Nov 29-30, Topodrone team took part at Drones in Finish Agricultural & Forestry congress Naantali, Finland


At the company’s booth, a wide range of upgraded DJI drones for precise survey and agricultural tasks were presented, as well as EMLID GNSS equipment, distributed by Topodrone.


During flight show we made UAV survey over test area. Flights were carried out by DJI PHANTOM 4PRO PPK and DJI MATRICE 200 PPK in the difficult weather conditions with a gusting wind speed up to 15 m/sec.

Fig.3. Mission planning

The entire process of photogrammetry data processing, 3D model generating was performed together with  conference participants.

Fig.4. Data processing

Fig.5. Data processing

4 – 5 cm x,y,z accuracy of 3D model was achieved thanks to the developed by Topodrone algorithm of GNSS & IMU data postprocessing. No ground points were used for aerial data photo triangulation. For accuracy estimating checkpoints with well-known coordinates were used.

Fig.6. 3D model

Fig.7. 3D model

Fig.8. 3D model

Fig.9. 3D model

The great interest of participants  was aroused by presentation of Natural Resources Institute of Finland (LUKE) about the experience of using DJI drones with additionally installed multispectral camera and a high-precision geodetic GNSS receiver for forests monitoring and scaling.

Revolutionary Aerial survey solution with DJI Phantom 4PRO PPK provides up to 2 cm accuracy in India

Topodrone Russia and Matrix Geo Solution India are delighted to introduce the result of composite study done by Institute of Photogrammetry & Geo-Informatics (IPGI), Matrix Geo solutions along with Topodrone Russia concludes, that the upgraded DJI PHANTOM 4PRO PPK drone not only achieves an accuracy of 3-5cm RMSE consistently, but also has potential to achieve an accuracy up to 2cm RMSE, without the need of Ground Control Points.

DJI Phantom + RTK/PPK based Drone, delivers reliable ground accuracy that may be considered as a true alternative to ground control points.

Please read the following case study for more details.

STEP-1. Select Test Area

A test area has been selected, outside of No Flying zone of airports (pic.1). The area was about 110 000 sq. m. (11 hectares), covered by only one battery for every flight altitude ranging from 60/100/150 meters.

Pic.1 Area of interest

STEP-2. Set up of Check Points & Base Station

The base station REACH RS+ GNSS receiver has been installed on the point with known coordinates.

The Check Points have been placed and measured in RTK mode by second REACH RS+ (Rover) in evenly distributed manner throughout the test area to establish the check control points.

Pic.2 Base station

Pic.3 Measuring coordinates of checkpoints

Pic 4. Checkpoints location

STEP – 3 Flight Mission & Aerial Image Acquisition 

Three missions were planned at 60, 100, 150 meters’ altitude with 85% along and 70 % across overlapping, flights were performed with up to 9 m/s speed.

Pic.5 Flight planning

STEP – 4  Data Processing

After all the flights, set of raw images and raw GNSS data were downloaded from the drone and the base station.

The data was converted into Rinex format and post processed by RTKLIB application and as a result precise coordinates of images exposure were received that were further embedded to photos by TOPOSETTER application.

Datasets from different flight altitudes, i.e. 60, 100, 150 respectively were photogrammetrically processed by Photoscan software without using any Ground Control Points.

After processing, the checkpoints coordinates were imported into the Photoscan project and checked for the accuracy of each flight.

The data has also been checked into Traditional Stereo Photogrammetry workstation and the result was found well within 3-4 CM accuracy.

In all the Missions, the results were well within 3-4 CM Accuracy.

Tables for the result against the GCP’s

Table 1. Height 60m

Table 2. Height 100m

Table 3. Height 150m

Conclusion The above results from flights of different altitudes, show that the accuracies achieved are well within two pixel of GSD and hence passes the criteria of the National Standard for Spatial Data Accuracy (NSSDA).

DJI MAVIC PRO PPK — compact and professional solution for geodetic aerial photography without ground control points (GCP)

Good day to all! I want to share the results of practical application of upgraded drones by Topodrone team for high-precision UAV survey, cadastral and geological work, highly detailed 3D modeling.

For the first time modified DJI PHANTOM 4PRO RTK PPK took off to the sky in February 2018, from that moment already more than 30  survey teams all over the world use our drones in work, the geography of their flights is quite wide: Russia, Canada, Finland, Greece, Spain and even Samoa)).

