GeoSpatial Knowledge Hive

GDAL & OGR libraries allow you to perform various GIS operations like, Flow Direction or working with DEM few raster & vector analysis outside GIS environment. Image by  Gerd Altmann  from  Pixabay   What Knowledge one should have :  Basic Programming, Python What software you need : Python IDLE or command line, GDAL libraries files (explained later) Installation : 1- Once you have Python installed. 2- Start python IDLE to check which version of python you are using available at top as shown        Python IDLE 3- Install two files available at link below based on your version of python. Download  Link :  http://www.gisinternals.com/query.html?content=filelist&file=release-1500-gdal-2-1-2-mapserver-7-0-2.zip Install first :  gdal-201-1500-core.msi  and then:   GDAL-2.1.2.win32-py2.7.msi * Note specify the path C:\Python27\ArcGIS10.3\Lib\site-packages\ for GDAL-2.1.2.win32-py3.2....

ESRI Story Maps  Link to website: http://storymaps.esri.com/stories/2013/airports/ Image by  Emslichter  from  Pixabay   Which airport are among first 25 busiest : Hartsfield-Jackson Atlanta International Airport Beijing Capital International Airport London Heathrow Airport Tokyo International Airport O'Hare International Airport Los Angeles International Airport Paris Charles de Gaulle Airport Dallas Fort Worth International Airport Soekarno-Hatta International Airport Dubai International Airport Frankfurt Airport Hong Kong International Airport Denver International Airport Suvarnabhumi Airport Singapore Changi Airport Amsterdam Schiphol Airport John F. Kennedy International Airport Guangzhou Baiyun International Airport Madrid Barajas Airport Ataturk International Airport Shanghai Pudong International Airport San Francisco International Airport McCarren International Airport Charlotte Douglas International Airport Phoe...

How GIS started, how it evolved, what was first application of GIS  John Snow’s analysis of the cholera outbreak in London in 1854 was the first ever application of GIS. Cause of disease, was examined spatially and water well were found to be the source of spreading cholera. Although this was all human visualization and interpretation on paper maps, but it is marked as first ever GIS Application .                                                                Happy GIS Day 2016  image source : https://blogs.esri.com

China launches world largest telescope "Five-hundred-meter Aperture Spherical Telescope, or FAST" Investment :   $180 million Importance : Research, military, Space Control Research Area :  Tracing sign of intelligent extraterrestrial life.  Detecting gravitational waves.  Detecting radio emissions from stars and galaxies. image source: http://www.nydailynews.com/

Visualize View From a Particular Point Using GIS  How many places are visible from your point, e.g. you want to construct a house how many places are visible from that sight.e.g. you want to practice shooting , how many visible spots can be shot from location (A Military Application)...likewise many other interesting applications can be performed using viewshed analysis. Image by  Tim Hill  from  Pixabay Performing ViewShed Analysis   Use any GIS software, e.g. i will use ArcMap, as a first step get data set of your area. DEM (Digital Elevation Model) that gives topographic information (lat, long, height) freely available online. A shapefile of your point of sight, which you can create it easily in GIS software Example :   plne , an elevation grid; and lookouts.shp , a lookout location shapefile. Step-1 : Start ArcMap , Add data  Search for Hillshade  and  specify  files plne or your grid file  Hillshade Tool...

Free Remote sensing Software   Why so special : Free and Open Source   Additional Features: Extendable Plugins, an open source option to ERDAS IMAGINE, RemoteView, ENVI, or SOCET GXP, What Opticks say about its features:                        image source: opticks.org Free and open source Supports the following file formats: NITF 2.0/2.1, GeoTIFF, ENVI, ASPAM/PAR, CGM, DTED, Generic RAW, ESRI Shapefile, HDF5, AVI, MPEG, JPEG, GIF, PNG, BMP Zoom, pan, rotate spatially large datasets Quickly layer GIS features, annotations, results, and other information over your data to provide context Many image display controls such as colormap, histogram, transparency, etc. Support for datasets larger than four gigabytes Analysts can quickly combine steps using graphical wizards Support for processing data in its native interleave of BIP, BSQ or BIL Get  extensions  to drop in new capabili...

Assigning  image  to behave as real earth position with true coordinates(lat, long) defines all three terms but there are differences. Geo-Referencing is general term that assigns a topo sheet true coordinates. Image Registration  is assigning an image coordinates on basis of another image. It is usually an image to image Georeferencing. Image Rectification  is assigning an image coordinates on basis of another vector data or shapefile or map. Share your thoughts by commenting below. Image by Free-Photos from Pixabay

Many times you need to see how a terrain is changing in terms of slope over certain area, in GIS terms a slope is defined as  rise/run is defined as  Maximum rate of change in elevation over distance  between  cell and its eight neighbors .  Image by Elias Sch. from Pixabay Data you need: A DEM of your area easily available over internet  Start   Arccatalog ArcCatalog Window  Make Connection to Folder containing Data Set by right click on Folder Connections   at top left tab “ Folder Connections ”.     Launch Arc Map Tool Interface     Right Click Layer and select Add Data -> Add “gridfile.txt” or DEM  Click on the search icon (Ctrl+F) Ascii To Raster Tool  Using local search . Type “ ASCII to raster ” in the dialog box.  Click on function ASCII to Raster (Conversi...

Contours are a useful way to visualize topography and to create a map that can be printed in black and white, or that mimics the standard USGS topo maps. Image by TheAndrasBarta from Pixabay What you need: DEM data of your Area. Extract your area from online freely  available   DEM and select  Spatial Analyst Tools -> Surface -> Contour.  Select the inputs as follows, with a 100m or 50m contour interval: since 10 m might take time. and click  OK. Contour tool in ArcMap Output may be some thing like depending on color scheme. Go to properties and label elevation values for a good visualization. Image source:  en.wikipedia.org

Raster Calculator extracts information from a Raster Image, based on user requirements. Image by James Osborne from Pixabay Working with Raster Calculator To explore the highest elevation areas in your DEM raster e.g. select Spatial Analyst Tools à Map Algebra   Raster Calculator Tool  Raster Calculator Double click on the layer e.g. in my case it is  DEM_Layer or any raster of your choice,   to enter this into the ‘ search ’ window. Click on the “ > ” symbol e.g. and select a number less than the maximum elevation . Query can change based on your criterion.  This arithmetic raster operation will select all cells with values above the defined threshold. In the example below a threshold of 500m was used.  A new layer appears on your map. The majority of the map has a 0 value representing false (values below the threshold), and the colored region has a value of ...

Viewing Satellite Map in Arc Map " Are you  interested  to study satellite image, go to google and search for freely available online satellite images"  Image by  Daryl Govan  from  Pixabay   Download them, i have added tmrect.bil   named   imagery  here  Bands Added In ArcMap  Right Click tmrect.bil in ArcCatalog Select preview section and examine tmrect.bil What is tmrect: It is Landsat TM image with 5 bands . Right Click on tmrect and select properties All information of satellite image is available in Raster section. Explore tmrect.bil by expanding it you will see 5 bands in drop down Now Launch Arc Map Insert a new Data Frame by clicking on insert as shown Spatial Reference Dialogue  Now to Add Data Right Click Task Data Frame and click Add Data Select tmrect.bil a window “Unknown Spatial Reference” is dis...