GCPs for drone mapping - Emlid

Reach RS+ and RS2

Set up GCPs for
drone mapping

Place ground control points
with RTK receivers.

Starting from $799

Choose a receiver

Placing GCPs with Reach RS+, Lone Drone Services, Canada, Ontario

What GCP is and how it works

Placing Ground Control Points

Reach provides accurate coordinates for GCP
You get repeatable mapping data

Our customer KiteMap from Colombia flew over a site multiple times at different altitudes with DJI Phantom 4 Pro. They processed orthophoto and DEM and extracted contour lines.

Contour lines
without GCPs

Processing software relies only on the drone's GPS data recorded in its photos' EXIF. Therefore, the accuracy of the final orthophoto is only meter-level, so contour lines don't match.

Contour lines
with GCPs

Drone images are georeferenced with GCPs. The final orthophotos are accurate so the contour lines are almost identical and have the same shape.

Drone Pilots using Reach

Drone Pilots using Reach

How Reach receivers work

Reach is an RTK receiver. RTK is a technique used to improve the accuracy of a GPS receiver. Traditional GPS receivers could only determine the position with 2–4 meters accuracy. RTK can give you 1–2 centimeter accuracy.

You don’t necessarily need a second unit for RTK all the time. Usually, there are local services that share base corrections over the Internet. This technology is called NTRIP.

How to get started


Explore the site and place ground control points

Determine all features of the landscape and analyze the amount of GCPs — in most cases, from five to ten points are required.


Connect your rover to a local base or NTRIP provider

Using the ReachView 3 app, create a survey project and choose your local coordinate system.


Collect the coordinates of each GCP with the rover

The Reach receiver allows you to get centimeter-precise data.


Fly a drone

Fly an area to collect aerial images with any drone such as Phantom, Mavic, etc.


Export GCP from Reach in CSV format

Once data is collected, you can export your project in CSV, DXF, GeoJSON, DroneDeploy CSV, or ESRI Shapefiles format.


Import photos and GCP list to mapping software

Upload CSV file with GCPs to your mapping software for accurate georeferencing. Create your project with DroneDeploy, Pix4d, Agisoft, or other mapping software.

Android and iOS

with ReachView 3

Collect points

Create a survey project and collect data in your local coordinate system.

Coordinate systems based on

WGS84, NAD83, GDA2020, and others

Export GCP list to CSV

Record each position as a point with centimeter precise coordinates. You can export your survey project in CSV which is recognized by most mapping software.

Reach is designed for harsh conditions Reach is designed for harsh conditions

Engineered to be tough
Reach receivers are designed to work in challenging conditions, even dusty areas, under the burning sun, and in frosty areas


Working temperature. Isn’t afraid of either heat or cold.


Can be held 1 meter deep underwater for half an hour.

Up to
22 hours

Industrial LiFePO4 battery that doesn’t die of cold. Can charge over USB from a powerbank.

Choosing the set of RTK receivers
Depending on the working area

User reviews

Mapping Iceland Glaciers

Jurijs Ješkins, the researcher at the faculty of Geography and Earth Sciences, University of Latvia

We used two Emlid Reach RS, one as a base and the other as a rover, and were surprised by the good performance and long battery life in very windy, wet, and cold conditions.

Intertidal Oyster Reef Mapping with Reach RS

Anna Windle, Ph.D. Student, Horn Point Laboratory, University of Maryland Center for Environmental Science, USA

The Emlid receiver has proved to be an efficient means of surveying out in the field. A hotspot was used to connect the receiver via Wifi and GPS data was easily collected with a smartphone through the Emlid surveying application page.

Volume Measurement with DJI Phantom 4 and Reach RS+

Isaac Vazquez Flores, Mining Engineer at Dromine, Mexico

Reach RS+ allowed us to quickly collect GCPs before drone mapping with Phantom 4 and helped to carry out precise volume measurements of the feldspar stock. The results obtained with a drone are identical to one obtained with a total station.

in the Emlid Store

The ReachView app and all features of Reach RS2 and Reach RS+ are included

Delivery worldwide.
2-5 days by DHL, up to 3 weeks by airpost.

Find local dealers



  • Dimensions 126x126x142 mm
  • Weight 950 g
  • Operating tº -20…+65 ºC
  • Ingress protection IP67 (water and dust)


  • Autonomy 16 hrs as 3.5G RTK rover,
    22 hrs logging
  • Battery LiFePO4 6400 mAh, 6.4 V
  • External power input 6–40 V
  • Charging USB Type-C 5 V, 2 A
  • Certification FCC, CE


  • Static H: 4 mm + 0.5 ppm
    V: 8 mm + 1 ppm
  • PPK H: 5 mm + 0.5 ppm
    V: 10 mm + 1 ppm
  • RTK H: 7 mm + 1 ppm
    V: 14 mm + 1 ppm
  • Convergence time ~5 s typically


  • LoRa radio
  • Frequency range 868/915 MHz
  • Power 0.1 W
  • Distance Up to 8 km
  • 3.5G modem
  • Regions Global
  • Bands Quad-band, 850/1900,
    900/1800 MHz
  • SIM card Nano-SIM
  • Wi-Fi 802.11b/g/n
  • Bluetooth 4.0/2.1 EDR
  • Ports RS-232, USB Type-C


  • Corrections NTRIP, VRS, RTCM3
  • Position output NMEA, LLH/XYZ
  • Data logging RINEX with events
    with update rate up to 10 Hz
  • Internal storage 16 GB
    160+ days of logging at 1 Hz


  • Signal tracked GPS/QZSS L1C/A, L2C
    BeiDou B1I, B2I
    Galileo E1-B/C, E5b
  • Number of channels 184
  • Update rates 10 Hz GNSS
  • IMU 9DOF


  • Dimensions 145x145x85 mm
  • Weight 690 g
  • Operating tº -20…+65 ºC
  • Ingress protection IP67 (water and dust)


  • Autonomy Up to 30 hrs
  • Battery LiFePO4 3.2 V
  • External power input 6–40 V
  • Charging MicroUSB 5 V
  • Certification FCC, CE


  • Static horizontal 5 mm + 1 ppm
  • Static vertical 10 mm + 2 ppm
  • Kinematic horizontal 7 mm + 1 ppm
  • Kinematic vertical 14 mm + 2 ppm


  • LoRa radio
  • Frequency range 868/915 MHz
  • Distance Up to 8 km
  • Wi-Fi 802.11b/g/n
  • Bluetooth 4.0/2.1 EDR
  • Ports RS-232, MicroUSB


  • Corrections NTRIP, RTCM3
  • Position output NMEA, LLH/XYZ
  • Data logging RINEX with events
    with update rate up to 14 Hz
  • Internal storage 8 GB


  • Signal tracked GPS/QZSS L1, GLONASS G1,
    BeiDou B1, Galileo E1, SBAS
  • Number of channels 72
  • Update rates 14 Hz / 5 Hz
  • IMU 9DOF

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Email us at info@blog.emlid.com or fill in the contact form. Our application engineers reply you within a working day (9:00-18:00 CET).

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