# Influence of Material on the Density of a Point Cloud Created Using a Structured-Light 3D Scanner
## 6 Conclusions
### RQ2: How Can the Material Surface Be Easily Treated for Higher Point Cloud Density?  
Materials classified as having very fine elements, glossy materials, and transparent materials had to be treated to achieve the required point cloud density values in the sample area. However, according to the results, we can say that the treatments made to eliminate undesirable properties had a positive effect on the average value of the point cloud density relative to the sample area.  
The solution for glossy materials could be to decrease their reflectivity. The solution for transparent materials could be to decrease their transparency. For the experiments, we used chalk spray and dry shampoo to achieve this.  
For materials containing very fine elements, the solution could be to make the surface more compact. Although the need did not successfully reach the required threshold in any measurement, the density of the point cloud improved significantly. This finding could be helpful, for example, in human hair [32].  
Since the need could not be adjusted as easily as the fabric, it was at least supported by board material--planks. As a result, the gaps between the individual stalks have become smaller and the surface more uniform and compact. Although it was not possible to scan the entire surface, even such a surface treatment proved to be effective and was able to increase the total average density of a point cloud from 75,709 to 119,204 points per sample area, which is about a 50% increase.  
The surface treatments were used to improve the scannability of materials. It can be expected that the application of suggested surface treatments is not suitable for all objects and/or materials. It needs to be taken into consideration whether intended treatment may harm the object and/or material, and/or cause permanent damage to the object and/or material. The influence of the suggested surface treatments on scanned objects and/or materials is not the subject of this article. Each intended case of using the suggested surface treatments needs to be considered individually to avoid object deterioration and/or material deterioration, as is stated in Applicability of Surface Treatments in Practice subsection of Section 5.  
RQ3: Can the Data Acquisition Process Be More Efficient with the Knowledge of the Appropriate Surface Treatment?  
Overall, the results show that material properties can have a demonstrably large effect on the density of the point cloud, with the presence of fine elements and transparency having the greatest effect. To a lesser extent, gloss also affected it. It was also shown that the treatments made had a positive effect on the measurement results in all cases and in some cases enabled the complete scanning of materials. The measurement results also show that even materials that are adjacent to each other could interact with each other.  
The results of the research show for which materials it is suitable to use structured-light 3D scanning measurement under the given requirements for the density of a point cloud intended for the creation of a digital model of building object. In practice, this means that during reconnaissance before the measurement itself, it is possible to estimate, based on these results, if the structured-light measurement method is suitable for particular parts of the measured object according to the type of its surface material.  
From the results, it can be expected that the knowledge gained from this research can speed up the process of passporting existing buildings.