Examples of the H I emission and filamentary structures toward the l and υ_LSR ranges with predominantly horizontal filamentary structures. The top image in each panel corresponds to the H I emission intensity in three velocity-channel maps presented in red, green, and blue colors. The bottom image corresponds to the second eigenvalue of the Hessian matrix, λ₋, which highlights the filamentary structures in each velocity-channel map. The white disk in the lower right corner corresponds to the size of the derivative kernel used to calculate the Hessian matrix.