Jump to content

Leaderboard

Popular Content

Showing content with the highest reputation since 05/28/2021 in all areas

  1. At this time, USGS Landsat 9 Collection 2 Level-1 and Level-2 data will be made available for download from EarthExplorer, Machine to Machine (M2M), and LandsatLook. Initially, USGS will provide only full-bundle downloads. USGS will provide single band downloads and browse images, and Landsat 9 Collection 2 U.S. Analysis Ready Data shortly thereafter. Commercial cloud data distribution will take 3-5 days to reach full capacity. The recently deployed Landsat 9 satellite passed its post-launch assessment review and is now operational. This milestone marks the beginning of the satellite’s mission to extend Landsat's unparalleled, 50-year record of imaging Earth’s land surfaces, surface waters, and coastal regions from space. Landsat 9 launched September 27, 2021, from Vandenberg Space Force Base in California. The satellite carries two science instruments, the Operational Land Imager 2 (OLI-2) and the Thermal Infrared Sensor 2 (TIRS-2). The OLI–2 captures observations of the Earth’s surface in visible, near-infrared, and shortwave-infrared bands, and TIRS-2 measures thermal infrared radiation, or heat, emitted from the Earth’s surface. Landsat 9 improvements include higher radiometric resolution for OLI-2 (14-bit quantization increased from 12-bits for Landsat 8), enabling sensors to detect more subtle differences, especially over darker areas such as water or dense forests. With this higher radiometric resolution, Landsat 9 can differentiate 16,384 shades of a given wavelength. In comparison, Landsat 8 provides 12-bit data and 4,096 shades, and Landsat 7 detects only 256 shades with its 8-bit resolution. In addition to the OLI-2 improvement, TIRS-2 has significantly reduced stray light compared to the Landsat 8 TIRS, which enables improved atmospheric correction and more accurate surface temperature measurements. All commissioning and calibration activities show Landsat 9 performing just as well, if not better, than Landsat 8. In addition to routine calibration methods (i.e., on-board calibration sources, lunar observations, pseudo invariant calibration sites (PICS), and direct field in situ measurements), an underfly of Landsat 9 with Landsat 8 in mid-November 2021 provided cross-calibration between the two satellites’ onboard instruments, ensuring data consistency across the Landsat Collection 2 archive. Working in tandem with Landsat 8, Landsat 9 will provide major improvements to the nation’s land imaging, sustainable resource management, and climate science capabilities. Landsat’s imagery provides a landscape-level view of the land surface, surface waters (inland lakes and rivers) and coastal zones, and the changes that occur from both natural processes and human-induced activity. “Landsat 9 is distinctive among Earth observation missions because it carries the honor to extend the 50-year Landsat observational record into the next 50 years,” said Chris Crawford, USGS Landsat 9 Project Scientist. Partnered in orbit with Landsat 8, Landsat 9 will ensure continued eight-day global land and near-shore revisit.” Since October 31, 2021, Landsat 9 has collected over 57,000 images of the planet and will collect approximately 750 images of Earth each day. These images will be processed, archived, and distributed from the USGS Earth Resources Observation and Science (EROS) Center in Sioux Falls, South Dakota. Since 2008, the USGS Landsat Archive has provided more than 100 million images to data users around the world, free of charge. Landsat 9 is a joint mission between the USGS and NASA and is the latest in the Landsat series of remote sensing satellites. The Landsat Program has been providing global coverage of landscape change since 1972. Landsat’s unique long-term data record provides the basis for a critical understanding of environmental and climate changes occurring in the United States and around the world. Data Availability Learn more about Landsat 9 data access Visit the Landsat 9 webpages to learn more about the latest mission: USGS Landsat 9 NASA Landsat 9
    4 points
  2. I just had my hands on the new GitHub feature, GitHub Copilot. It needs to install an extension in VSCode and gain access to the GitHub account. This video is just a glimpse of what it currently can do with ArcPy.
