# Coverage Path Planning using Path Primitive Sampling and Primitive Coverage Graph for Visual Inspection

## TL;DR

This paper introduces a novel path planning method for UAV-based visual inspection that directly samples inspection paths using path primitives and a Primitive Coverage Graph, improving efficiency in complex 3D environments.

## Contribution

It proposes a new planning approach that directly samples inspection paths with a Primitive Coverage Graph, bypassing traditional viewpoint optimization.

## Key findings

- Effective in complex 3D environments
- Validated through simulation and field tests
- Achieves comprehensive surface coverage

## Abstract

Planning the path to gather the surface information of the target objects is crucial to improve the efficiency of and reduce the overall cost, for visual inspection applications with Unmanned Aerial Vehicles (UAVs). Coverage Path Planning (CPP) problem is often formulated for these inspection applications because of the coverage requirement. Traditionally, researchers usually plan and optimize the viewpoints to capture the surface information first, and then optimize the path to visit the selected viewpoints. In this paper, we propose a novel planning method to directly sample and plan the inspection path for a camera-equipped UAV to acquire visual and geometric information of the target structures as a video stream setting in complex 3D environment. The proposed planning method first generates via-points and path primitives around the target object by using sampling methods based on voxel dilation and subtraction. A novel Primitive Coverage Graph (PCG) is then proposed to encode the topological information, flying distances, and visibility information, with the sampled via-points and path primitives. Finally graph search is performed to find the resultant path in the PCG to complete the inspection task with the coverage requirements. The effectiveness of the proposed method is demonstrated through simulation and field tests in this paper.