With each aerial survey, photogrammetric software and techniques provide high quality elevation data which can be analyzed to provide useful information from farm operations and planning.
Solar Radiance Map
This map shows the calculated solar radiance on the ground for any given period of time in WH/m2 (Watt Hours per m2). This is based on an average day having a diffuse overcast for any selected time period and takes into consideration factors such as topography and latitude. In this example below, the Yellow area receives less solar radiation that the Red areas. This study area analysis was for 160 days from 1 Jan 2021. Clients only need to identify the required time period to have this analysis undertaken with their survey.
Slope is increasingly important information for regional council grazing compliance and erosion monitoring.
High quality slope maps are a powerful tool for farmers. Slope is in degrees and in the sample above, green all slopes are shown.
Specific slope angles can be displayed ie show only slopes above 15° as shown here with hill shade backdrop, second image above when hovered over after the green.
A terrain aspect map shows the cardinal aspect of a farm study.
In the example the yellow are north facing and the blue south facing. Combined with the solar radiance map this helps in identifying potential environmental influences such as wind and solar impacts.
Although of little technical value, a hill shade analysis is conducted to aid in visualisation and interpretation of above maps. It can also be used as a backdrop in other map products if requested.
Aerial photography from VizLink has many advantages for customers:
• High resolution imagery enabling accurate farm paddock digitisation (and other features such as irrigation features and troughs). This ensures our wider range of products are up to date from the start.
• An up-to-date snapshot from imagery serves as an inspection tool useful for analysis by customers on issues such as erosion identification, farm improvement monitoring, riparian compliance, tracks and vegetation maintenance.
• Imagery can often be more relatable to third parties when conducting complex on-farm operations with contractors or discussions such as banks and farm advisers.
• An aerial survey provides not just excellent aerial photographs for traditional use but advanced products as described above under 'Elevation Products.'
This is the measurable size of each pixel in an aerial photograph when related to the ground. (This has no correlation to positional accuracy which is a common assumption).
The resolution will also vary within the imagery due to factors beyond the control of the system of aircraft-camera-processing software. The most obvious cause is substantial variation in terrain. Best efforts are made with flight planning to mitigate this but customers especially on hill country, should expect to see resolution variation upon close inspection. All flights are flown to produce 5cm resolution imagery as default with lower resolution (approx. 7-10cm) used for very steep hill country.
5cm pixel size
vs 30cm Aerial Survey vs LINZ
These two images above (5cm), below (30cm) show the difference between 5cm and 30cm and ease of interpretation for identifying features on a farm such as fences and water troughs and benefit of farm updates.
Surveys are conducted with a high degree of accuracy and are fit for purpose for almost all agricultural purposes. If engineering grade accuracy is required (such as precision farming), this should include the use of ground control for accuracy assessment and confirmation.
Relative Accuracy For aerial surveys, the accuracy relative is approximately 20-30mm - this is how accurate the features you see within an aerial survey are relative to others.
Absolute Accuracy This is how accurate the entire survey is relative to the earth's surface and this can vary based on many factors. We advise .5m in the x-y (horizontal) and 2-3m in z (vertical) as a general guide.
Derived from a combination of Elevation data and Ortho imagery, the following vector products can be provided:
50cm Contours derived from the elevation data.
Troughs / Fences (paddocks) digitised from imagery.
Troughs colour coded for elevation extracted from 3d Data