    2 points
  3. The all-virtual Esri User Conference 2021 just dropped the curtain after a four-day event. Here's whats new. Everything new explained by Jack Dangermond. ArcGIS Image is a software for remote sensing over cloud. ArcGIS Velocity gets real-time data visualization maps. ArcGIS Enterprise installation using Kubernetes. More experiments with field survey. 😑 More integrated BIM for ArcGIS. Maps SDK for game developers. Cool presentation though! What's new in ArcGIS Online. What's new in ArcGIS Pro. Moreover. ArcGIS Desktop will be supported until 2026 and Pro 2.6 in due Q2 next year. AI or GeoAI will be more ubiquitous, so will 3D mapping and sensor-based real-time data processing. I am hoping that ArcGIS Online credit cost to come down and easier to purchase.
    2 points
  4. Six years ago, we compared ArcGIS vs QGIS. The response was incredible and we thank you for that. But since then, the game has changed. Yet, the players are still the same. The Omen of Open Source GIS is back with QGIS 3. It’s up against the Pioneer of Proprietary GIS, ArcGIS Pro. Buckle up. Because today, you’re going to witness a head-to-head battle between the juggernauts of GIS software. Pick your poison. Table of Contents 1. 3D 2. Interface 3. Coordinate Systems 4. Catalog 5. Editing 6. Vector Analysis 7. Remote Sensing 8. Speed 9. Tables 10. Statistics 11. Raster Analysis 12. Networks 13. ETL 14. Scripting 15. Labeling 16. Map Automation 17. Animation 18. Map Types 19. Topology 20. Interoperability 21. Geocoding 22. Symbology 23. LiDAR 24. Map Elements 25. Metadata 26. Database 27. Web Maps 28. Errors 29. Cost 30. Extras 31. Imagery 32. File Structure 33. Community 34. Emerging Tech 35. Documentation https://gisgeography.com/arcgis-pro-vs-qgis-3/
    2 points
  5. For most uses, Google Maps is a flat, 2D app, and if your device can handle more graphics and a bit more data, you can fire up the Google Earth 3D data set and get 3D buildings. At Google I/O Google has announced a new level that turns the graphics slider way, way up on Google Maps: Immersive View. When exploring an area in Google Maps, the company says Immersive View will make it "feel like you’re right there before you ever set foot inside." The video for this feature is wild. It basically turns Google Maps into a 3D version of SimCity with AAA video game graphics. There are simulated cars that drive through the roads, and birds fly through the sky. Clouds pass overhead and cast shadows on the world. The weather is simulated, and water has realistic reflections that change with the camera. London even has an animated Ferris wheel that spins around. Google can't possibly be tracking things like the individual positions of birds (yet!), but a lot of this is real data. The cars represent the current traffic levels on a given street. The weather represents the actual weather, even for historical data. The sun moves in real time with the time of day. Another part of the video shows flying into a business that also has a whole 3D layout. All of this is possible thanks to combining the massive data sets from Google Maps, Google Earth, and Street View, but even then, this level of fidelity will be very limited by the initial data sets. Google says that at first, Immersive View will "start... rolling out in Los Angeles, London, New York, San Francisco, and Tokyo later this year with more cities coming soon." The company says that "Immersive view will work on just about any phone and device," but just like the 3D building mode, this will be an optional toggle.
