Programs for Linux:

• blender - 3D content creation suite
• gimp - powerful image editor, free variant ala Photoshop
• gnuplot - interactive plotting of 2D functions and 3D surfaces
• inkscape - object oriented drawing program for SVG graphics, can also edit PDF
• xfig - object-oriented drawing program under X11
• xv - View, edit and convert images of different image formats

Programs for macOS:

• inkscape
• scribus