How we capture and position data

Technology

GeoMap NZ uses drone mapping equipment and positioning workflows to capture high-resolution data that is practical, repeatable, and useful in the real world. Our workflow includes RTK drones, 20-megapixel mechanical shutter cameras, multispectral sensors, GNSS base and rover equipment, and ground control where the job needs it.

Drones

Our main mapping drones include DJI Phantom 4 RTK aircraft with 20-megapixel cameras and mechanical shutters. The mechanical shutter is an important part of the setup because it helps reduce rolling-shutter distortion compared with many consumer drones that use electronic shutters.

This makes the Phantom 4 RTK well suited to photogrammetry, orthomosaics and accurate drone mapping. We also use DJI RTK and multispectral equipment, allowing us to capture high-resolution aerial imagery, mapping data and vegetation-related outputs depending on the project.

GNSS & Ground Control

For projects that need stronger georeferencing, we can collect ground control points using GNSS equipment. Depending on the job requirements, we can choose how many points are needed and use them to tie the drone imagery into the correct New Zealand coordinate system.

This helps make the final map more useful for GIS, planning, design, repeatable surveys and other site work. Some jobs may only need a useful visual map, while others may need stronger absolute accuracy and properly controlled outputs.

GNSS base and rover equipment used for ground control

DJI D-RTK 2

The DJI D-RTK 2 base station communicates directly with our DJI RTK drones. This helps provide strong relative accuracy across a mapping project, especially when the drone and base station are working together as part of the same system.

When ground control points are added, the project can also be accurately georeferenced into the required coordinate system. This helps improve both relative and absolute accuracy, depending on the requirements of the job.

Ground Sampling Distance

Ground sampling distance, or GSD, describes how much ground each pixel represents in the final image. A lower GSD means a sharper and more detailed orthomosaic.

Depending on flight height, camera, site conditions and the required output, we can produce very detailed aerial maps. For some projects, drone imagery can be much sharper than general online map imagery, with ground sampling distances down around the millimetre level where the job requires it.