    1 point
  6. if your account went to inactive members group and have limitation posting in some sub forum, and you want to reactivate your account, please post here please make sure you are : 1. Will be active in forum 2. Post valuable information 3. Occasionally log in and check updates thank you Moderator
    1 point
  7. Governments and businesses across the world are pledging to adopt more sustainable and equitable practices. Many are also working to limit activities that contribute to climate change. To support these efforts, Esri, the global leader in location intelligence, in partnership with Impact Observatory and Microsoft, is releasing a globally consistent 2017–2021 global land-use and land-cover map of the world based on the most up-to-date 10-meter Sentinel-2 satellite data. In addition to the new 2021 data, 10-meter land-use and land-cover data for 2017, 2018, 2019, and 2020 is included, illustrating five years of change across the planet. This digital rendering of earth’s surfaces offers detailed information and insights about how land is being used. The map is available online to more than 10 million users of geographic information system (GIS) software through Esri’s ArcGIS Living Atlas of the World, the foremost collection of geographic information and services, including maps and apps. “Accurate, timely, and accessible maps are critical for understanding the rapidly changing world, especially as the effects of climate change accelerate globally,” said Jack Dangermond, Esri founder and president. “Planners worldwide can use this map to better understand complex challenges and take a geographic approach to decisions about food security, sustainable land use, surface water, and resource management.” Esri released a 2020 global land-cover map last year as well as a high-resolution 2050 global land-cover map, showing how earth’s land surfaces might look 30 years from now. With the planned annual releases, users will have the option to make year-to-year comparisons for detecting change in vegetation and crops, forest extents, bare surfaces, and urban areas. These maps also provide insights about locations with distinctive land use/land cover, as well as human activity affecting them. National government resource agencies use land-use/land-cover data as a basis for understanding trends in natural capital, which helps define land-planning priorities and determine budget allocations. Esri’s map layers were developed with imagery from the European Space Agency (ESA) Sentinel-2 satellite, with machine learning workflows by Esri Silver partner Impact Observatory and incredible compute resources from longtime partner Microsoft. The Sentinel-2 satellite carries a range of technologies including radar and multispectral imaging instruments for land, ocean, and atmospheres, enabling it to monitor vegetation, soil and water cover, inland waterways, and coastal areas. “World leaders need to set and achieve ambitious targets for sustainable development and environmental restoration,” said Steve Brumby, Impact Observatory cofounder and CEO. “Impact Observatory [and] our partners Esri and Microsoft are once again first to deliver an annual set of global maps at unprecedented scale and speed. These maps of changing land use and land cover provide leaders in governments, industry, and finance with a new AI [artificial intelligence]-powered capability for timely, actionable geospatial insights on demand.” Esri and Microsoft have released this 10-meter-resolution time-series map under a Creative Commons license to encourage broad adoption and ensure equitable access for planners working to create a more sustainable planet. Users can manipulate the map layers and other data layers with GIS software to create more dynamic visualizations. In addition to being freely available in ArcGIS Online as a map service, these resources are also available for download and viewing. To explore the new 2021 global land-use/land-cover map, visit livingatlas.arcgis.com/landcover.
    1 point
  8. ah, seems i need to take the line also, before github officially launch it, LOL
    1 point
  9. maybe for interest for other users : ALOS 30m DSM data : https://www.eorc.jaxa.jp/ALOS/en/aw3d/index_e.htm https://www.eorc.jaxa.jp/ALOS/en/aw3d30/data/index.htm
    1 point
  10. TSAVI=(s(NIR-s*Red-a))/(a*NIR+Red-a*s+X*(1+s2)) NIR = pixel values from the near-infrared band R = pixel values from the red band s = the soil line slope a = the soil line intercept X = an adjustment factor that is set to minimize soil noise https://pro.arcgis.com/en/pro-app/latest/help/data/imagery/indices-gallery.htm
    1 point
  11. i think it's a old probably discontinued plugin.. some articles dates of 2012 / 2014.. probably you will have better chances with https://docs.qgis.org/2.8/it/docs/user_manual/processing_algs/otb/index.html
    1 point
  12. Download Autodesk Civil 3D https://getintopc.com/softwares/3d-cad/autodesk-civil-3d-2020-free-download-2785609/
    1 point
