for stronger fields. The PEC background is transparent, so the wordmark works on both light and dark pages.

The prebuilt asset collection contains transparent, white-background, and dark-background PNGs. Use the transparent version where possible, preserve the wordmark aspect ratio, and retain the gprMax capitalisation.

• 2048 px transparent PNG

• 1024 px transparent PNG

• 512 px transparent PNG

• Asset manifest

Reproducing the logo

The complete model, bundled font and licence, rendering tools, standard exports, and detailed reproduction instructions are included in the gprMaxLogo README.

Generate the model from the repository root with:

$ python gprMax/toolboxes/gprMaxLogo/logo_model.py

The production case contains 72 million cells and produces an approximately 1.7 GB raw field snapshot, so a suitable GPU is recommended. The snapshot is not distributed; the compact input model and generated assets are. After the simulation, render_logo.py creates the 10000-pixel transparent master and export_assets.py downsamples it to the standard screen and print sizes. Every derivative therefore contains the same field pattern and relative colour balance.