Prima di iniziare
Different satellites carry different sensors - therefore, they vary in provided services. The well-known value is a spatial resolution, which refers to the size of one pixel on the ground. It can be increased by pansharpening, a technique of merging high-resolution panchromatic (grayscale) with low-resolution colored images. Satellites with high-resolution cameras cover just small areas and they have a long revisit time, which is a crucial aspect for some types of analysis. Some projects require data in other spectral bands, such as infrared for NDVI application for agriculture. The data also vary in level of processing: from raw sensor data to calibrated images with correct location information. MapTiler helps to turn an image into the final zoomable map.
Scarica le immagini
Free data, mainly from NASA and ESA, can be found in specialized catalogs, where users search based on the area of interest, required resolution, or capture date. The most popular satellites with free data in the visible spectrum are Landsat-8 and Sentinel-2. They can be found in the USGS Earth Explorer catalog.
While browsing is without restrictions for anyone, downloading requires login. After filling in a very detailed form, you will get access to a high number of scientific data from satellites.
In the Search criteria, define your area of interest either by looking up an address or by defining a polygon. This can be done simply by clicking on the map or by uploading a shapefile or KML file. You can also restrict your search by date. In the Data Sets tab, you can select the required satellites. In your case, Sentinel-2 and Landsat 8 are the correct options. In Additional criteria, you can impose extra limitations like cloud coverage. Finally, the Results tab shows founded images, and you can switch between results from selected satellites. Each entry has a preview and, for logged users, also a download option.
Trascinando e rilasciando le immagini in MapTiler Engine e impostando alcuni parametri, è possibile ottenere un risultato sotto forma di mappa online. Questa può essere caricata su servizi cloud come MapTiler Cloud, Amazon S3, Microsoft Azure o Google Cloud, e sui propri server o integrata nella propria applicazione.Scarica MapTiler Engine
Risorse satellitari online
- USGS Earth Explorer provides access to NASA Landsat images, which covers the whole world, including photos up to 40 years old, and other data like Digital Elevation Model
- Snapsat is an easy-to-use browser for Landsat 8 satellite imagery. The results are sorted based on cloud coverage or date; users can compose their own images from 11 bands.
- Libra is an easy-to-use browser for open Landsat 8 satellite imagery. There is a simple filter option.
- Sentinels Scientific Data Hub è il luogo di download dei dati di Sentinel-2, che ha una risoluzione spaziale di 10 metri, un periodo di rivisitazione di cinque giorni e fornisce dati in 12 bande spettrali.
- NOAA CLASS is a great source of atmospheric and environmental data from NPP, JPSS, GOES-R, Jason-3, and NEXRAD projects.
- Earth Observation Link (EOLi) is a bit outdated Java program, but it provides all the functionality of online catalogs. It includes data from Envisat, ERS, IKONOS, DMC, ALOS, SPOT, Kompsat, Proba, IRS, and SCISAT.
- NASA Reverb abounds with a huge diversity of satellite data you can search and download.
- National Institute for Space Research provides imagery of Earth Resources Satellite 2, a joint venture satellite project made by Brazil and China.
- Bhuvan Indian Geo-Platform of ISRO is an Indian project which offers data from IMS-1, Cartosat, OceanSat, and ResourceSat satellites. However, most of the images cover India only.
- NOAA Data Access Viewer provides a download place for satellite imagery, land cover, and elevation data for the United States.
- VITO Vision provides low-resolution imagery of vegetation.
- NOAA Digital Coast is a place to go for free satellite imagery of seashores.
- Global Land Cover Facility provides global vegetation imagery from Landsat, MODIS, and AVHRR.
- If your demand is not satisfied by free providers, you can try products from commercial companies. Some of them provide free samples of their products: DigitalGlobe Free Product Samples or Geo-Airbus.
Elaborazione di big data con MapTiler Cluster
L'elaborazione di grandi volumi di dati può essere eseguita in parallelo su più computer, utilizzando MapTiler Cluster per ridurre significativamente i tempi di rendering.Per saperne di più