Set up ground
control points
for drone mapping

Place ground control points
with RTK receivers.


Choose a receiver

Placing GCPs with Reach RS2 for DJI Mavic 4 RTK surveys, Thorsten Kahlert, Iceland

What GCP is and how it works

Placing Ground Control Points

Reach provides precise 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

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 for your drone survey — in most cases, from five to ten points are required.


Connect your rover to a local base or NTRIP provider

Using the Emlid Flow 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 the 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 Emlid Studio

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

Survey with Emlid Flow
and manage data with Emlid Flow 360

Emlid Flow is a mobile app for iOS and Android. It handles all the fieldwork—receiver settings, data collection, and stakeout. All survey data is in sync with a cloud-based service Emlid Flow 360. It allows you to access your projects from the browser and manage survey data.


Collect points and write detailed descriptions in a few taps. To create a project for data collection, enter your coordinate system manually or choose one from the library. The app supports thousands of coordinate systems, projections, grids, and geoids.

Coordinate systems based on

WGS84, NAD83,
GDA2020, and others

Log raw data

Point collection and recording of raw data are independent processes and can be used simultaneously. RINEX logs are compatible with OPUS, AUSPOS, and PPP services, so you can get cm-precise results anywhere on Earth.

For post-processing, you can use our free PPK software Emlid Studio.

Work with different background maps

Upload topographic maps, cadastral plans, and aerial imagery from WMS and WMTS sources or work with a built-in satellite map.

Managing projects in the cloud

The Emlid Flow app is synchronized with the Emlid Flow 360 service. This allows you to create and access survey projects, manage coordinate systems, and export and import data using both the mobile app and the cloud service at

Export and import formats

CSV, DXF, and Shapefile

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

-20 to
+65 ºС

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.

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 basic features of Emlid Flow are available for free to all Emlid users.

Shipping from Chicago

2-3 days by USPS Priority Mail Express
2-7 days by FedEx, UPS

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Reach RS2+ Datasheet
135 kb


  • Dimensions 126 x 126 x 142 mm
  • Weight 950 g
  • Operating tº -20 to +65 ºC
  • Ingress protection IP67


  • Autonomy 16 hrs as LTE RTK rover,
    22 hrs logging
  • Battery LiFePO4 6400 mAh, 6.4 V
  • External power input 6–40 V
  • Charging USB Type-C 5 V, 3 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
    0.1 W
    Up to 8 km
  • LTE modem Regions
    FDD-LTE: 1,2,3,4,5,7,
    8, 12, 13, 18, 19, 20,
    26, 28, 66
    TD-LTE: 38,40,41
    1,3,2,4,5,6, 8,19
    Quad-band, 850/1900,
    900/1800 MHz
    SIM card Nano-SIM
  • LTE modem Regions
    FDD-LTE: 1,2,3,4,5,7,
    8, 12, 13, 18, 19, 20,
    26, 28, 66
    TD-LTE: 38,40,41
    1,3,2,4,5,6, 8,19
    Quad-band, 850/1900,
    900/1800 MHz
    SIM card Nano-SIM
  • Wi-Fi 802.11 b/g/n
  • Bluetooth 4.0/2.1 EDR
  • Ports RS-232, USB Type-C


  • Corrections NTRIP, RTCM3
  • Position output NMEA, LLH/XYZ
  • Data logging RINEX
  • Internal storage 16 GB
    160+ days of logging at 1 Hz


  • Signal tracked GPS/QZSS L1C/A, L2C
    BeiDou B1I, B2I
    Galileo E1B/C, E5b
  • Number of channels 184
  • Update rates up to 10 Hz

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(9:00-18:00 CET).

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