GeoSpatial Knowledge Hive

What is Vector Data Model? Vector Data model is important concept in GIS, It consists of   point line and polygon features . Image by  Gerd Altmann  from  Pixabay   Point:   features recorded as single x, y coordinate pairs or geographic location imagesource:  www.mapwindow.org Line : features are an ordered series of connected line segments image source:  gis.stackexchange.com Polygon : Features are an ordered series of at least 3 connected lines with same start and end point. Image source: ArcMap Window 

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...

Basic Tools in ArcMap  Tools to Study : Zoom In, Zoom Out, Pan, Select Elements, and Identify. Note: When you hold the mouse point over a tool, a Tool Tip appears in a floating box to tell you the name of the tool, a short message about the use of tool appears at bottom of ArcMap window. Basic Tools in ArcMap  Basic Tools Basic Tools in ArcMap  Zooming Data Set Zooming Tool  Icon:  You can Zoom in and Zoom out Data using Zoom icon Pan :  Panning Tool You can move the map around the screen using Pan Option. Select Elements :  Select Elements tool You can use S elect Elements tool to select features Drop down give you multiple select options Select Tool and click on portion of map you want to use, Selected feature will be highlighted as shown in figure below Select Tool Showing Selected Layer  Identify Tool:  Identify Tool  Select identify tool I as shown...

Free GIS Software QGIS Known as Quantum GIS supported by Plugins easily available and frequently used world wide. Downloading Link:   http://qgis.org/en/site/      Whitebox GAT Whitebox GAT Website says " The Whitebox GAT project began in 2009 and was  conceived  as a replacement for the " Terrain Analysis System  (TAS) ". Downloading Link:  http://www.uoguelph.ca/~hydrogeo/Whitebox/download.shtml gVSIG Claim to be largest online free Geomatics Professional software. Downloading Link:   http://www.gvsig.com/en Image by  Mudassar Iqbal  from  Pixabay  

Inverse distance weighted (IDW) interpolation explicitly makes the assumption that things closer to one another are more alike than those that are farther apart.   To predict a value at unknown   location , IDW is best tool .  Image by Mojca JJ from Pixabay IDW assumes that each measured point has a local influence that diminishes with distance. It gives greater weights to points closest to the prediction location , and the weights diminish as a function of distance, hence the name inverse distance weighted . Performing IDW  Go to IDW as shown in screen below  Geostatistical  Analyst -> IDW IDW Tool in ArcMap  Creating a IDW Map Load the layer for which you have to predict data at unknown points, e.g. my data layer is  reyprecip 1. Click on the point layer on which to perform IDW in the ArcMap table of contents. 2. Start the  Geo statistical  Analyst . OR 3. Go to search type IDW select IDW Geost...

Often we need to  construct  sites for storage of water , i.e. DAM and likewise.  ArcMap can provide you with few very easy steps that scientifically selects suitable site.  Image Source: PixaBay  What these steps are? These are just few clicks that can be performed in GIS Software such as ArcMap  Adding Digital Elevation Model Converting Layer to KML Flow Direction Flow Accumulation Creating a new Shapefile Snap Pour Point Watershed Calculation Software you need for this: -          ArcGIS 10.X  Data Set: -         Any DEM ( Digital  Elevation Model Data) available online of your area of  interest .      Adding DEM Start ArcMap Right Click on layers and select Add Data Browse to folder to Add DEM data set available with name .tif or any other of your AOI. Change Symbology to your desired style just for understanding p...