# A Survey of Low-Cost 3D Laser Scanning Technology
## 5 Discussion  
### The Definition of Low Cost  
In this paper, we focus on low-cost 3D laser scanning technology, of which low cost is the core argument.  
The definition of low cost can be divided into two aspects. First, low cost is a relative concept. For a 3D laser scanner, if its price is significantly lower than that of similar products, and it hits the bottom of the price of this type of products, then it is low-cost. As a 3D laser scanner, the cost of a moving 2D LiDAR is significantly lower than that of commercial 3D laser scanners, so it is low-cost. Although low cost is bound to be accompanied by insufficient performance, in many applications, excess performance is unnecessary, and cost reduction is a top priority.  
Second, low-cost can be understood as consumer-grade, which is used to describe products that can be affordable by the public. The current dilemma of commercial 3D laser scanners is that they are not consumer-grade yet. In China, the price of a private car purchased by an ordinary household is between CNY 50,000 (equivalent to USD 7640) and CNY 200,000 (equivalent to USD 30,560). The 3D LiDAR VLP-16 (Puck) produced by Velodyne is priced at CNY 35,000 (equivalent to USD 5348), HDL-32E is priced at CNY 378,600 (equivalent to USD 58,064), and HDL-64E is priced at CNY 680,000 (equivalent to USD 103,904)--which is about the price of a house in a medium-sized city of China. As a necessary sensor for autonomous driving technology, 3D LiDAR is even more expensive than a car. This phenomenon is widespread, which limits the popularization of autonomous driving technology, making it impossible for private cars with autonomous driving technology to enter millions of households.  
Although commercial 3D laser scanners are generally not consumer-grade, some 2D LiDARs have reached the consumer-grade level. For example, the 2D LiDAR RPLIDAR A1 produced by Slantec is priced at CNY 500 (equivalent to USD 76), RPLIDAR A2 is priced at CNY 1900 (equivalent to USD 290), and RPLIDAR A3 is priced at CNY 4095 (equivalent to USD 626). The prices of these products are not higher than the price of a mobile phone, for ordinary households, they are affordable.  
In recent years, sweeping robots have gradually become popular, and they have occupied a place in the home appliance market. Most of them are based on 2D laser SLAM technology; the 2D LiDARs mounted on them have reached the consumer-grade level, so they are low-cost, for the sweeping robots equipped with 2D LiDARs have already been affordable by ordinary households.  
The above-mentioned sweeping robot can only build 2D maps of the environment. Limited by their environment detecting ability, their functions are single. To make a home service robot more intelligent and perform more complex tasks, low-cost 3D laser scanning technology is necessary. Figure 14 shows the prototype we built recently. In this prototype, 2D LiDAR RPLIDAR A1 LiDAR produced by Slantec is used, it is rotated by an integrated closed-loop stepper motor.  
The total cost of the 3D laser scanner shown in Figure 14 is no more than CNY 2000 (equivalent to USD 306). Although it is cheap to build, it can perform basic 3D laser scanning with stability and robustness. We think it is an important exploration to make a 3D laser scanner consumer-grade and low-cost, making it affordable by the public. Our efforts may help to promote the popularization of 3D laser scanning technology, and make products with 3D laser scanning technology into thousands of households.