Tutorials

Shapefile Conditional Columns in GeoPandas and Numpy

Shapefile Conditional Columns in GeoPandas and Numpy

While most shapefiles acquired from various sources are fairly ready to use with little or no edits, other uses may dictate that changes are made to a shapefile. One such instance is the need to add a column to a shapefile based on some condition. In most instances, the conditions may be too complicated such…

Importing vector and raster data in the Google Earth Engine.

Importing vector and raster data in the Google Earth Engine.

Vector and raster data formats are used in analysis in the Google Earth Engine. Vector data can be in formats such as shapefile, which is the most commonly used, Digital Line Graph (DLG), Keyhole Markup Language (KML), GeoJSON (Geographic JavaScript Object Notation), among others. Raster data formats on the other hand can be in GeoTIFF,…

Plotting a Digital Elevation Model Profile in GEE

Plotting a Digital Elevation Model Profile in GEE

A digital elevation model is a representation of the bare ground topographic surface of the earth exclusive of trees, buildings and other objects on the earth’s surface. Digital elevation models are extracted from sources such as topographic maps, high resolution LiDAR (Light Detection and Ranging) or IfSAR (interferometric Synthetic Aperture Radar). However, LiDAR and IfSAR…

Using Landsat 8 Image To Perform Cloud Masking on GEE

Using Landsat 8 Image To Perform Cloud Masking on GEE

Landsat 8 images are widely used for a variety of applications. However, cloud and cloud shadow cover issues are still a challenge. Clouds and cloud shadow decrease accuracy of remote sensing application results because they obscure the land surface, and the brightening effect of clouds and the darkening effect of cloud-shadow’s influence the reflectance capability…

Computation of NDBI in Google Earth Engine

Computation of NDBI in Google Earth Engine

What is NDBI? Normalized Difference Built-up Index (NDBI) is a spectral index used to analyze built-up areas. This index uses two bands: the short-wave infrared (SWIR) and the near infrared (NIR). Areas with more built-up structures reflect shortwave-infrared (SWIR) more while areas with less built-up have a low Near-Infrared (NIR) reflectance. NDBI values range from…

Computing MNDWI using Sentinel 2 on Google Earth Engine

Computing MNDWI using Sentinel 2 on Google Earth Engine

What is MNDWI? Modified Normalized Difference Water Index (MNDWI) is a spectral index used to analyze water bodies such as rivers, lakes and dams especially in built-up areas since it can reduce or even remove built-up land. This index uses two bands:  green and short-wave infrared (SWIR). MNDWI values range from -1 to +1 where…

Google Earth Engine: Applying joins between features

Google Earth Engine: Applying joins between features

Joins are used to combine elements from different collections (e.g. Image Collection or Feature Collection) based on a condition specified by an ee.Filter. The filter is constructed with arguments for the properties in each collection that are related to each other. Specifically, left Field specifies the property in the primary collection that is related to…

Computing a Buffer in Google Earth Engine.

Computing a Buffer in Google Earth Engine.

Google Earth Engine supports a wide variety of geometric operations. These include operations on individual geometries such as computing a buffer, centroid, bounding box, perimeter, convex hull, etc. A buffer is a zone that is drawn around a point, line or polygon that includes all the area within a specified distance of the geometric feature….

Preview of an Image Collection Using a Time Series Animation.

Preview of an Image Collection Using a Time Series Animation.

Images composing an ImageCollection can be visualized as either an animation or a series of thumbnails referred to as a filmstrip. These methods provide a quick assessment of the contents of an ImageCollection and an effective medium for detecting spatiotemporal change. This article focuses on how to prepare an Image Collection for visualization, provide example…

Performing Pan-Sharpening on Landsat 8 image in Google Earth Engine.

Performing Pan-Sharpening on Landsat 8 image in Google Earth Engine.

Pan-sharpening is the process of enhancing a low resolution multiband image by fusing it with a corresponding high spatial resolution panchromatic (single band) image. The resulting multiband image has a resolution similar to the panchromatic image since the two rasters fully overlap. In Google earth engine, pan-sharpening process is made possible by using two methods;…

Burn Severity Mapping Using Landsat and  Sentinel 2 Imagery.

Burn Severity Mapping Using Landsat and Sentinel 2 Imagery.

Burn severity refers to the effects that fire intensity has on the functioning of an ecosystem in the area that has been burnt.  It is the degree to which an ecosystem has been disturbed due to fire. The degree to which an area has been affected by fire can be measured using the Normalized Burn…

Air Quality Monitoring Using Sentinel 5 Precursor TROPOMI.

Air Quality Monitoring Using Sentinel 5 Precursor TROPOMI.

Air pollution is the presence of substances suspended in the atmosphere that are considered harmful to the health of human beings and other living things. Some of the pollutants include harmful gases such as nitrogen dioxide, Sulphur dioxide and carbon monoxide. These gases may be released into the atmosphere through either natural sources or anthropogenic…