  13. On February 7, 2017, the twentieth and final inclination (Delta-I) maneuver of Landsat 7 took place. (Delta-I maneuvers keep the spacecraft in the correct orbital position to ensure it maintains its 10:00 am ± 15 minutes mean local time (MLT) equatorial crossing.) Landsat 7 reached its peak outermost inclination boundary of 10:14:58 MLT on August 11, 2017. Landsat 7 is now drifting in its inclination and will fall back to 09:15 am MLT by July 2021. The chart below illustrates the inclination trend from June 2014 to June 2026. The USGS and NASA are planning for Landsat 7 to remain on-station and fulfilling its current science mission until Landsat 9 completes its launch (scheduled for September 16, 2021), on-orbit checkout, and commissioning. Sometime after Landsat 9 is nominally acquiring science mission data, Landsat 7 will exit the constellation and lower its orbit by 8 km to prepare for servicing by NASA’s On-Orbit Servicing, Assembly, and Manufacturing-1 (OSAM-1) mission. The mission - the first of its kind in low Earth orbit - will provide Landsat 7 with the needed fuel for a successful decommissioning. source: https://www.usgs.gov/core-science-systems/nli/landsat/landsat-7?qt-science_support_page_related_con=0#qt-science_support_page_related_con
    1 point
  14. Let's say goodbye to Landsat 7 and say hello to Landsat 9 ! Landsat-9 will replace Landsat 7 in its orbit. The new OLI-2 and TIRS-2 sensors of the Landsat 9 will be a slight improvement from its predecessor. According to the overview, the spatial and spectral resolution remains the same - moderate spatial resolution—15 m, 30 m, and 100 m depending on spectral band—and the ability to detect the same range in intensity as Landsat 8, or better The OLI–2 will capture observa­tions of the Earth’s surface in visible, near-infrared, and shortwave-infrared bands with an improved radiometric precision (14-bit quantization increased from 12 bits for Landsat 8), slightly improving overall signal to noise ratio TIRS-2 will measure thermal radiance emitted from the land surface in two thermal infrared bands using the same technology that was used for TIRS on Landsat 8, however TIRS-2 will be an improved version of Landsat 8’s TIRS, both with regards to instrument risk class and design to minimize stray light Both OLI–2 and TIRS–2 have a 5-year mission design life, although the spacecraft has 10+ years of consumables Here are the spectral bands from OLI-2, Band 1 Visible (0.43 - 0.45 µm) 30-m Band 2 Visible (0.450 - 0.51 µm) 30-m Band 3 Visible (0.53 - 0.59 µm) 30-m Band 4 Red (0.64 - 0.67 µm) 30-m Band 5 Near-Infrared (0.85 - 0.88 µm) 30-m Band 6 SWIR 1(1.57 - 1.65 µm) 30-m Band 7 SWIR 2 (2.11 - 2.29 µm) 30-m Band 8 Panchromatic (PAN) (0.50 - 0.68 µm) 15-m Band 9 Cirrus (1.36 - 1.38 µm) 30-m Two spectral bands from TIRS-2, Band 10 TIRS 1 (10.6 - 11.19 µm) 100-m Band 11 TIRS 2 (11.5 - 12.51 µm) 100-m The good thing is Landsat 9 will image the Earth every 16 days in an 8-day offset with Landsat 8, which means increased temporal coverage of observations.
    1 point
  15. Many of Africa’s agricultural endeavors have long been tied to whims of the weather. When it rains, a country’s gross domestic product might soar. When it doesn’t rain, economies suffer. The reliance has been driven in part by the perception that dry, arid Africa has limited water resources. But a new study, years in the making, shows a different reality. As one South African scientist recently noted, if all the rainfall stopped today and for the next 100 years in Africa, there would still be plenty of water stored underneath the continent’s surface, it just wouldn’t be evenly distributed. That’s why maps are essential in showing which aquifers are vulnerable to rainfall variability. “You can imagine the possibilities,” said hydrologist Seifu Kebede Gurmessa from the University of KwaZulu-Natal in South Africa and coauthor of the study. The study, released in February, uses maps from a geographic information system (GIS) analysis to show water replenishment across the continent. It turns out that the vast majority of Africa’s countries either have high water storage or high levels of groundwater replenishment. Five countries have both. Five have neither. “We say we are prisoners of the rainfall,” Gurmessa said of Africa’s dependence on the resource for agriculture, one of the continent’s largest economic outputs. Little groundwater, proportionately, is used for irrigation currently. “How can we break that imprisonment of seasonality in the rainfall?” Groundwater use could be a buffer for the stark seasonal swings. Important Water Discoveries The report, Mapping Groundwater Recharge in Africa from Ground Observations and Implications for Water Security, was led by the British Geological Survey (BGS) and is a sequel to another of the BGS’s groundbreaking studies. Using a geographic information system to aggregate information and perform spatial analysis, the report’s authors brought old data into the present by incorporating factors that impact groundwater recharge including climate, amount of rainfall, the number of wet days in a year, land cover, vegetation health, and soil type. Nearly a decade ago, the team of international scientists created a map that showed Africa actually had a rather large volume of water hidden and stored underneath the surface. However, the researchers behind the science-shifting report and, later, the BGS’s Africa Groundwater Atlas knew