Accuracy is an important measure of system performance and remains a challenge in 3D range gated reconstruction despite the advancement in laser and sensor technology. The weighted average model that is commonly used for range estimation is heavily influenced by the intensity variation due to various factors. Accuracy improvement in term of range estimation is therefore important to fully optimise the system performance. In this paper, a 3D range gated reconstruction model is derived based on the operating principles of range gated imaging and time slicing reconstruction, fundamental of radiant energy, Laser Detection And Ranging (LADAR), and Bidirectional Reflection Distribution Function (BRDF). Accordingly, a new range estimation model is proposed to alleviate the effects induced by distance, target reflection, and range distortion. From the experimental results, the proposed model outperforms the conventional weighted average model to improve the range estimation for better 3D reconstruction. The outcome demonstrated is of interest to various laser ranging applications and can be a reference for future works.

This paper performs an experimental investigation on the TOF imaging profile which strongly influences the quality of reconstruction to accomplish accurate range sensing. From our analysis, the reflected intensity profile recorded appears to deviate from Gaussian model which is commonly assumed and can be perceived as a mixture of noises and actual reflected signal. Noise-weighted Average range calculation is therefore proposed to alleviate noise influence based on the signal detection threshold and system noises. From our experimental result, this alternative range solution demonstrates better accuracy as compared to the conventional weighted average method and proven as a para-axial correction to improve range reconstruction in 3D gated imaging system.

Range determination has crucial dependency of intensity over distance due to the fact that output of a range gated system is the reflectivity and range information expressed in term of intensity. From our experimental study, the analyzed trend line of reflected intensity versus range agrees with the theoretical model where it underlies an inverse range-squared dependency. Considering the energy attenuation factor for a better three-dimensional (3D) solution, a range compensation model is derived based on time slicing technique to compensate the effect imposed by distance beyond an optimum range. A range gated imaging system with pulse profile feedback is proposed in order to apply the range compensation model. Experimental results show noticeable improvement as compared to the conventional weighted average method for reflected laser pulse data across different ranges and 3D surface reconstruction using the proposed range compensation model.

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