# An Adaptive Simplification Method for Coastlines Using a Skeleton Line “Bridge” Double Direction Buffering Algorithm

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## Abstract

**:**

## 1. Introduction

## 2. Bidirectional Buffer Zone Method

#### 2.1. Basic Principles

#### 2.2. Existing Flaws

## 3. Skeleton Line “Bridging” Bidirectional Buffer Zone

#### 3.1. Basic Philosophy

#### 3.2. Critical Steps

#### 3.2.1. Determination of Buffer Distance under Visual Constraints

#### 3.2.2. Shoreline Skeleton Line Binary Tree Construction

#### 3.2.3. “Source Tracing” Algorithm Extracts “Bridging” Skeleton Lines

#### 3.2.4. “Bridging” of the Original Result Line and Local Details

## 4. Experiments and Analysis

#### 4.1. Evaluation of the Effectiveness of the Methodology

#### 4.2. Methods Comparative Analysis and Evaluation

#### 4.2.1. Qualitative Assessment

#### 4.2.2. Quantitative Assessment

## 5. Conclusions

- (1)
- The original bidirectional buffer zone method tends to have an excessive simplification scale when dealing with bottleneck areas, as it lacks a mechanism to handle these regions. In this paper, the coastline is adaptively simplified by extracting “bridging” skeleton lines, constructing a visual buffer zone based on the “bridging” skeleton lines, and “bridging” the simplified result line of the original bidirectional buffer zone with local details. Additionally, it can adaptively exaggerate and represent local narrow areas. The simplification quality of this method is generally comparable to that of the constrained Delaunay triangulation method.
- (2)
- Compared to existing methods, the proposed method in this paper has higher simplification accuracy, closely follows the original coastline, and does not contain any non-visible detail parts after simplification, meeting the relevant requirements of the “Standard for Nautical Chart Production”.

## Author Contributions

## Funding

## Data Availability Statement

## Conflicts of Interest

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**Figure 3.**The schematic diagram of the proposed method. (

**a**) Out-of-buffer transformations; (

**b**) Transformations within buffers; (

**c**) Extracts the “Bridged” skeleton line and its visual buffer zone; (

**d**) “Bottleneck” areas Exaggerated.

Scheme | 1:500,000 | 1:750,000 | 1:1,000,000 | 1:1,250,000 | ||||
---|---|---|---|---|---|---|---|---|

Forward | Negative | Forward | Negative | Forward | Negative | Forward | Negative | |

Douglas–Peucker | 1624.62 | 2102.67 | 1723.29 | 3702.88 | 1857.67 | 4962.91 | 2022.38 | 5365.98 |

Bidirectional buffers | 1937.69 | 0.0 | 5222.12 | 0.0 | 5766.89 | 0.0 | 6439.2 | 0.0 |

Triangulation method | 690.48 | 77.54 | 2315.01 | 163.20 | 4180.96 | 164.87 | 5222.37 | 428.33 |

This article | 168.09 | 30.74 | 957.40 | 201.45 | 2221.93 | 244.39 | 3248.87 | 359.99 |

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## Share and Cite

**MDPI and ACS Style**

Tang, L.; Zhang, L.; Dong, J.; Wei, H.; Wei, S.
An Adaptive Simplification Method for Coastlines Using a Skeleton Line “Bridge” Double Direction Buffering Algorithm. *ISPRS Int. J. Geo-Inf.* **2024**, *13*, 155.
https://doi.org/10.3390/ijgi13050155

**AMA Style**

Tang L, Zhang L, Dong J, Wei H, Wei S.
An Adaptive Simplification Method for Coastlines Using a Skeleton Line “Bridge” Double Direction Buffering Algorithm. *ISPRS International Journal of Geo-Information*. 2024; 13(5):155.
https://doi.org/10.3390/ijgi13050155

**Chicago/Turabian Style**

Tang, Lulu, Lihua Zhang, Jian Dong, Hongcheng Wei, and Shuai Wei.
2024. "An Adaptive Simplification Method for Coastlines Using a Skeleton Line “Bridge” Double Direction Buffering Algorithm" *ISPRS International Journal of Geo-Information* 13, no. 5: 155.
https://doi.org/10.3390/ijgi13050155