that that was only part of the continent’s water story. Groundwater, like a bank account, depends on regular deposits to balance withdrawals. Once again, results of the latest research were promising. The study’s authors were able to clearly map, for the first time, which countries had sustainable resources and which ones didn’t. The countries were separated into four color-coded categories: low storage/low recharge, high storage/low recharge, low storage/high recharge, and high storage/high recharge. “That map is really key in proposing what you can do in different countries,” Gurmessa said. Click on the image to see a larger map of groundwater recharge and storage in African countries. Most countries had one or the other—high storage or high recharge. Alan MacDonald, the study’s leader and a hydrogeologist with the British Geological Survey, has called it a happy symmetry. “Still,” he said, “so many people in Africa don’t have any access to safe water.” He and the others involved hope their comprehensive research starts a conversation—just like their first report did in 2012—about what’s possible and what isn’t. For instance, what kind of access to water should be installed in a village if groundwater is plentiful but rainfall is scarce? While none of the scientists involved contemplates a pumping free-for-all that could deplete groundwater, the report does suggest the continent has been faring better than might have been expected in maintaining a healthy water supply. “It’s not all doom and gloom. It’s not all bad. In some areas, there is potential for groundwater to provide safe water supplies for many more people than currently have them,” said Kirsty Upton, who oversees BGS’s Africa Groundwater Atlas. As the report itself states, “With increasing calls to draw from groundwater storage in order to stimulate economic growth and improve food security in Africa, a more nuanced approach to water security is necessary.” Making Sustainable Plans The team’s 2012 countrywide study of the continent’s groundwater conditions—a first of its kind that attracted media attention—led government ministers to hang the study’s maps from office walls. The work also encouraged funding to help 50 Africa-based partners to create a continental groundwater atlas, with data downloaded thousands of times by nongovernmental organizations, governments, students, and researchers. The study’s research and data were also the foundation for the latest groundwater recharge report, which reveals how sustainable the water supply is. “That was the next stage for us,” MacDonald said. Ten scientists including MacDonald—five in Africa and the others from around the world—promptly got to work, pouring over 320 existing studies to find the most reliable information as well as common themes. They were about to publish in 2017 until MacDonald, noticing that some of the geolocation data for the original reference studies was off, started from the very beginning again to reanalyze the information. “You want to get this right,” he said considering the importance of the data and how far its reach may be. He recalled a moment, shortly after the 2012 study on groundwater was released, when he met two French mountaineers who had a copy of the daily newspaper Le Monde. “And there was a picture of my maps,” he said. He likened the maps, including the most recent study on replenishment, to a conversation starter. Click on the image to see a larger map of African rainfall and groundwater recharge. “If you do get a map that people are really going to look at and use, you want to make sure that you’re giving them information that is useful to them and is a gateway to more information, and not misleading people,” MacDonald said. The researchers continue to be curious too, looking at additional facets. They’re already developing their next study, looking at the quality—primarily the salinity—of Africa’s groundwater. A Promising Future For the most recent study, researchers focused on long-term average groundwater recharge rates across Africa from 1970 to 2019. They used 134 existing studies deemed the most reliable, winnowing the total down from 320 and factoring in climate and terrestrial parameters to scale for the entire continent. The process wasn’t quick, easy, or highly technical. In other projects, MacDonald said, he has used data from the National Aeronautics and Space Administration (NASA) GRACE satellite, which measures water storage changes from space, averaging over a large area (400 x 400 km) to indicate whether an area’s water has been recently depleted. “But it only gets you so far,” he said, and this time the researchers needed to look in much more detail to understand water renewability on the continent. “It was sheer old-fashioned grunt work.” He and the others went through old files and maps, some found on dusty shelves. The result of this investigation—funded primarily by the UPGro research program, whose mission is Unlocking the Potential of Groundwater for the Poor—was published in Environmental Research Letters in February. “It is really a good time to be a groundwater expert in this decade in Africa,” Gurmessa said. “The future also looks more promising.” Access to and availability of water can affect a whole host of issues, ranging from school attendance to conflict that comes from agriculture workers migrating from one rural area to another, not to mention overall human health. Water is tied to everything in one’s life, he pointed out. source: https://www.esri.com/about/newsroom/blog/africa-groundwater-mapping/
