NDVI FAQs

Your questions answered about NDVI Satellite Spectral Imagery.

So, what is NDVI Satellite Spectral Imagery

Sentek Technologies now offers an investigative tool exclusive to IrriMAX Live. Used by irrigators, IrriMAX Live presents a Google Map View of the selected property where water gauges and soil status are available.

NDVI images are satellite images taken throughout cropping season. This is an optional service, like the Weather forecasting service MeteoBlue (hyperlink). NDVI measures the state of plant healthy based on how the plant reflects light at certain frequencies. We utilise a range of satellite providers to get you the best images timely and cheaply. Our offering provides you with insights at 10m x 10m granularity on a frequent basis.

As customers, you can see 2-3 images per week of your crops tracking over or underperformance. This will help you tackle irrigation management, fertigation practices, crop diseases and irrigation system performance issues.

Furthermore, building up this data over time is an investment that you can realise by improving overall yield quantity or quality, reducing input costs, or expanding into new varietals or paddocks.

What crops does it support?

We support any crop with a high amount of visible foliage. Our analysis works best for regularly spaced crops. Up to 18 months of historical data can be accessed.

Where do you operate?

We can provide images around the globe. Almost all areas are suitable. We have analysed remote valleys in the South Island of New Zealand (a.k.a. Land of the Long White Cloud).

How do you capture images?

We use a third party provider to acquire and process the images and analytics to get you good value satellite imagery.

What images are you offering?

We offer a selection of images providing information on plant health. This includes

  • Normalised Difference Vegetation Index (NDVI). This gives you a simple score on how healthy your plants are.
  • Change in NDVI over time. This helps you understand how the crop is changing and whether different management strategies are working as well, or even better, than hoped.
  • Normalised Difference Moisture Index (NDMI). Describes the crop’s water stress level on a -1.0 to 1.0 scale to easily recognize the areas in a field where water stress is occuring.
  • Normalised Difference RedEdge (NDRE). An indicator of photosynthetic activity of a vegetation cover used to estimate nitrogen concentrations in plant leaves. It provides the ability to detect oppressed and aging vegetation, and to identify plant diseases.
  • Modified Adjusted Vegetation Index (MSAVI). A vegetation index that provides the ability to determine the presence of vegetation in the early stages of emergence, when there is a lot of bare soil.
  • Red-Edge Chlorophyll Index (ReCl). An index of photosynthetic activity of a vegetative cover. It provides the ability identify areas of a field that have yellowed or faded leaves which may require additional fertilizer application.

Do you charge per image or per month?

You pay for a monthly service for each paddock that you want analysed. Multiple paddocks abutting each other can generally be analysed together.

Do I get more than 1 image per week?

We provide at least 2 images per week, subject to weather conditions.

Are all these different images (NDVI, NDMI, NDRE, MSAVI, ReCI) included in the price per month?

No, every different image requires a separate 6-monthly subscription.

What is your image resolution?

Our high-resolution offering provides you with insights at 10m x 10m resolution. This means 1 ha is represented by 100 pixels. Feedback says this resolution is optimal for practical purposes.

Can you omit the cover crop from the image to just view the canopy of the main crop?

Yes. The MSAVI Service allows one to determine the presence of vegetation in the early stages of emergence, when there is a lot of bare soil.

How do I access a new image?

After your service subscription, it will automatically appear in your IrriMAX Live account under “MAP” view.

You will receive an email notifying that new images are available.

What is my minimum contract time?

Minimum contract time is 6 months. It is possible to purchase up to 18 months of historical data.

What is the turnaround time for a new image?

Historic images appear after 30 minutes, future images are ready within 3-5 days cloud cover permitting.

How do I obtain a quotation for my farm?

Demarcate your zone and select the images required and the time period. Your dealer will then provide a quote and activate your subscription once the order is confirmed.

Click here for more information.

How do I subscribe to the NDVI service?

Contact your dealer or Sentek by clicking here.

Where do I find the price list for the service?

Your dealer can provide quotations.

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