Technology

The Helimap System® technology is based on heliborne lasergrammetry (LiDAR) and digital photogrammetry. The use of airborne vectors allows us to reach even the most inaccessible project sites.

Sixense Helimap uses its own equipment, designed in-house and protected under the name Helimap System®. This technology is the fruit of a joint research carried out in the laboratories of photogrammetry and topometry of the Swiss Federal Institute of Technology Lausanne (EPFL).
Helimap System® is based on the combination of a laser scanner, a high-resolution digital camera and a very high quality direct georeferencing navigation system (GPS-IMU).

More than 15 years of experience

Active since 2003 as a LiDAR pioneer, and since 2008 as a public limited company, we have more than 15 years of experience in the field. An added value that will show up in your projects.

Components

  • Laser scanners Riegl allowing the measurement up to 2 Mio points/sec with an aperture of 60-100° (FOV) and MTA technology (several pulses in the air simultaneously)

  • PhaseOne 80-150 MPix digital cameras, 55-90° aperture with color or NIR (4 band) images

  • Navigation Grade Inertial Measurement Unit (IMU) IXBLUE

  • Tri-frequency GNSS receiver (GPS-GLONASS-GALILEO)

  • Thermal camera Flir SC655

  • Up to 4 oblique cameras 18-100 Mpix

  • Up to 6 GPS-synchronized 4K videos

  • 360° panoramic camera

  • … and other sensors according to your needs.

8 systems that can be mobilized on demand

  • Helimap Sixense has 8 LiDAR-photogrammetric systems which can be operated on helicopter, ultralight or UAV, as well as a terrestrial mobile system (MLS).

  • Optimal adaptation to the customer’s needs

  • Quickly operational worldwide thanks to our redundant equipment

LiDAR and photogrammetry – powerful technologies

Orthoimage 2 cmLiDAR, colorized by intensity

Figure: High-resolution orthoimage and LiDAR point cloud with intensity information

Advantages of the LiDAR-photo combination

  • The LiDAR measures both the terrain and the vegetation that covers it, thanks to the analysis of the different echoes received for each laser pulse.

  • Very high-fidelity DTM/DSM measured and not deduced from an image correlation calculation.

  • High point density (up to >800 pts/m2)

  • The image completes the 3D measurements: high resolution orthophoto, photointerpretation

  • Colorization of the point cloud thanks to the oriented raw images.

LiDAR (Light Detection and Ranging) is a remote sensing technology in which the earth’s surface is scanned by laser pulses (electromagnetic waves). The result is a very dense and highly accurate three-dimensional point cloud.

One of the strengths of this technology lies in its ability to measure the terrain through the small gaps between the leaves of the canopy. On several occasions, this technology has even allowed us to accurately measure the terrain model under the rainforest.

Figure: Return signals according to the target hit by the pulse

Photogrammetry is a remote sensing technology based on the acquisition of digital images of the earth from different points of view. By correlation calculation, 3D models are derived as well as orthoimages (orthorectified & georeferenced images).

This technical approach generates products that are easily interpretable, even by a non-expert eye. In combination with LiDAR these technologies form the basis of modern digital cartography.

Aerial geodata acquisition – fast, accurate & flexible

Helimap System® is easily installed on different types of carriers. From a helicopter, it can even be oriented manually by the operator. This unique operating mode developed by Helimap offers a flexibility unmatched to date and guarantees homogeneity and high accuracy of the data regardless of the terrain layout. This approach is remarkable for cliff and vertical structure surveys.

  • Ideal for corridors & surfaces

  • High precision / resolution (1-10 cm)

  • Oblique or vertical operation during the same flight

  • Constant accuracy regardless of slope

  • No calibration required during installation

  • Easy and inexpensive worldwide deployment

  • Mapping of complex and inaccessible areas

  • Non-invasive survey

  • Short installation time (60 min) between the arrival of the helicopter and the flight

  • Independence of helicopter type

  • System certified (STC EASA and FAA) on AS350/355, Robinson, Bell and any helicopter equipped with a winch

Vertical
acquisition

Oblique
acquisition

Acquisition by
UAV

Acquisition by ultralight/aircraft

Terrestrial acquisition of geodata – Mobile mapping on road, rail, boat or other carrier

The Helimap System® technology can also be deployed on land vehicles, trains or boats. An operational mode that perfectly complements aerial measurements by offering new perspectives, especially for engineering structures such as underpasses or tunnels.

  • Ideal for road & rail projects

  • Very high resolution of the point cloud (>1200 pts/m2)

  • Very high precision data (<2 cm)

  • High acquisition speed (60 km/h)

  • 360° panoramic images

  • Ideal combination with an aerial survey (ALS). Our technologies will provide you with an exhaustive, precise and consistent digitization of your infrastructures

Acquisition by
land vehicle

Aerial survey performance

We like to quantify the performance of our systems based on the accuracy of the point cloud offered and the quality and resolution of the accompanying imagery.

The table below shows these values as a function of flying height for our airborne systems.

Flying height [m] 100 300 500 700
Nominal point density LiDAR max. [pt/m2] (per pass)
 800 250 150 100
Relative precision LiDAR [cm] 1 1-2 1-2 2-3
Abs. precision LiDAR XY [cm] (without GCP)
 3-5 5-7 10 15
Abs. precision LiDAR Z [cm] (without GCP)
 3 5 5-7 10
Resolution Ortho [cm] 0.5 3 5 7
Abs. precision Ortho [pix] (without GCP)
 2 2 2 2

Cartographic accuracy is given by comparing measurements (laser/photogrammetric) with ground control points (GCP). Photogrammetric accuracy can be characterized by the planimetric comparison of points on the orthophoto. The accuracy of LiDAR is divided into 2 components: relative and absolute accuracy. The relative accuracy refers to the internal noise of the point cloud (independent of the trajectory), while the absolute component refers to the control points. Accuracy is always measured on a hard surface (1 sigma).

These two terms often cause misunderstandings which are even used intentially as selling arguments by software vendors, hardware producers or service providers. We believe it is important to make our customers aware of this fact.

Accuracy (or absolute precision) quantifies the degree of conformity of a measured quantity to the true value. Precision (or relative precision) quantifies the degree of repeatability of a measurement, i.e. the degree to which a subsequent measurement will give an identical result.

Figure: Relationship between accuracy and precision of a measurement

Resolution 10 cm per pixel

Resolution 5 cm per pixel

Resolution 2.5 cm per pixel

Resolution 1 cm per pixel

Resolution 2 cmResolution 10 cm

Figure: Orthophoto 2 cm vs. 10 cm