    1 point
  16. Classification of precipitation change regimes based on changes in the precipitation mean state and variability. Shading indicates the ratio of change in precipitation variability and mean precipitation. Climate models predict that rainfall variability over wet regions globally will be greatly enhanced by global warming, causing wide swings between dry and wet conditions, according to a joint study by the Institute of Atmospheric Physics (IAP) of the Chinese Academy of Sciences (CAS) and the Met Office, the UK's national meteorological service. This study was published in Science Advances on July 28 2021. Increased rainfall leads to floods, less rainfall to drought. Researchers realized decades ago that global warming drives increased rainfall on average. How this increase is delivered in time matters enormously. A 2 to 3 percent increase of annual precipitation uniformly spreading across the year does not mean much, but if it falls in a week or a day, it will cause havoc. Using large ensembles of state-of-the-art climate model simulations, this study highlights the increase in rainfall variability across a range of time scales from daily to multiyear. Scientists have found that in a future warming world, climatologically wet regions (including the tropics, monsoon regions and mid- to high-latitudes) will not only get wetter on average, but also swing widely between wet and dry conditions. "As climate warms, climatologically wet regions will generally get wetter and dry regions get drier. Such a global pattern of mean rainfall change is often described as 'wet-get-wetter'. By analogy, the global pattern of rainfall variability change features a 'wet-get-more variable' paradigm. Moreover, the global mean increase in rainfall variability is more than twice as fast as the increase in mean rainfall in a percentage sense," said Zhou Tianjun, corresponding author of the study. Zhou is a senior scientist at IAP. He is also a professor at the University of Chinese Academy of Sciences. The enhanced rainfall variability, to a first order, is due to increased water vapor in the air as climate warms, but is partly offset by the weakening circulation variability. The latter dominates regional patterns of change in rainfall variability. By considering changes in both the mean state and variability of precipitation, the research provides a new perspective for interpreting future precipitation change regimes. "Around two-thirds of land will face a 'wetter and more variable' hydroclimate, while the remaining land regions are projected to become 'drier but more variable' or 'drier and less variable'. This classification of different precipitation change regimes is valuable for regional adaptation planning," said Zhang Wenxia, lead author of the study. "The globally amplified rainfall variability manifests the fact that global warming is making our climate more uneven—more extreme in both wet and dry conditions, with wider and probably more rapid transitions between them," said Kalli Furtado, expert scientist at the Met Office and second author of the study. "The more variable rainfall events could further translate into impacts on crop yields and river flows, challenging the existing climate resilience of infrastructures, human society and ecosystems. This makes climate change adaptation more difficult." source: https://phys.org/news/2021-07-rainfall-increasingly-variable-climate.html
    1 point
  17. A global land cover GeoTIFF was recently released by Impact Observatory (IO) and Esri. To create this geospatial layer, hundreds of thousands of satellite photos were classified into ten unique land use/land cover (LULC) classes using a deep learning model in partnership with Microsoft AI for Earth. Sentinel-2 imagery was used to divide the world into ten categories of land use cover: Water (areas that are predominately water such as rivers ponds, lakes, and ocean) Trees (clusters that are at least 10 meters high) Grasslands such as open savannas, parks, and golf courses Flooded vegetation such as wetlands, rice paddies, and Crops Scrubland Built areas such as urban/suburban, highways, railways, and paved areas. Bare ground in areas with little or no vegetation such as exposed rock/soil and sparsely vegetated deserts. Permanent snow and ice areas Cloud cover areas where the persistent cloud cover prevents an analysis of the underlying land cover. The end product is a 10-meter resolution GeoTiff that the developers have released under a Creative Commons 4.0 license. The machine learning model was run on multiple dates throughout the year with the results folded into one consolidated layer to represent land use cover for the year 2020. The 2020 Esri Land Cover dataset can be browsed using Esri’s online Map Viewer. Users can also access the full global GeoTIFF zip file or use Esri’s tool for accessing the land use data by tile.