The first flight in February 2018, we carried out at an altitude of 200 meters and achieved an accuracy of 13 to 20 cm without the use of ground control points (GCP). After adjusting the hardware and software, we precisely capture camera events and substantially improved accuracy, now the DJI PHANTOM 4PRO RTK PPK allows to obtain an accuracy of up to 3 cm from a height of 60 m, 5-7 cm from a height of 120-150 m and of the order of 10 — 12 cm from a height of 200 meters. As it seems to us, this is a very good result, which makes it possible to use low cost copter to solve many types of UAV survey.

We do not stop in developing and today we want to represent the most affordable  drone- DJI MAVIC PRO PPK with an additional geodetic GNSS receiver integrated with the camera 12 mp, which allows you to save the coordinates of the images with centimeter level accuracy and create high-precision and detailed three-dimensional terrain models and orthophotos. After tested flights and field works , we confidently confirm that at 80 meters altitude our solution provides the accuracy of of 6-8 cm without using GCP !!!

For testing, we selected an area with well recognized ground control points for further accuracy estimating measured by survey grade GNSS receiver . Flights at a height of 80 meters were performed with double grid routs.

Photos locations

Pic. 1 Photos locations

GCP locations

Pic. 2 GCP locations

After phogrammetric processing with using only accurate images locations captured by Reach M+ and postprocessed by RTK LIB we imported ground control points (Fig. 2) and determined their location on the images, in Table 1 you can see the accuracy report.


X/Longitude Y/Latitude Z/Altitude X_error Y_error


GCP 1 37.454803 55.663711 191.251 -0.05813 0.063793



37.454798 55.663675 191.275 -0.082014 0.044153



37.45459 55.663724 191.299 -0.041473 0.081557



37.454473 55.662803 190.81 0.014146 0.047028



37.454498 55.662802 190.821 -0.034705 -0.000917



37.45513 55.662734 190.678 0.021256 0.020252



37.455183 55.662981 190.807 -0.005663 0.078512



37.455433 55.663009 190.459 -0.003536 0.065889


After building a dense points cloud, orthophotomocaic and a three-dimensional terrain model were created, it is possible to determine the coordinates of any object, as well as to perform the necessary calculations, for example, volume calculation.

3D model of terrain

Pic.3. 3D model of terrain

Pic.4. 3D model of terrain

Key futures and major advantages of DJI MAVIC PRO PPK by Topodrone :

  • impressively portable , when folded down, measuring only 83 x 83 x 198mm – more than compact enough to slip into a small bag;
  • long-range remote control up to 7 km;
  • battery delivering around 27 minutes of flight per charge;
  • Advanced obstacle detection system. Mavic Pro can automatically rise in front of inclined objects such as mountain slopes. In total, there are des 2 sonars and 5 simultaneously working cameras;
  • Survey grade GNSS GPS/QZSS L1, GLONASS G1, BeiDou B1, Galileo E1, SBAS receiver integrated with 12 MP camera allows to capture photos events with centimeter level accuracy and automatically process data in any photogrammetric software;
  • low cost and ease to use extends the possibilities of its application in various sectors of UAV survey.

DJI MAVIC PRO upgraded by Topodrone, having all the above advantages and technological innovations, creates a new trend in the direction of unmanned aerial vehicles for geodesy, and makes them essentially an indispensable tool that every surveyor, mine surveyor, cadastre engineer, archaeologist or geologist will carry with him soon.


Precision agriculture is a farming management concept based on observing, measuring and responding to inter and intra-field variability in crops. The goal of precision agriculture research is to define a decision support system (DSS) for whole farm management with the goal of optimizing returns on inputs while preserving resources.

Topodrone team has developed a set of equipment for precise agriculture on the basis of DJI Phantom 4PRO which are relatively inexpensive and can be operated by novice pilots. These agricultural drone is equipped with survey grade GNSS receiver, PARROT SEQUOIA multi-spectral camera and 20 Mp DJI RGB camera to capture many images of a field that can be processed using photogrammetric methods to create orthophotos and NDVI maps.

It allows to carry in multispectral surveying and obtain the coordinates of the phots position with centimeter accuracy. Now you can process data in Photoscan or Pix4D, etc. software and turn your images into highly precise, georeferenced multispectral 2D NDVI maps and 3D models without ground control points (GCP).

We designed foldable mount for Parrot Sequoia camera. The camera can be easily installed on the drone and powered. You don’t need to use additional power bank, etc.

Mission planning and aerial survey by DJI PHANTOM 4PRO RTK/PPK MULTISPECTRAL and  further photogrammetric processing of multispectral images are similar with technology of geodetic aerial survey which was described in many details in our BLOG .

