问答视觉定位和Leica GS18 I
产品工程师METKA MAXERIC回答有关视觉定位技术和Leica GS18 I GNSS RTK Rover的问题。
What are the challenges when surveying with a conventional GNSS sensor?
To be able to measure points, a GNSS sensor needs to receive satellite signals. The position of a point can only be measured when the GNSS RTK sensor hasaccess to the open sky and the pole tip is physically in reach of the point. If this is not possible surveyors can use alternatives methods such as:
- Different workarounds e.g. taping offset, using COGO functionality and sketching
- 其他设备与GNSS RTK传感器结合使用，例如CS20与integratedDISTO or a 4 metre pole. This way of measuring can be time-consuming and may also compromise the accuracy.
- 替代传感器，例如总站。亚博5分钟快三当只有几个点无法用GS传感器测量时，使用此类替代方案也可能是耗时的。
用户面临额外的挑战，当a lot of detail needs surveying. Measuring every single point with the pole tip requires a lot of time on site. There is also a risk that some points are missed, and the site needs to be revisited resulting in additional costs.
Leica GS18我如何克服这些挑战？
With the GS18 I there is no need to use other time-consuming methods or additional equipment. Due to the integration of GNSS, IMU (Inertial Measurement Unit) and a camera, the points with obstructed view to the sky and other inaccessible points can be measured from images using the Visual Positioning technology within GS18 I. This new technology allows points of interest captured from a distance to be measured with survey-grade accuracy.
我n which situations would surveying professionals use Visual Positioning technology?
Visual Positioning is particularly appropriate for:
- 绘制数百点。
- Measuring inaccessible points such as across a busy street, behind a gate or in dangerous areas (e.g. with the risk of being attacked by a dog, hazardous utilities, on a roof edge).
图1 -Leica GS18 I GNSS RTK ROVER，同时测量栅栏上的点
- Surveying points in places with GNSS signal obstruction (e.g. under a roof, balcony or tree).
- 测量建筑物立面上的点（例如，窗户的拐角和屋顶的高度）。
Figure 2 - Measuring faCADES
- Measuring additional points without the need to revisit the site.
- Generating point clouds of captured objects.
图3-由GS18 I捕获的图像组生成的点云
- Volume calculation of stockpiles.
- 捕获碰撞场景的图像以进行点测量。
Figure 4 - Capturing a crash scene
谁应该使用GS18 i？
GS18 I是为需要轻松测量到常规GNSS RTK ROVER挑战的用户而设计的。GS18 I是用户在现场收集大量数据的理想工具。用户可以稍后决定，哪些点可以测量图像调查级准确性。
How does the GS18 I work? (Measurement principle)
Let’s take the following video as an example.
A user wants to measure some points of interest in the trench. All that needs to be done is to walk along the trench with the camera pointed towards the pipeline while the GS18 I automatically captures images. The GS18 I captures images at the rate of 2 Hz ensuring the optimal image overlap and geometry. Once the capturing is stopped, the images will be automatically processed by the algorithms running on Captivate. The images can be used for point measurement right after the captured images are processed.
During capture, GS18 I checks whether the position and tilt quality are sufficiently accurate. If not, the capturing is automatically stopped, but the images that were already captured are processed. In addition, GS18 I establishes a geometric connection between consecutive images by extracting features (distinctive points) from images.
The following video shows how the algorithm running on the GS18 I tracks the features during capture:
The images can be used for point measurement immediately after. This is made possible by the Visual Positioning technology.
Which software is needed to process captured images?
GS18 I is fully supported by Captivate software running on the CS20 LTE or BASIC controller or the CS35 tablet.
Caintivate将自动处理，定位和定向捕获的图像，从而确保现场已经有质量控制。在使用类似技术时，无需手动匹配任何参考点或行。
How can points be measured in images and which software is needed?
Points are measured from images within Captivate running on the CS20 LTE or BASIC controller or the CS35 tablet. Users can measure points in the field right after the images are captured.
