Final answer:
Campin, Van Eyck, and Van Der Weyden showed similarities in their work through their realistic portrayals, characterized by accurate, detailed depictions of light, texture, and depth, rather than advancements in watercolor or fresco techniques.
Step-by-step explanation:
Artists Robert Campin, Jan Van Eyck, and Rogier Van Der Weyden, all prominent figures of the Early Netherlandish period, primarily demonstrated similarities in their work through their realistic portrayals. Unlike advancements in watercolor technique or fresco technique, which weren't their main focus, they are known for their attention to detail, accurate and meticulous depictions of light and texture, and overall realism. Their works often feature profound depth and richness, leading to an almost photographic quality that characterizes their style.
Learn more about Early Netherlandish Artists