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Showing posts from April, 2020

QGIS for Spatial Data Creation

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Spatial data can be created using any GIS software, these spatial data can be created as line, point and polygon through which any feature of earth surfacecan be represented. All the linear features of can be represented by line entity, where as enclosed or area can be represented by polygon, these spatial data also called as vector data. GIS has many function and tools which can apply to create spatial data. These spatial data can be apply to many field for further studies.
In this article, spatial data creation through QGIS software is discussed. 
Line Feature creation in QGIS
Open QGIS by clicking on Start then go to All Programs and then click QGIS Desktop 3.8.3 Following window will open

Open the georeferenced toposheet via Layer then clickAdd Layer followed by Add Raster Layer

Following pop up window (Data source manager raster) will open. Browse and select the georeferenced toposheet for line features (line is used to create linear features like road, railway, drainage etc) creation …

Vector Data Model of GIS

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Vector Data ModelAs discussed in raster data article that earth surface features can be created in both raster and vector format as per requirement of user. For example wetland mapping feature such as pond can be created in both data formats, in vector as polygon and grid/pixels format in raster. 
Vector Data Model is an object based approach to the representation of real world features. This data model is best suited to represent discreet objects. In this method the entire earth surface feature including man-made and natural can be represented by only three entities in GIS. These entities name- PointLine Polygon In this all the features in which only locations is presented than Point entity used for representation in GIS software, However for representation of all linear features, line entity used in GIS tools. To represent any enclosed feature of earth and representation of any feature which has area entity, in that case, polygon entity is used in vector data. This representation also …

Raster Data Formats in GIS

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Raster Data Formats
Earth surface features including man-made features can be represented in GIS and remote sensing processes as spatial data. Spatial Data in GIS and remote sensing has two primary data formats to create information RasterVector Earliest GIS software was either Raster based or Vector based, but now most of the GIS software has data processing capabilities in both formats. Advances in computer technology have largely eliminated the boundaries between Raster and Vector data for GIS applications. An integrated raster and vector data working environment provides many more opportunities as one can combine the mathematical methods and simulations suitable for both the formats in the analysis. Both formats have their advantages and disadvantages. RASTER DATA Raster data have become the primary source of spatial data in geographic databases and are used increasingly in a wide variety of GIS applications.Raster data defined as representing earth surface feature including man-made…

Advantages of Multi Spectral Satellite Images

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Advantages of Multi Spectral/Band Satellite ImagesRemote Sensing sensors record earth's reflectance in different wavelength and these received reflectance value are processed to create separate image for each wavelength. The reflectance value stored for different wavelength in different layers, which are also called bands present in that satellite images
Multi band images also known as multi spectral satellite images. Multi band image simply define, when more than one band/spectrum and at least three wavelength data recorded by sensor to create composite of satellite images. A sensor can record several wavelength simultaneously and it is completely depend upon sensor characteristics and capabilities.
As it is already studied that sensor can record earth surface feature in different wavelength from visible spectrum to infrared spectrum.The reflectance recorded from different wavelength can be converted in to satellite image. in general three wavelength from visible i.e. blue wave …