图像也可以进口到无穷大，用户可以在大屏幕上测量办公室中的点。
Simply pick one point in an image and the algorithm will automatically match the same point in the other images. With one click the 3D coordinates of the measured point will be calculated and stored within Captivate, just as they would have been with the pole tip.
当使用其他解决方案从图像中计算3D坐标时，必须从每个图像中手动挑选点。使用GS18，我不需要在每个图像中手动选择该点，就像该算法为您完成此工作一样。当采摘点以连续图像匹配时，该点的3D位置通过正向交叉点重建，如下图所示。
图5-前面的交叉点
What is the fundamental principle behind Visual Positioning technology?
Visual Positioning technology is based on the information provided by the GNSS positions, the IMU and the captured images.
Figure 6 - Sensor fusion
让我们以以下视频为例，以测量原则为例。
To measure points with a GS18 I, go to the start position and begin capturing images in Captivate. Now walk along, holding the GS18 I with its camera facing the corner. Images will be automatically captured with a frequency of 2 Hz. After the capturing is stopped, Captivate automatically computes the position and the orientation of the images in a global coordinate system, by integrating the data from the GNSS and the IMU with features recognised in the images. These images are then saved as an image group within Captivate.
图像是实时处理的，可在捕获停止后立即用于测量点。仅使用一个图像，可以单击一次点数。在Captivate上运行的算法将自动匹配其他图像中的选择点，并通过正向交叉点计算局部坐标系中点的坐标。
我s it also possible to create point clouds from captured images?
Yes, images captured with the GS18 I can also be used in Infinity office software to generate 3D point clouds.
How does the GS18 I differ from GS18 T?
GS18 I是Leica Geosystems的GS传感器投资组合的新旗舰产品。它具有GS18 T的所有功能，并具有视觉定位技术的附加值。
Just like any other GS sensor, the GS18 I can use RTK corrections from all GNSS correction services. For optimal measurement performance with the GS18 I, we recommend using HxGN SmartNet, a GNSS correction service, that can be used with any GNSS device, and is constantly monitored for integrity, availability and accuracy.
Why should I invest in the Leica GS18 I?
Here's why the GS18 I can be of benefit for users:
- 我是一个的GS18多才多艺的GNSS RTK传感器。它可以用来衡量点with a levelled or tilted pole. In addition, it can be used to measure inaccessible points withsurvey grade accuracy通过捕获和measuring from images.
- 我naccessible points can be easily captured in images without compromisingsafety。无需担心如何在繁忙的街道上测量要点或与危险狗的物业。
- 通过有效捕获场景并稍后决定，减少现场时间。这会提高生产率，因为您可以测量现场或办公室中图像的点，也无需返回站点即可测量新的点。
What should a user consider when using the GS18 I?
Visual Positioning technology is based on the GNSS and IMU measurements as well as the images captured with the integrated camera. There are some conditions that should be considered, when using the GS18 I for measuring from images:
- GS18 I needs to have sufficient reception of GNSS signals for the duration of the measurement. If tracking of the GNSS satellites is lost, the capture will automatically stop.
- 如果需要视觉定位，请避免在黑暗条件下或直接面对太阳时使用它，因为捕获的图像中的足够特征将不容易识别以匹配它们。
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For optimal accuracy and performance, capture the object of interest from a distance between 2m and 10m.
When the images are captured from the distance lower than 2 m, the images can be blurred due to the fixed focus of the camera.On the other hand, when the images are captured from the distance bigger than 10 m, the accuracy decreases.
我t is possible to capture images from a distance less than 2 m or greater than 10 m from the object. In such cases, the user has to take into consideration, that the accuracy may be reduced. There is also a risk that measuring points using images will not be possible.
- 我mage capture speed is optimised for normal walking speed. It is not possible to use the GS18 I mounted on a moving vehicle because the images might be blurred.
METKA MAXERIC
产品工程师
Leica Geosystems
To learn more about theLeica GS18 I, please visit:www.secondwindkites.com/GS18I
Online Learning
Leica Geosystemshas developed an online learning platform, to further educate customers to use the functionality of their instruments to the maximum.
Leica Geosystemshas developed an online learning platform, to further educate customers to use the functionality of their instruments to the maximum.
