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Airborne Hyperspectral & Ground-Truthing

Hyperspectral and Ground-Truthing Whitepaper available from PAS

For a wide range of critical applications, the combination of airborne hyperspectral with ground-based non-imaging hyperspectral radiometers represents the optimal solution. A comprehensive white paper on the topic, written by Headwall Photonics and ASD Inc, part of Malvern Panalytical, is one of many available from PAS for your reference. The paper offers excellent background and specific examples of applications, procedures and results.

The worldwide precision agriculture industry is vital on so many fronts because countries depend on the revenue derived from citrus, wine-grapes, nuts and other specialty crops. Also, famine relief is the byproduct of successfully planting and harvesting crops in harsh and unforgiving climates.

Hyperspectral imaging is playing an increasingly large role here because economic and life-sustaining decisions need data that is precise and actionable. Yet, while hyperspectral images contain a wealth of data, accurate interpretation of the image requires first-hand familiarity of the surface being analysed.

In the absence of ground-truthing, remotely sensed image analysis and classification is really no more than an inference or assumption regarding earth surface conditions no matter how spatially or spectrally resolute the source image happens to be.

Ground-based reference measurements can be used to verify airborne hyperspectral data, which means the combination represents a powerful solution for the remote-sensing community. As leaders in their respective areas, Headwall and ASD understand the relationship between ground-truthing and hyperspectral.

Spectral range for ground-truthing and hyperspectral

Case study: Wyoming Assessment Project and Remote Sensing of Leafy Spurge – A.P. Williams, D.J. Kazmer

A fundamental research need in leafy spurge and invasive plant management as a whole is cost-effective, large-scale mapping of plant populations. Hyperspectral airborne data was acquired over a

25-square-mile study area in Crook County, Wyoming. ASD’s FieldSpec spectroradiometer collected ground calibration and reflectance data of leafy spurge, other vegetation and soils. These spectra were used to perform spectral mixture analysis on the hyperspectral scene. A major advantage of this technique is that it can effectively unmix a pixel and provide an estimate of the real extent of leafy spurge within the pixel.

 

To further explore these techniques and your specific application, talk to the team at PAS in Australia or New Zealand.

 

Which FieldSpec spectrometer for me?

With such an extensive range of spectral resolution options in the SWIR range, and ultra-portable VNIR-only models, it can be hard to know which of ASD’s FieldSpec 4 spectrometers and spectroradiometers will best suit your specific application. That’s where we come in.

ASD pioneered the science of field spectroscopy over 25 years ago. With a strong commitment to R&D, ASD’s enhancements to core instrument spectrometers and other critical components have dramatically improved overall performance, signal, and integration speeds compared to earlier models. 

 

A spectrometer for every occasion

The ASD FieldSpec 4 leaves the factory floor calibrated as a spectroradiometer, ready for precise radiance and irradiance measurements, but is equally suited for use as a spectrometer for accurate contact or stand-off reflectance analysis with a wide range of standard accessories.

All ASD FieldSpec spectrometers and spectroradiometers provide 3 nm spectral resolution in the VNIR (350 nm – 1000 nm) range. Four spectral resolution options are available for the SWIR (1001 nm – 2500 nm) range.

  • The enhanced 6 nm SWIR spectral resolution of the ASD FieldSpec 4 Hi-Res NG spectroradiometer provides both the sampling interval (bandwidth) and the spectral resolution to support accurate calibration and image classification analysis with the next generation high spectral resolution hyperspectral sensors.
  • With 8 nm SWIR spectral resolution the ASD FieldSpec 4 Hi-Res spectroradiometer is the instrument of choice for geological studies and atmospheric research.
  • The ASD FieldSpec 4 Standard-Res spectroradiometer, with 10 nm SWIR resolution is perfectly suited for characterizing spectral features with a resolution of 10 nm to 50 nm, which covers the technical requirements of most field researchers. The ASD FieldSpec 4 Standard-Res spectroradiometer has long been the industry’s go-to workhorse instrument for trusted field spectroscopy and the scope of potential applications is broad.
  • Because of its wide optical slit the ASD FieldSpec 4 Wide–Res spectroradiometer provides the highest signal throughput and offers the best signal to noise performance of any ASD FieldSpec model. These high throughput characteristics also benefit field measurements taken in less than optimal illumination conditions. The 30 nm SWIR resolution of the ASD FieldSpec 4 Wide-Res spectroradiometer makes it an ideal fit for applications such as vegetation analysis and vegetation indices that are characterized by broad spectral features. This instrument is also available at a significantly lower price point than other ASD FieldSpec models, which makes it an attractive option when budgets are tight.

Not all research needs are created equal and the spectral reflectance characteristics of different materials can vary greatly. Portable Analytical Solutions has seen ASD FieldSpec 4 models applied in a huge variety of situations. Speak to us about your specific application goals.

 

Precision Ag history heralds bright future

Over the past two decades, precision ag history has been marked by rapid development and positive outcomes.

Precision ag has become, well, much more precise.

According to David Mulla from the University of Minnesota, USA, in his article on Precision Ag history, “Spectral bandwidth has decreased dramatically with the advent of hyperspectral remote sensing, allowing improved analysis of specific compounds, molecular interactions, crop stress, and crop biophysical or biochemical characteristics.

Portable Analytical Solutions has relished our partnership with spectrometry specialist Headwall Photonics as we equip agribusiness with higher-quality data and more sophisticated planning and risk reduction. The result has been greater profitability, identification and mitigated risk and increased crop security.

This 2017 slideshow gallery includes actual product used by Jeff Boyer, superintendent of the Davis-Purdue Agricultural Center near Farmland, Indiana, USA.

Do any of these ‘museum exhibits’ look familiar?

If you are more interested in the future of precision ag, remote sensing or groundtruthing, speak to PAS today.

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