Discrete Measurement Targets Were Frequently Utilized in Image-Based Methods on the Specimen's Surface to Monitor the Soil Specimen during Triaxial Testing. However, the Required Density of Measurement Targets that Should Be Used in Triaxial Testing to Achieve Highly Accurate Volume Measurement Has Not Been Investigated. to overcome This Limitation, This Paper Presents a Parametric Study to Determine the Optimum Target/point Densities to Be Utilized on the Triaxial Soil Specimen Surface to Achieve the Desired Level of Volume Measurement Accuracy in Image-Based Methods. LiDAR Scanning Was Applied to Establish the "Ground Truth" Volume of the Specimen. the Effects of Deformation and Failure Modes Were Investigated by Calculating the Volume Measurement Accuracy at Different Strain Levels and for Different Undisturbed Soil Specimens of Clay and Sand with Silt. an Interpolation Method Was Proposed to Increase the Number of Discrete Targets Representing the Triaxial Specimen's Surface. the Analysis Results Show that a Higher Target Density is Required at a Larger Strain. Also, Adding the Number of Interpolation Points Can Only Increase the Accuracy to a Certain Level. as the Volume Measurement Accuracy Was Different for Each of the Clay and Sand with Silt Specimens, the Non-Uniform Deformation, and Failure Mode of the Specimen Can Affect the Required Optimum Density of Discrete Measurement Targets. in Conclusion, It is Recommended to Choose the Optimum Density of Targets based on the Accuracy Requirement, the Maximum Soil Deformation Level, and the Expected Failure Mode of the Specimen.