Step1. Setup a base station on a point with known coordinates.

Step2. Create Flight mission in any applications available (for example, Pix4D, MapPilot, DJI GS Pro, etc.).

Step.3 After the flight, download GNSS raw data from a drone and base, copy photos from DJI and Sequoia cameras.

In the next step, post-processing of GNSS measurements to be performed to determine the high-precision image location, then use Toposetter app to embed accurate coordinates to photos and import them to photogrammetric processing software where automated photogrammetric processing is performed using the exact position of the images. As a result you receive a set of 3D model and multispectral 2D orthomaps with a accuracy of 3 — 7 cm depending of the flight altitude.

Photogrammetry processing

Photogrammetry processing

Digital elevation model

Digital elevation model

Ortomosaic (RGB)

Ortomosaic (RGB)

Ortomosaic (multispectral)

Ortomosaic (Multispectral)

Ortomosaic (RGB+Multispectral)

Ortomosaic (RGB+Multispectral)

Ortomosaic (RGB)

Ortomosaic (RGB)

Ortomosaic (RGB+Multispectral)

Ortomosaic (Multispectral)

UAV Multispectral images classification

UAV Multispectral images classification

Pilot project carried out by Topodrone team of multispectral aerial forest survey in the province of Pohjois-Karjala Finland, showed the possibility of creating a high-precision image mosaic in the multispectral and visible ranges.

For data processing no additional work was required to lay ground control points, which made it possible to simplify the process of field work in the forest area and significantly shortened the project implementation time.

The joint processing of the obtained data allowed a remote method to determine the species, location and height of trees, as well as to find diseased and drying plants.


DJI PHANTOM 4PRO PPK + SEQUOIA camera is a low cost, easy to use tool for precision agriculture such as:

-monitoring of forest areas,

— determination of qualitative and quantitative characteristics of forest areas,

— control of logging;

— real time monitoring of crops condition;

— determination of the vegetative index.


Toposetter is easy to use software for images geotagging and replacing navigation position from images EXIF tags by accurate coordinates after GNSS post processing. Works perfectly with photos captured by any DJI drones and RTK LIB postprocessing software

The following futures were added:

  1. JPG, TIFF, DNG format support
  2. Setting up x,y,z, camera offset
  3. Adjustment of antenna position for antenna tilt

User’s manual:

  1. Select folder with images



2. Select event.pos file



3. Select an appropriate photo and record in event.pos file


4.Click Step 3

5. Set tolerance 1sec


5. Application will create a list of photos with precise coordinates. Q=1 everything OK , q=5 no solution
6. Update EXIF metadata and/or Save list of coordinates in .txt file.

Topodrone for constructions

Topodrone offers wide range of mapping & survey services in the field of design and construction.

With our advanced drone technology we can survey large areas of land more accurately and faster than conventional survey techniques, providing our clients with 3D models, contours and digital elevation models with rapid turnaround.


At the first stage, we establish a network of geodetic benchmarks. This marks made on a monument having a known location and elevation determined by GNSS measurements, serving as a reference point for surveying.

At the second stage we carry out aerial photo or Lidar survey of the territory using unmanned aerial vehicles (UAV) as well as instrumental topographic survey of underground communications.



Our UAVs equipped with an integrated high-precision GNSS receiver or Lidar make it possible to automatically obtain 3D model of the territory with centimeter level accuracy and can provide you with much-needed details regarding the landscape and surrounding areas. This cuts down on equipment and manpower costs, and it offers contractors the ability to make well-informed estimates and decisions prior to accepting contracts or breaking ground.




A large site, such as 40 hectares, can take 2 people 1 week using traditional survey methods. This can be risky due to the need to climb all over the site. With our advanced Drones technology we can map the same area and capture the site in digital format in 3 hours: 1 hour to plan and fly, 1 hour to process, and 1 hour to review data with the customer.

As a result, we provide clients with

  • Benchmarks with known coordinates, installed on the site which can be used for further construction.
  • Accurate and detailed 3D models of the territory
  • Digital elevation models
  • Up to date topographical maps or GIS layers in scale 1: 500 – 1: 5000


During construction, our drones will fly every day to monitor the work in progress.

The processing results of aerial photography and video shooting from the drone can be compared with the finished design and each day, the exact amount of work completed is known.

When construction is finished, the actual work can be compared with the design, to make sure completion is exact. Also, we can create full documentation (2D map, 3D model) for keeping a record of the “as-built”. This is given to the owner and the government in most cases.



