Early culling of the invisible geometric primitives in a complex scene is valuable for efficiency in the conventional rendering pipeline. This may reduce the number of geometric primitives that will be processed in the rest of the pipeline. In this paper, we propose a conservative six degrees of freedom (DoF) incremental occlusion culling method called Delta-Horizon (Delta H). Delta H method is based on constructing an occlusion horizon (OH), which is a set of connected lines passing just above all visible primitives, for culling the invisible primitives beyond. Utilizing the coherence of occluders enables the incremental update of OH in consecutive frames. Although Delta H method may work in image space, we utilize polar coordinates and build OH in object space. This not only facilitates a quick update of OH, but also overcomes the drawbacks of previous OH methods such as viewing in six DoF, occlusion culling within up-to-360-degree viewing frustums in one pass and camera zooming without additional cost.