Satellite imaging
We rarely offer the raw satellite images. We offer orthophotos or orthomaps, or mosaics but not only them. At Zesmill, we are focused on comprehensive solutions and use various methods and approaches to extract maximum information from satellite data. We use multi-spectral, multi-temporal images of various spatial resolution, radar (SAR) images as well as stereo pairs of satellite images.
Now more than 30 companies and agencies in 19 countries are developing and operating remote sensing satellites. Since late 90’s the capability of remote sensing satellites increased dramatically. Resolution of 70, 50, and even 30 cm is now available to almost all users from commercial satellite operators. The number of spectral bands has grown from 3-4 to 20 or even 200 (hyper-spectral imaging). Satellite image interpretation has now become widespread in many areas from geology to fishery.
Multispectral satellite imagery
As is generally known, there are two prime approaches to the image interpretation: visual interpretation and mathematical methods based on digital image processing, pattern recognition, and object detection. Important data can be obtained using various methods including merging multi-spectral and multi-sensor data, parametric and non-parametric classification, sub-pixel classification, neural network modeling.
Zesmill also carries out conventional satellite image processing:
- orthorectification, cloud patching
- color balancing, haze removal, pan-sharpening
- mosaicing, orthophotomap compilation
- DEM and 3D photorealistic models generation
An important, often-overlooked approach for analyzing satellite imagery is a direct, visual interpretation by a specialist — geographer, geologist, forester, or soil scientist. It’s not the simple "meaning of the image", it goes beyond and allows to recognize spatial patterns, landscape characteristics, landforms and rock types, and indicators of past floods, landslides, volcanic activity etc., etc.
Radar satellite imagery
Zesmill’s specialists have extensive experience in processing and applying SAR (synthetic aperture radar) satellite data in various realms such as:
- rapid flood monitoring and mapping, regardless of cloud and sunlight conditions
- identification of sheet and rill erosion landforms, soil erosion mapping
- geologic and geomorphologic mapping
- mapping of forest structure and biomass across tropical and boreal forests
- oil spill detection and monitoring of marine pollution
- SAR interferometry for land subsidence monitoring (including coal mining regions and karst terrains)
- SAR interferometry for ground displacement measuring of glaciers, roads and pipeline corridors across permafrost terrains and mass movement (landslide, creep) zones
The interferometry SAR (InSAR) technique relies on the processing of two radar images of the same area that have been received from two satellite path locations. The processing of SAR images includes oversampling, co-registration, and spectral filtering (to suppress non-overlapping parts of the images spectra). The detection and the calculation (up to the centimetric accuracy) of the Earth’s surface movement that occurred between the two acquisitions can be achieved by Differential Interferometry SAR (DInSAR). DinSAR is known to be an effective method for the earth’s surface deformation monitoring including post-earthquake movements and land subsidence in mining and water-pumping areas.
Interpreting satellite images
Remote sensing, multispectral and hyperspectral spectral images especially, is used as a tool for geological mapping, structural interpretation, detection of active faults and fracture zones. Morpho-tectonic and image fusion methods aid in prospecting for hydrocarbons and ores. Aerial and satellite images have known to be a powerful tool to generate information on landforms, drainage patterns and lithology. They are routinely applied for geohazards assessments, terrain stability analysis, and industrial mineral exploration.
The high resolution SAR images offer great potential for rapid river flood and storm surge flood mapping.
Satellite imagery provides flexible instruments of monitoring many of the world’s forest conditions, including tree species identification, vegetation mapping, and deforestation assessment.
Zesmill’s team of remote sensing professionals and photogrammetrists, cartographers and geographers can guide you through satellite imagery interpretation and mapping process. We will assist you in making smart decisions which types of satellite data and interpretation approaches should be the most useful for your project.
At our gallery you can find Zesmill’s collection of remotely sensed images and maps of various landforms, landscapes, and processes in geosystems.