Pic.3 3D MODEL


Digital terrain model (DTM)

Pic.4 Digital terrain model (DTM)



Pic.5 Orthophoto


Topographical Map in scale 1: 500

Pic.6 Topographical Map in scale 1: 500


In this article, we would like to continue our publications on the possibility of using the DJI PHANTOM 4 PRO additionally upgraded with accurate GNSS receiver for surveying and mapping, as an example of a practical project for aerial survey of a quarry near Tortosa city in Spain.

I would like to note at once that all the processes of aerial photography and data processing were carried out jointly with local representative responsible for surveying and volume calculating for this quarry.

It didn’t take a lot of time to prepare our drone to work after transportation. It was enough to get a quadrocopter from the transport case, install a removable GNSS antenna and turn on the power of the drone (Fig. 1). Installed on the point with known coordinates Topcon GR3 GNSS receiver was used as a base station.


The flight mission was planned at an altitude of 120 meters from the bottom of the quarry with 80% overlap of images. The total area of the survey was 2 hectares. The relief of the quarry is cut enough, administrative buildings and equipment are placed on the territory. On the slopes and peaks of the mountains  there are a lot of trees and  shrubs (Pic. 2).



The whole process of aerial photography took about 15 minutes.

Preliminary processing was carried out on the-site using a field notebook. We carried out Post-processing of GNSS measurements and photogrammetric processing with using the coordinates of the centers of images determined with a centimeter accuracy by the on-board GNSS receiver (Pic. 3). As a result points cloud (Pic. 4, 5,6) orthomosaic (Pic. 9 ). and DTM were created (Pic.8)









To assess the quality of data we used ground control points provided by the customer. The  errors in plan and height were up to 8 cm and 15 cm, respectively. After focal distance calibrating with using at least one of the reference points, the accuracy in height was improved up to 8 cm.

Finally digital terrain model was created by automatic classification of the points cloud (Pic 7,8)

It should be noted that the resulting 3D model with 5 cm resolution corresponds to LIDAR data, and it is possible to classify vegetation, buildings, structures and other technological objects and create a detailed and accurate 3D terrain model.

The results of this projects fully meet  the requirements of the customer and showed, on a practical example, the following advantages of unmanned aerial survey technology before using traditional methods:

— high accuracy and details

— high efficiency and productivity

— high percentage of automation of the processing

— low cost

— short terms of project implementation

Pic.7 DSM


Pic.8 DTM


Pic. 9 Orthomosaic and contour lines



In the first stage we installed GNSS base station on the point with known coordinates and measured locations in RTK mode of six ground control points distributed over the survey area. (Pic. 1, Pic 2).


Pic.1 Topcon GR 5 GNSS base station


Ground control point

Pic.2 Ground control point


In the second stage a drone mission was planned (Pic.3) , uploaded to DJI PHANTOM 4PRO GNSS RTK/PPK (Pic. 4). The flight mission was performed with the following parameters:

  • survey area 40 hectares
  • flight speed 10 m/s
  • overlap 80/80%
  • altitude 200 meters above ground level.
Location of the survey area and flight routs

Pic. 3 Location of the survey area and flight routs




Stage 3. Photogrammetric processing. After landing, GNSS data were download from the drone via wi-fi and RINEX files from drone and base station were processing together using RTKLib postprocessing software (Pic. 5.). Differences between images locations measured by standard DJI GPS and upgraded GNSS system are shown at Pic.6

центры фотографирования



latitude(deg) longitude(deg) height(m) Q ns sdn(m) sde(m) sdu(m) sdne(m) sdeu(m)



55.42721116 37.09866392 383.2712 1 13 0.0077 0.0049 0.0148 -0.0034 -0.0043



55.42692354 37.09902841 382.1284 1 13 0.0077 0.0049 0.0148 -0.0034 -0.0043



55.42663183 37.09938321 380.809 1 13 0.0077 0.0049 0.0148 -0.0034 -0.0043



55.42634191 37.09974165 379.716 1 13 0.0077 0.0049 0.0148 -0.0034 -0.0043



55.42604749 37.10009267 378.2999 1 13 0.0077 0.0049 0.0148 -0.0034 -0.0043



55.42575137 37.10045163 376.7581 1 13 0.0077 0.0049 0.0148 -0.0034 -0.0043



55.42546214 37.10080242 375.5348 1 13 0.0077 0.0049 0.0148 -0.0034 -0.0043



55.42516381 37.10116678 374.3488 1 13 0.0077 0.0049 0.0148 -0.0034 -0.0043


Pic.5 GNSS post processing report


Photogrammetric processing  was carried out in Photoscan software. Precise coordinates of image position were imported to the project and used for images alignment. Coordinates of ground control points were necessary only for the model accuracy estimation.

