3D objects need to look like they exist in the real world. This is especially true for common use cases like architectural renderings and architectural visualization, which can turn a basic floor plan into a clear vision of what's to come.
Realistic light sources make all the difference in turning a collection of polygonal objects into a space that looks real. But 3D artists generally don't paint in light or shadows themselves. Instead, a 3D scene includes settings for the direction, intensity, and type of light source that illuminates the various objects.
Textures created with the Adobe Substance 3D toolset respect by default physically based rendering (PBR) principles, and thus will appear realistic in all lighting conditions. So a wooden table will still appear to be wooden whether it’s placed on a sunny terrace, indoors, or even deep underground.
Notably, some surfaces and materials bend light or interact with it in distinctive ways. Glass and ice are translucent, so they reflect and refract light. Light plays on the surface of water and other liquids, and prisms make tiny rainbows when light hits them just so. A scene that is accurately textured, and artfully lit, can appear compelling and dramatic.