    1 point
  18. The topic that counts is interesting and that is the way to do good work when we have to present a project. Unfortunately for us that we do not have a solution like Erdas. The Hexagon company evolves every day and presents many solutions but at the business level, it talks about opportunities for students but I do not know their prices. Esri at least provides an opportunity and we know it costs. Thanks for your comments and any ideas to bring that workflow into cheaper or open access solutions. Lurker successes.
    1 point
  19. there is also a new tool in arcgis pro called "Pixel Editor" if you need to correct the values for this tool you need the Image analyst license. https://pro.arcgis.com/en/pro-app/help/analysis/image-analyst/editing-elevation-pixels.htm depending on your task or your licence you can also use the "Raster Calculator" (needs spatial analysis). For example if you have a polygon with the elevation data and you want to substitute the values on your raster (polygon to raster, then use the conditional function > con() https://desktop.arcgis.com/en/arcmap/10.3/tools/spatial-analyst-toolbox/con-.htm
    1 point
  20. Follow this one: https://gis.stackexchange.com/questions/182359/is-it-possible-to-install-geoserver-on-google-cloud One method even has a video describing the installation.
    1 point
  21. try on https://www.acugis.com/acugis-suite/ not free but quite reasonable price, because cloud maintenance need cost
    1 point
  22. hi, why do you use landsat 7 and not landsat 8? and with witch software? here you can see the band combination for landsat 7 and 8 http://landsat.usgs.gov/L8_band_combos.php http://web.pdx.edu/~emch/ip1/bandcombinations.html so the band combination for TM is 1-4-7 in Landsat 7, the combination can be 7-6-4 http://www.harrisgeospatial.com/company/pressroom/blogs/tabid/836/artmid/2928/articleid/14305/the-many-band-combinations-of-landsat-8.aspx you load every single band in ArcGIS and you do a combination then do a classification (supervised or unsupervised) Two major categories of image classification techniques include unsupervised (calculated by software) and supervised (human-guided) classification. Unsupervised classification is where the outcomes (groupings of pixels with common characteristics) are based on the software analysis of an image without the user providing sample classes. The computer uses techniques to determine which pixels are related and groups them into classes. The user can specify which algorism the software will use and the desired number of output classes but otherwise does not aid in the classification process. However, the user must have knowledge of the area being classified when the groupings of pixels with common characteristics produced by the computer have to be related to actual features on the ground (such as wetlands, developed areas, coniferous forests, etc.). Supervised classification is based on the idea that a user can select sample pixels in an image that are representative of specific classes and then direct the image processing software to use these training sites as references for the classification of all other pixels in the image. Training sites (also known as testing sets or input classes) are selected based on the knowledge of the user. The user also sets the bounds for how similar other pixels must be to group them together. These bounds are often set based on the spectral characteristics of the training area, plus or minus a certain increment (often based on "brightness" or strength of reflection in specific spectral bands). The user also designates the number of classes that the image is classified into. Many analysts use a combination of supervised and unsupervised classification processes to develop final output analysis and classified maps. (source : https://articles.extension.org/pages/40214/whats-the-difference-between-a-supervised-and-unsupervised-image-classification)
    1 point
  23. It is in technical preview right now. I am afraid they might start charging as soon as the final version comes out.
    0 points
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.

Disable-Adblock.png

 

If you enjoy our contents, support us by Disable ads Blocker or add GIS-area to your ads blocker whitelist