Spectral imaging has become a treasure trove in many fields, from agriculture to environmental management. Hyperspectral and multispectral imaging are at the forefront of this technology.
Hyperspectral imaging captures ultra-fine spectral details in hundreds of narrow bands, making complex material analysis and target detection possible. Though powerful, this approach requires complex data processing and expert interpretation.
Unlike hyperspectral imaging, multispectral imaging achieves simplicity, cost-effectiveness, and faster data output by capturing fewer, broader spectral bands at the expense of some spectral resolution.
The main difference between hyperspectral and multispectral technologies lies in the number of bands captured, including the narrowness of these bands (spectral resolution) and the electromagnetic radiation spectrum included in each band.
As its name suggests, hyperspectral imaging (HSI) covers more spectral bands than multispectral imaging (MSI).
Multispectral satellite constellations collect data across a limited portion of the electromagnetic spectrum (five to ten bands); typically, this is the RGB (red, green, blue primary colors) and some infrared bands. Hyperspectral satellites can distinguish thousands of individual spectral bands.
Hyperspectral and multispectral imaging satellites primarily operate in LEO (Low Earth Orbit). MSI satellites, like Landsat, Sentinel-2, and EOS SAT-1, provide essential information for distinguishing land cover features and landscape patterns.
Hyperspectral sensors can see more information, making it possible to identify and quantify materials. While the additional bands do make it easier to discern more details, they also require the elimination of redundant data and make analysis more complex and expensive.
Spectral and Spatial Resolution
HSI provides high spectral resolution as it precisely distinguishes wavelengths. Meanwhile, it is associated with low spatial resolution. Compared to hyperspectral, multispectral sensors are more suitable for applications that require general spectral data, as they operate in wider and fewer bands.
Data Size and Processing
Due to the enormous amount of detailed data produced by hyperspectral remote sensing, data processing requires complex and resource-intensive methods. For correct interpretation, you need specialized software and knowledge.
Compared to hyperspectral, multispectral image data is quicker and simpler to process due to fewer spectral bands. This is effective in scenarios requiring fast or real-time analysis. Nowadays, the advent of widely available, user-friendly software and resources has made MSI analysis more accessible, enabling multispectral remote sensing applications to be applied across various industries and applications.
Cost
The complexity of sensors and the subsequent data processing define the pricing of the two options. Compared to multispectral, hyperspectral imaging is generally more expensive and resource-intensive. The former is a more economical choice unless precise data, such as material data, is required.
Dependence on Atmospheric Conditions
Both hyperspectral and multispectral remote sensing are susceptible to environmental conditions and require thorough calibration. For this reason, HSI should only be used in controlled environments or for very specific scientific research. Multispectral imaging does not have these limitations; it performs well across a wide range of environments with less atmospheric interference, thus offering more potential uses.
HSI has a vast untapped potential but is currently primarily used for scientific research. On the other hand, MSI is sufficient to meet the needs of ordinary users in a wide range of remote sensing applications.
Hyperspectral and multispectral imaging have many practical applications in various fields, including agriculture, environmental research, disaster management, and more.
While hyperspectral images are more commonly used in geology and mineral development to gather information about materials, MSI has wide applications in agriculture and forestry to collect data about the Earth's surface, its cover, and change patterns.
Precision Agriculture
Compared to hyperspectral image data, multispectral image data has accessibility and ease of analysis, making it a common choice for agricultural consultants and other agricultural business participants in precision agriculture solutions. High-resolution MSI supports farmers in crop health monitoring, pest identification, precision irrigation, and variable-rate fertilization. Additionally, MSI can also aid in sustainable land management by distinguishing different crops and vegetation cover from bare ground.
Vegetation Analysis
Many aspects of vegetation cover are studied using hyperspectral and multispectral image data. Particularly, vegetation change detection using MSI is crucial for monitoring changes in plant cover over time in specific regions. Satellite images can also be used to assess plant diversity as part of biodiversity studies.
Environmental Monitoring
MSI is ideal for detecting changes in land use and vegetation cover and assessing the health of different ecosystems, such as forests and wetlands. Hyperspectral images may be helpful when mapping hydrological structures. Researchers are increasingly turning to hyperspectral and multispectral remote sensing for better monitoring water bodies, water pollution, and changes in water quality.
Disaster Management
Remote sensing technology is heavily relied upon for emergency preparedness and disaster assessment. MSI is highly beneficial in assessing damage from earthquakes, floods, hurricanes, and other natural or man-made disasters. Additionally, by providing near-real-time data from the most remote and underdeveloped areas, it helps coordinate disaster response and distribution. For example, in 2023, multispectral image data was widely used to analyze and mitigate natural disasters.
Forestry
Advances in hyperspectral and multispectral sensor technology have greatly simplified and improved the accuracy of remote detection of tree species. In assessing forest health, monitoring deforestation, and sustainable forestry management, MSI (multispectral imaging) is indispensable. By closely monitoring changes and deviations in plant health, spectral imaging plays a crucial role in detecting areas at risk of wildfires.
When choosing between hyperspectral and multispectral imaging, you can consider evaluating which is more important for the task: higher spectral detail or operational efficiency.
Hyperspectral sensors detect numerous narrow bands, providing extensive information about the unique spectral characteristics of different materials. However, such high spectral resolution requires greater computational power, complex data processing, and expertise to interpret the results.
Due to the practical balance achieved between spectral resolution and operational efficiency, multispectral imaging often outperforms hyperspectral imaging.
Using MSI, you can enjoy a more economical solution as it does not require as much data storage and computational complexity. At the same time, high-resolution multispectral satellite images can provide detailed visualization of surface cover.
When a bird-eye view is sufficient, and ultra-fine spectral discrimination is not needed, multispectral imaging is a practical solution to save funds and accomplish the task.