Due to the complex and unstructured nature of the intestine, 3D reconstruction and visual navigation are imperative for clinical endoscopists performing the skill-intensive colonoscopy. Unsupervised 3D reconstruction methods, as a mainstream paradigm in auto-driving scenarios, exploit warping loss to predict 6-DOF pose and depth information jointly. However, owing to illumination inconsistency, repeated texture regions, and non-Lambertian reflection, the geometry warping constraint cannot be efficiently applied to the colonic environment.