In the realm of phenotyping and agricultural research, image analytics has emerged as a powerful tool for extracting valuable insights. However, beneath the surface lies a crucial element that often goes unnoticed but plays a pivotal role in ensuring accurate analysis and interpretation georeferencing plots. Georeferencing involves assigning geographic coordinates to specific locations within field trials, enabling the reconstruction of Orthomosaic and facilitating precise data processing. In this blog post, we will explore the significance of georeferencing plots and shed light on the importance of coordinate systems, file formats, and advancements in technology for harnessing the full potential of image analytics in phenotyping.


The Earth's Complex Geodetic Shape


Contrary to popular belief, the Earth is not a perfect sphere. It is slightly flattened at the poles and bulged at the equator, resulting in an irregular shape known as the geoid. Recognizing this, coordinate systems have been designed to account for the specific geodetic deformations in different regions, minimizing errors in positioning and representation. By aligning our data with accurate coordinate systems, we can ensure precise georeferencing and eliminate discrepancies that may arise during image analysis.

Geoid representing the Earth


Reconstructing Orthomosaics


Georeferencing plots within field trials allow to reconstruct Orthomosaic, a bird's-eye view of the field. An Orthomosaic comprises an RGB image superimposed with the associated plot map, which delineates the division of plots within the entire field trial. With a well-constructed Orthomosaic, we can accurately process data and deliver results through interactive and visual maps that showcase calculated traits for each individual plot. This approach enhances the clarity and interpretability of the obtained data, enabling data-driven decision-making. To ensure optimal plot patterns reconstruction we generally use Ground Control Points (GCP) that are positioned in the field and help identifying the orientation of the field, the origin of plot X1Y1 and make good alignments during the photogrammetry process.

Simplified process of creconstructing the orthomosaic of a field trial with GCPs.


Choosing the Right Coordinate System


Multiple coordinate systems exist to represent and locate points on the Earth's surface. Two widely used systems are WGS 84 (World Geodetic System 1984) and UTM (Universal Transverse Mercator). WGS 84 is a geodetic coordinate system that provides geographic coordinates—latitude, longitude, and altitude—based on a mathematical model describing the Earth's shape. UTM, on the other hand, is a projected coordinate system that divides the Earth into zones, allowing for more precise measurements within each zone. The choice of coordinate system depends on the specific requirements of the research, but in our experience, UTM coordinate systems have proven to be more efficient and precise as we can see with the example below:

The importance of choosing the right coordinate system: on the left, the length of the plot is 10.79m, while on the right, it is 8.81m.


File Formats and Preserving Geographic Information


In addition to coordinate systems, the file format used for storing GPS coordinates is crucial for preserving geographic information. At Hiphen, we recommend specific formats such as shapefile, GeoJSON, geopackage, and KML. These formats ensure that the geographic information contained in the data is preserved and accessible during analysis. Choosing alternative formats like CSV can lead to the loss of vital information regarding the coordinate system used during data acquisition, hindering proper interpretation and analysis.


Advancements in Data Collection Technology


Thanks to advancements in drone, robotics, and GPS technologies, collecting GPS data has become increasingly automated and efficient. Metadata recorded directly in each image simplifies the process of gathering accurate georeferencing information. By leveraging these technological improvements, researchers can streamline their data collection processes and enhance the accuracy and reliability of plant assessments. This is mostly possible currently thanks to RTK technology. RTK means Real Time Kinematic, and this geolocation technology allows a centimeter-level positioning of the measured object, with real-time synchronization. Such technology is now implemented as standard in most of the latest generation of portable drones with GPS modules mounted on top of the devices, but at Hiphen we also use it as an independent module mounted on a stick, for georeferencing GCPs position, or even mounted on our autonomous PhenoMobile robots.


Field operator collecting GPS coordinates of ground control points with RTK precision device.


Collaborating with Hiphen to Acquire Research-Grade Data


At Hiphen, we understand the importance of research-grade data collection and processing. Our experts work closely with researchers to define the best protocols for ensuring high-quality data collection. We navigate through various projected coordinate systems, adapting to the location of the field, to ensure the measurements of plots align accurately with real-world observations. By partnering with Hiphen, researchers can leverage our expertise in georeferencing plots and unlock the full potential of image analytics for phenotyping.


Georeferencing plots for image analytics is an essential but often overlooked aspect of phenotyping. The process of assigning geographic coordinates to field trial locations enables the reconstruction of Orthomosaic, leading to accurate data processing and visualization. Choosing appropriate coordinate systems, file formats, and harnessing advancements in technology empowers researchers to extract meaningful insights from their data. Collaborating with experts like Hiphen ensures that research-grade data collection and processing are achieved, ultimately advancing agricultural research, and propelling the field of phenotyping to new frontiers.



Your Hiphen Team.
Topic brought to you by Adrien Vielix - Field Acquisition Manager @Hiphen.