The following results were achieved with using precalibrated parameters of focal length F=3642.97108 and GPS offset Z=-0.21. (Pic.7,8,9)

Pic. 7


Accuracy of image locations

Pic. 8 Accuracy of image locations



Pic. 8 Accuracy of GCP location



X/Longitude Y/Latitude Z/Altitude X_error Y_error Z_error


37.108468 55.428252 177.5342 0.095565 0.116266 -0.155084


37.105661 55.429969 185.2419 0.060218 0.108619 -0.057785


37.104604 55.42775 187.5888 0.053902 0.033637


gcp4 37.101668 55.430107 192.0927 0.025702 0.060954


gcp5 37.101818 55.425095 191.8068 -0.048562 -0.088709


gcp7 37.098997 55.427386 192.1309 -0.051945 0.01491


The results of the project shows capabilities to use a low cost DJI PHANTOM 4PRO upgraded with GNSS RTK/PPK receiver as a survey grade UAV. DJI PHANTOM 4PRO RTK/PPK provides high accurate drone data for precise mapping and 3D modelling. You no longer have to lay down GCPs or just minimize their number, saving countless hours and labor costs.

Demo dataset of this project including RAW GNSS files, images and GCP coordinates is available from






  1. Integrated survey grade 444 channel L1, L2 (GPS, GLONASS, Galileo, SBAS) GNSS RTK receiver
  2. L1, L2 GNSS antenna
  3. Built in GSM modem (optional radio modem )
  4. Professionally calibrated X4S 20MP camera
  5. Obstacle avoidance
  6. Working temperature range -20 °C ~ 45 °C
  7. Carrying case
  8. Flight time up to 35 minutes
  9. 1 year Warranty

DJI MATRICE 200 GNSS RTK – professional solution for UAV mapping ad survey:

444 channel L1, L2 (GPS, GLONASS, Galileo, SBAS) GNSS RTK receiver integrated with a professionally calibrated 20MP camera which allows to record photos locations with centimeter level accuracy.

Now you can process data in Photoscan or Pix4D, etc. software and turn your images into highly precise, georeferenced 2D maps and 3D models without ground control points (GCP).

With Built in GSM modem you can work with a network of reference stations in Real Time Kinematic (RTK) mode and you don’t need to use GNSS receiver as a base station.

Dual-battery power system automatically heats batteries when flying in sub-zero temperatures, while an enclosed design ensures weather and water resistance, so you can fly in a wide range of environments.




  1. Ready to fly DJI Phantom 4 PRO
  2. Integrated survey grade GNSS receiver (GPS/QZSS L1, GLONASS G1, BeiDou B1, Galileo E1, SBAS)
  3. Removable GNSS antenna mount
  4. Ready to install Parrot Sequoia camera
  5. Software for GNSS data post processing
  6. Support for operations, PPK data processing and photogrammetry processing.


We would like to announce a low cost survey grade system DJI PHANTOM 4PRO GNSS RTK/PPK MULTISPECTRAL.

Survey grade GNSS GPS/QZSS L1, GLONASS G1, BeiDou B1, Galileo E1, SBAS receiver built in standard DJI Phantom 4PRO body and integrated with professional 20 MP camera. It allows to record photos locations with centimeter level accuracy.

Additionally we designed foldable mount for Parrot Sequoia camera. The camera can be easily installed on the drone and powered. You don’t need to use additional power bank, etc.

During a flight multispectral camera works at the same time as DJI Phantom camera.

Now you can process multispectral data together with high resolution images in Photoscan or Pix4D, etc. software and turn your images into highly precise, georeferenced 2D multispectral maps without ground control points (GCP) for different types of agricultural applications.

You no longer have to lay down GCPs or just minimize their number, saving countless hours and labor costs.

DJI PHANTOM 4PRO GNSS RTK/PPK is a easy to use survey tool. Just prepare flight mission in UGCS, etc software, switch on the drone, perform a flight mission. GNSS receiver will store events of making photo automatically, after landing download data from a drone via WI-FI.

For more detail please read articles about our experience of using DJI PHANTOM 4PRO GNSS RTK/PPK  for topographical survey or visit our BLOG