Hi, my company is planning to buy DJI Phantom 4 RTK for land surveying of construction sites, which are in hilly terrain.  Is the drone suitable when the ground is hilly?
In addition to buying the drone and its standard accessories that comes with the package, do we need to buy other accessories, such as ND filters, smart contollers etc.?
Final question: is this model going to be replaced by a newer model (say Phantom 5 RTK) soon?

1) yes, works great with hilly terrain.
2) no need of accessories
3) i think nobody knows that, i supposed there will be a phantom 5, and maybe a p5rtk. For more capabilities you can buy matrice 300 rtk ... but $$$$$

Guille_Meinero Posted at 1-19 04:48
1) yes, works great with hilly terrain.
2) no need of accessories
3) i think nobody knows that, i supposed there will be a phantom 5, and maybe a p5rtk. For more capabilities you can buy matrice 300 rtk ... but $$$$$

Thank you very much.  
By the way, is the built-in screen of the remote controller bright enough in sunny days or do we need to replace it with CrystalSky?
Budget is not a big concern as the cost is only a very tiny proportion of the construction contract sum.  Is Matrix 300 RTK able to achieve higher precision in aerial photogrammetry than Phantom 4 RTK?  The site has a lot of excavation works and we intend to use the drone for monthly topographical surveys to compute the earthwork volume between consecutive surveys.  Can the horizontal/vertical precision be sub-centimeter?

the built-in screen could be brighter, but i can work without problem.
M300 rtk has a lot of new features, but no, you will not get sub-centimeter precision with photogrametry. Maybe you need Lidar, M300RTK has lidar capabilities.

Guille_Meinero Posted at 1-19 04:48
1) yes, works great with hilly terrain.
2) no need of accessories
3) i think nobody knows that, i supposed there will be a phantom 5, and maybe a p5rtk. For more capabilities you can buy matrice 300 rtk ... but $$$$$

I don't know if I would say it works "great" in hilly terrain. In my opinion its kind of a pain having to deal with custom DEMs where other platforms download the dem on the fly when planning the flight. Also, having to worry about barometer altitudes, ellipsoid dem etc. adds to pain.

Just my humble opinion.

CCAM Posted at 1-20 14:31
I don't know if I would say it works "great" in hilly terrain. In my opinion its kind of a pain having to deal with custom DEMs where other platforms download the dem on the fly when planning the flight. Also, having to worry about barometer altitudes, ellipsoid dem etc. adds to pain.

Just my humble opinion.

Thank you.  It is also my concern as I understand that the drone has to fly close to the ground in order to increase the precision of aerial photogrammetry.  For topographical survey of hilly terrain, does it mean that the drone has to fly up and down roughly following the ground profile?  Is Phantom 4 RTK or Matrice 300 RTK able to automatically fly at constant height above the ground profile?

CCAM Posted at 1-20 14:31
I don't know if I would say it works "great" in hilly terrain. In my opinion its kind of a pain having to deal with custom DEMs where other platforms download the dem on the fly when planning the flight. Also, having to worry about barometer altitudes, ellipsoid dem etc. adds to pain.

Just my humble opinion.

Custom dem is downloading and copying.... ok , not on the flying but is really easy

SYC Posted at 1-20 18:24
Thank you.  It is also my concern as I understand that the drone has to fly close to the ground in order to increase the precision of aerial photogrammetry.  For topographical survey of hilly terrain, does it mean that the drone has to fly up and down roughly following the ground profile?  Is Phantom 4 RTK or Matrice 300 RTK able to automatically fly at constant height above the ground profile?

The constant height above the ground depends on quality or resolution of the dem uploaded. You can use you own dem.
I insist, if you need detailed DTM, maybe you need lidar. Faster to get data, almost no postprocess (instead of photogrammetry which usually is a lot of time) and more accuracy.

You'll never get sub-centimeter accuracy with today's airborne platforms. Even when using an onsite base station, PPK GEOTAGs and ground control points, you might see 2-4 cm vertical accuracy. To achieve this you'll need to calibrate the focal length.
Sub-centimeter accuracy is a challenge for terrestrial based scanning.

I agree the CCAM,  terrain following with the P4RTK is tedious and error prone. Once you figure out the workflow, it's not too bad but way more painful than it should be.

I've been tracking lidar progress for several years. Most advertise 2-4 cm vertical accuracy.   I think RIEGL is offering something with 10mm accuracy, but last I looked it was an order of magnitude more expensive than the m300.

Let us know what you decide.,

I'm with CCAM and Skyveyor112 on this one. P4 RTK can achieve a couple cm Z precision with some work. It's a good platform for the price. Terrain following, like other aspects of the software, is half-baked. It works but not like you wish it did.

About a month ago, my colleague used P4 RTK and DJI Terra for aerial photogrammetry and produced 3D terrain model which is fairly accurate in coordinates (deviation of maximum 61mm from traditional survey) and elevation (maximum deviation of 183mm from traditional survey) for a hilly terrain.  The terrain model obtained by a first flight plan with constant elevation was uploaded to the remote controller, which then generated a flight plan which was at constant height above the hilly terrain for the second flight to produce a more accurate terrain model.  The whole process was not tedious.
I would be interested to know the order of accuracy achievable by M300 RTK with the latest P1 camera, which is tailored for land surveying.