This can be more than you want or want to recognize the complexity of a cell mapping machine (MMS), but here’s an explanation the common Joe can apprehend for the ones involved. When you have a Mobile Mapping System to arrive for your process website to perform a laser test, the gadget seems like little more than an elegant piece of PVC strapped to the top of a four-wheel-drive SUV. Don’t be fooled by way of its simple appearance. Inside is a contemporary miracle… A fashioning together of impartial and amazingly
complicated structures that, when added collectively, produce what would have appeared impossible not so long ago. While fired up, this little white field of marvel begins speaking with as many satellites in the area as it can locate. Positions are installed. Movement and headings are monitored at breathtaking velocity with each reading time-stamped so that every few seconds. At the same time, the computer catches its breath, and the unbiased portions of information are perfectly spliced and returned together with complex corrections to expose an elegant reproduction of the surface that became pushed past. It is a factor of beauty.
Tech-savvy MMS vendors use this amalgamation of technology to provide their customers with cellular laser scanning offerings that produce an X, Y, and Z factor cloud in State Plane or comparable coordinate structures. Here is an outline of the various technologies used and how they tie collectively to generate an accurate three-D description of the regions surveyed:
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How To Determine Position – GPS
Mobile Mapping Systems (MMS) use the Global Positioning System (GPS) to determine where we are at a given time. The accuracy of the raw GPS data isn’t adequate for our purposes, so we certainly use one of three technologies to accurately the basic position facts. If we have a recognized control factor near the job, we
can set up a GPS base station over that factor and use measurements of GPS role from the satellites to determine the difference among the measured and actual function of that point every 2d. These blunders or “differential” are transmitted via radio link to the Mobile Scanner, and the GPS facts accumulated through the Scanner every 2nd are corrected. This technique is known as Real-Time Kinematic or RTK. If no management factor is available, we can establish one and, using enterprise-preferred tools, decide its location later. Using RTK, we can set up our function within ±1 inches in Easting and Northing and ±2 inches in elevation.
We use the second method to decide our position, which is much like RTK but is named Virtual Reference Station or VRS. In this approach, we enroll in a provider with some base stations (the VRS Network) installation in a given region. We use Wi-Fi data hyperlinks to get the GPS corrections from this Network, and the facts from the GPS on the Mobile Scanner are corrected as in the RTK method.
The accuracy of this system is corresponding to RTK. The 0.33 technique we use to decide position makes use of OmniStar®, a personal satellite-based correction provider. It gives corrections in a manner just like VRS, except that we use a satellite receiver to get hold of the facts in place of a wireless link. The accuracy of OmniStar® is slightly much less than RTK or VRS at ± four inches. We can mix and match this technology as essential – as an example, we will use RTK to do the scan; however, define the control point using the OmniStar® gadget to cast off the need for figuring out the manage point position later.
How To Measure Changes in Direction – Inertial Measurement Unit
Using GPS technology, we degree our position appropriately about once consistent with 2D. However, we’re continuously converting courses. At five miles per hour, we journey about seven toes compatible with a second. During that 2d, we may additionally change our course of travel (heading) through many tiers.
The inertial measurement unit (IMU) measures modifications in the Scanner heading one hundred instances consistent with 2D. The accuracy of the IMU is ± zero.One stage (~ zero.17 toes at a distance of 100 toes away). The function of the Mobile Scanner is robotically reset when it gets a new GPS role “restoration” every 2d, so any small blunders from the IMU are not allowed to accumulate.
How To Collect Data of the Topography – The Laser Module
Using GPS technology and an IMU, we can maintain the song of the Mobile Scanner’s exact position at each factor in time. The GPS and IMU are both established within the scanner housing. Outside the accommodation, we have a rotating laser module. This Scanner has a distance-measuring laser mounted at the right perspective to the path of a tour of the automobile or vessel. The laser measures 36,000 factors a 2nd, rotates up to 10 RPM, and has as many as 450 feet.
The accuracy of the space dimension is ~± 2 inches. The distance among factors is controlled using the laser RPM and the automobile’s velocity. We commonly generate a point cloud with points ~ zero, 5 to two feet apart. The statistics can be thinned to lessen the size of the information sets if preferred. If better records insurance is required, the settings within the manipulate software program can be changed. The Mobile Scanner can scan something it’s far driven past above, under, or to both facets of the Scanner.
How To Correct for Uneven Ground – Pitch and Roll Sensors
The Mobile Scanner is mounted to a car or vessel. In a perfect international, the ground or frame of water would be perfectly horizontal. Since this is glaringly no longer the case, we accurate the records with the aid of measuring the pitch (uphill or downhill attitude) and roll (left or proper angle) of the Scanner using pitch and roll sensors. These gadgets degree pitch and roll 100 times per 2d to an accuracy of ± 0.01 tiers (~ 0.02 toes at a distance of 100 toes). Because these instruments measure the Mobile Scanner attitude so frequently, we can travel over rough terrain or in rough seas at affordable speeds without severely impacting the accuracy of the facts.
Summary
Mobile LiDAR or Mobile Scanning is sometimes referred to as can provide formerly remarkable performance and accuracy in lots of survey programs. Whether you need to degree the number of your stockpiles, do special mine-making plans, degree seashore erosion, determine flower encroachment on the application right of way, or solve many survey or engineering problems, Mobile LiDar can also solve your issues.
