# A Combinatorial Solution to Point Symbol Recognition

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## Abstract

**:**

## 1. Introduction

## 2. Related Works

#### 2.1. Point Symbols in the Topographic Map

#### 2.2. Application of Deep Learning in Object Recognition

## 3. Method

Algorithm Framework Procedure of Point Symbol Recognition |

Step 1 Prescreening the topographic maps. |

Step 1.1 The topographic map is processed to extract the black sub-layouts. |

Step 1.2 Based on the method of judging the minimum bounding rectangle, the connected region of suspected point symbols should be obtained. |

Step 2 Training the model. |

Step 2.1 Pretraining the AlexNet networks based on MNIST database by transfer learning to obtain the pretraining model. |

Step 2.2 Pretaining the pretraining model based on the point-symbols data to obtain the final model. |

Step 3 Recognition of the point-symbols. |

The test images of point symbols input the final model to test the recognition accuracy. |

#### 3.1. The Prescreen Based on the Characteristics of Point Symbols

#### 3.2. The Point Symbol Recognition Based on AlexNet

## 4. Experiment Analysis and Results

#### 4.1. The Point Symbols Dataset

#### 4.2. The Comparison of Algorithms

#### 4.2.1. The Prescreening of Point Symbols

#### 4.2.2. The Recognition of Point Symbols

#### 4.3. Runtime Analysis

## 5. Conclusions

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 2.**The figure shows the comparison of map changes after color segmentation, as follows: (

**a**) the original image of the topography map; (

**b**) the sub-layout images of the topography map.

**Figure 3.**This figure plays the comparison of map changes after prescreening. They are listed as (

**a**) description of figure after binarization; (

**b**) description of the figure that extracts the black sub-layouts and eliminates the noise.

**Figure 9.**The prescreening of point symbols is presented in the figure. They are listed as (

**a**) the original map; (

**b**) the grid pattern; (

**c**) the connected region pattern with prescreening; (

**d**) the connected region pattern.

Category | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
---|---|---|---|---|---|---|---|---|---|

Symbols | |||||||||

Number | 250 | 205 | 200 | 238 | 240 | 243 | 204 | 219 | 212 |

Category | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
---|---|---|---|---|---|---|---|---|---|

Ration | 1 | 1 | 0.935 | 0.963 | 0.902 | 0.932 | 0.984 | 0.896 | 0.82 |

LeNet (Pre-Trained) | VGG-16 (Pre-Trained) | AlexNet (Not Pre-Trained) | AlexNet (Pre-Trained) | BP Networks | SLS-GH | |
---|---|---|---|---|---|---|

The 1st test image | 93.5 | 90.61 | 96.76 | 98.85 | 89.65 | 98.57 |

The 2nd test image | 90.33 | 95.32 | 96.76 | 98.97 | 83.68 | 98.28 |

The 3rd test image | 92.87 | 94.35 | 95.68 | 99.56 | 89.45 | 98.56 |

The 4th test image | 92.56 | 96.61 | 94.84 | 98.49 | 81.23 | 97.65 |

The 5th test image | 91.32 | 93.89 | 95.15 | 98.96 | 83.12 | 97.76 |

Average | 92.12 | 94.45 | 95.84 | 98.97 | 85.43 | 98.16 |

AlexNet—Not Pre-Trained (ms) | BP Networks (ms) | SLS-GH (ms) | |
---|---|---|---|

The 1st test image | 256 | 564 | 890 |

The 2nd> test image | 196 | 456 | 501 |

The 3rd test image | 396 | 1064 | 1460 |

The 4th test image | 231 | 256 | 328 |

The 5th test image | 485 | 536 | 689 |

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**MDPI and ACS Style**

Quan, Y.; Shi, Y.; Miao, Q.; Qi, Y. A Combinatorial Solution to Point Symbol Recognition. *Sensors* **2018**, *18*, 3403.
https://doi.org/10.3390/s18103403

**AMA Style**

Quan Y, Shi Y, Miao Q, Qi Y. A Combinatorial Solution to Point Symbol Recognition. *Sensors*. 2018; 18(10):3403.
https://doi.org/10.3390/s18103403

**Chicago/Turabian Style**

Quan, Yining, Yuanyuan Shi, Qiguang Miao, and Yutao Qi. 2018. "A Combinatorial Solution to Point Symbol Recognition" *Sensors* 18, no. 10: 3403.
https://doi.org/10.3390/s18103403