I. INTRODUCTION  
II. PROBLEM DEFINITION  
III. CHALLENGES  
IV. CATEGORIES  
V. OPTIMIZATION-BASED REGISTRATION METHODS  
VI. FEATURE-LEARNING METHODS FOR REGISTRATION  
VII. END-TO-END LEARNING-BASED REGISTRATION  
VIII. CROSS-SOURCE POINT CLOUD REGISTRATION  
IX. CONNECTIONS BETWEEN OPTIMIZATION-BASED METHODS AND DEEP LEARNING  
X. EVALUATIONS  
XI. APPLICATIONS  
XII. OPEN QUESTIONS AND FUTURE DIRECTION  
XIII. CONCLUSION