Dinesh Shrestha

Remote Sensing Scientist at KBR Inc. the contractor to the United States Geological Survey (USGS).

The use of Support Vector Machines (SVM) for Land Cover Mapping from Remote Sensor Imagery

Land Cover Mapping: Land cover mapping has become one of the essential studies in environmental and remote sensing science.  No later than the introduction of remote sensing, the lad cover mapping has gained popularity among scientists and researchers. Land cover mapping is a technique of mapping the features on the earth’s surface using remote sensing …

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What is an Error Matrix? What is Error Budget Analysis?

Introduction Error matrix is the most commonly used accuracy assessment tool mostly during Land Cover Classification. In accuracy assessment, typically the land cover classification in the map is compared to the true land cover condition. This is done using the ‘ground truth’, or ‘reference data’.  Since the ground truth data is not practically attainable, researchers …

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What is an Accuracy Assessment? Why is it necessary?

Introduction The application of GIS in Remote Sensing, particularly the land cover classification has contributed a lot in the scientific community (read: What is the importance of GIS (Geographic Information Science) in Remote Sensing?) and at the same time has led to the need for accuracy assessment of the products because most scientists believe that …

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What is a Map Projection? What are different Map Projections used in GIS?

Earth is a spherical (not exactly but let’s consider!) surface. This spherical surface is also termed as spheroid or ellipsoid. It has always been a challenging job to specify the location and shape of a particular feature on the earth surface. In order to solve this issues the geographer and cartographer came up with an …

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Want to become GIS expert: Master these 20 Essential GIS Skills.

Background This article is inspired by a book by Gina Clemmer, “The GIS 20 Essential Skills” published by ESRI in 2017. This book offers an activation code for free GIS trail for 180-days, so it’s worth buying this book. First thing first, you need to have basic knowledge on GIS in order to learn these …

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What are the similarities and differences between Shapefile and Feature Class?

It has always been a popular question – What are the differences between shapefile and feature class? Here, are differences and similarities between Shapefiles and Feature class. What are feature classes? A feature class is a collection of geographic features that share the same geometry type (such as point, line, or polygon) and the same …

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What are Shapefiles?

Definition Shapefiles are spaghetti data models containing a features class composed of points, lines, or polygons, but never a mixture. The attributes are stored in dBase file. Shapefiles can store multipart features, in which a single feature includes multiple objects. Shapefile components and file extensions Shapefiles are stored in three or more files that all …

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What are Feature Classes?

Definition A feature class is a collection of geographic features that share the same geometry type (such as point, line, or polygon) and the same attribute fields for a common area. Examples: streets, well points, parcels, soil types, and census tracts etc. A feature class can contain only one kind of geometry—point, line, or polygon …

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What is an Atmospheric Correction and why is it necessary?

What is an Atmospheric Correction? As name suggest, atmospheric correction is the process of removing the effects of the atmosphere on the reflectance values of remotely sensed images. The atmospheric effects may be referred to as presence of gas absorption, molecule and aerosol scattering that can influence incident and reflected radiation the atmosphere can have …

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Important Sites to Download Freely Available GIS Datasets – In the USA

Forewords As a researcher, it is always troublesome to find right datasets for right projects. It could be more infuriating when you lose the websites that you’ve been downloading the data from. The best idea is to bookmark the important websites so that you will never loose them. Check these websites to “Download GIS Data by …

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