As noted in the community Duke3D HRP thread, these assets were shared so others could "generate normal maps".
Locate your autoload or highres directory in your EDuke32 installation. 4182.rar
texture 4182 { pal 0 { file "highres/textures/4182_diffuse.png" } } normal 4182 { file "highres/textures/4182_norm.png" } specular 4182 { file "highres/textures/4182_spec.png" } Use code with caution. Copied to clipboard As noted in the community Duke3D HRP thread,
The archive typically contains high-resolution textures or raw source files for tile #4182, which corresponds to specific architectural or decorative elements in the Duke3D engine. 4182.rar