{"id":3110,"date":"2023-06-12T12:44:00","date_gmt":"2023-06-12T12:44:00","guid":{"rendered":"https:\/\/oxts.com\/?p=3110"},"modified":"2025-12-22T10:04:44","modified_gmt":"2025-12-22T10:04:44","slug":"what-positioning-technology-is-right-for-your-uav-gcps-gnss-ppk-or-rtk","status":"publish","type":"post","link":"https:\/\/www.oxts.com\/zh\/what-positioning-technology-is-right-for-your-uav-gcps-gnss-ppk-or-rtk\/","title":{"rendered":"\u54ea\u79cd\u5b9a\u4f4d\u6280\u672f\u9002\u5408\u60a8\u7684\u65e0\u4eba\u673a--GCP\u3001GNSS\u3001PPK \u8fd8\u662f RTK\uff1f"},"content":{"rendered":"\n
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If you\u2019re in the market for a survey UAV or drone, you\u2019ll no doubt be knee-deep in technical specs as you try and evaluate different models (or even different components, if you\u2019re building a UAV payload from scratch). But, what positioning technology is right for your UAV?<\/h5>\n\n\n
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One of the things you will be evaluating is, of course, accuracy. Accuracy is important for two reasons. Firstly, you want your UAV to be where it\u2019s supposed to be and secondly, you want to be able to accurately georeference the data you\u2019re gathering with your payload. But (as you will no doubt have already discovered), accuracy isn\u2019t as simple as looking for a number. You\u2019ll have spotted various acronyms accompanying those numbers \u2013 GPS, PPK, RTK, and GCP most commonly, but you may also see GNSS thrown into the mix. In this article, we\u2019ll explain what these acronyms mean \u2013 and what they mean for your UAV project.<\/span>\u00a0<\/span><\/p>\n\n <\/div>\n\n <\/div>\n <\/div>\n \n \n <\/div>\n\n\n

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What are GCPs? <\/h5>\n\n\n
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GCP<\/strong><\/a>\u00a0stands for Ground Control Points, and they are the most inexpensive method of ensuring your data is accurately georeferenced. They are physical targets that you place on the ground, and which you know the GNSS coordinates for. Once your UAV has finished its survey, those points can be used to<\/span>\u00a0reference the position of your UAV in the global frame.<\/p>\n\n <\/div>\n\n <\/div>\n <\/div>\n \n \n <\/div>\n\n\n \n

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The biggest drawback with GCPs is that they don\u2019t help your UAV know its own position. GCPs only help provide your UAV with a general position reference. So GCPs aren\u2019t any use if you want your UAV to fly pre-programmed flight plans. For that, you\u2019ll need a GNSS-based solution like an\u00a0INS<\/strong><\/a><\/span>.<\/p>\n

GCPs can also be time consuming to use and cause additional difficulties at the post-processing stage.<\/p>\n<\/div>\n<\/div>\n<\/div>\n\n <\/div>\n\n <\/div>\n <\/div>\n \n \n <\/div>\n\n\n

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What is GNSS?<\/h5>\n\n\n
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GNSS stands for Global Navigation Satellite System, and refers to any technology that uses satellites
\nto determine its location. GPS is a type of GNSS (and the two are often used interchangeably), but it is
\nnot the only one. There are three others that can be used across the globe (Galileo, BeiDou and GLONASS). Other more regional satellites are also available.<\/span><\/p>\n

Many\u00a0<\/span>UAVs will have a GNSS receiver built in \u2013 it\u2019s what enables them to know where they are on the planet, after all. Using GNSS only, most drones can get accuracy of 3-5 metres. This level of accuracy
\nisn\u2019t too bad for some applications, but definitely not accurate enough if you\u2019re trying to use the position data for mapping activities.<\/span>\u00a0<\/span><\/p>\n\n <\/div>\n\n <\/div>\n <\/div>\n \n \n <\/div>\n\n\n \n

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What is PPK? <\/h5>\n\n\n
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Most drones advertise PPK capabilities \u2013 and it stands for Post-Processed Kinematics. It\u2019s a method of squeezing extra accuracy out of your GNSS signal.\u00a0<\/span>We have a blog here<\/strong><\/a>\u00a0that describes how it works (we talk about RTK, which we also cover below, but the principles are the same).<\/span>\u00a0<\/span><\/p>\n

The main thing to note about PPK is that you can\u2019t use it in real time. Drones with PPK capabilities can provide data that\u2019s centimetre-level accurate in optimum conditions, but that accuracy can\u2019t be used for navigating the drone itself. It also means that for activities that require centimetre-level accuracy in real time, PPK doesn\u2019t deliver.<\/span>\u00a0<\/span><\/p>\n<\/div>\n<\/div>\n\n <\/div>\n\n <\/div>\n <\/div>\n \n \n <\/div>\n\n\n

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What is RTK? <\/h5>\n\n\n
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RTK is the best you can get when it comes to position accuracy. RTK stands for Real-Time Kinematic, and just like PPK it can get you centimetre-level accuracy \u2013 but in real time, rather than in post-processing.<\/span><\/p>\n

For most mobile mapping activities RTK accuracy is the goal, particularly if you\u2019re using a LiDAR sensor to create georeferenced point clouds.<\/span><\/p>\n

Without RTK accuracy for the duration of your LiDAR survey, your pointcloud may be unusable. The additional accuracy RTK offers could be used to tackle more challenging environments \u2013 providing you have the tools to remain with RTK accuracy for as long as possible in the absence of GNSS.
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Most off-the shelf UAVs won\u2019t have RTK capabilities built in, however to get this level of accuracy, it\u2019s likely that you\u2019ll either need to purchase a top-of-the-range UAV, or invest in a custom UAV (either built by you, or by a professional company).<\/span>\u00a0<\/span><\/p>\n\n <\/div>\n\n <\/div>\n <\/div>\n \n \n <\/div>\n\n\n \n

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What\u2019s right for me? <\/h5>\n\n\n
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Generally speaking, if you\u2019re involved in mobile mapping activities then at the very least you will need PPK capabilities. Without those, you won\u2019t be able to georeference your data with enough accuracy to be of use to anyone.<\/span>\u00a0<\/span><\/p>\n

When considering the difference between PPK and RTK, you need to consider:<\/span>\u00a0<\/span><\/p>\n