A short survey is given of various techniques of 3D visualization of voids and other structural defects that are inherently present in thermally spray structures. It is proven that the only condition for visualization is possibility to set up a distinguishable threshold based on the gray scale of the microscopical image of the structure. Segmented images are then further processed by commercial software for image analysis, animations and anaglyph files creation. Several softwares were applied and combined, such as Lucia, Voxblast, Amira and Voxler. The visualization technique was demonstrated on a ceramic plasma sprayed coating, where two kinds of voids – semi-globular pores and large interlamellar pores could be separated. Similarly, this visualization technique can be used to distinguish between pores and oxide particles in case of metallic coatings. The visualization is done in a real Cartesian space without any transformation. The results can be useful mainly for: a) teaching to get a better insight into the microstructure of thermally sprayed coatings, b) research, where in combination with mathematical quantification the visualized structure can show important distinctions between coatings sprayed by different techniques and with variety of process parameters.