on December 27, 2022
QGIS OpenLayers plugin needs to be reloaded
Geographic Information SystemsHow do I add OpenLayers to QGIS? The OpenLayers plugin is available through the official QGIS plugin repository HERE. You can install by simply adding it to your plugins directory, as described in a previous post, after downloading and unzipping. Select the plugin (if necessary) in the Plugins->Manage plugins … menu, as seen below. How
on December 27, 2022
Raster attribute table not showing up after exporting from R
Geographic Information SystemsHow do I view a raster attribute table? Viewing a raster attribute table Add the raster dataset containing the raster attribute table to the view. In the table of contents, right-click the raster dataset and click Open Attribute Table. How do I export a raster table? You can export a raster attribute table just as
on December 27, 2022
Comparing 2 polygon shapefiles for differences
Geographic Information SystemsHow do you compare polygons? To find the scale factor, we simply create a ratio of the lengths of two corresponding sides of two polygons. If the ratio is the same for all corresponding sides, then this is called the scale factor and the polygons are similar. How do you combine two shapefile polygons? Process
on December 27, 2022
How to remove clouds in High resolution Imagery(.5 mGeoeye)
Geographic Information SystemsWhat is a DN value in a satellite image? Each pixel also has a numerical value, called a digital number (DN), that records the intensity of electromagnetic energy measured for the ground resolution cell represented by that pixel. Digital numbers range from zero to some higher number on a gray scale. How do I remove
on December 27, 2022
How to compute distances between points and polygon borders?
Geographic Information SystemsHow do you calculate the distance between points? Distance between two points is the length of the line segment that connects the two points in a plane. The formula to find the distance between the two points is usually given by d=√((x2 – x1)² + (y2 – y1)²). This formula is used to find the
on December 27, 2022
Is there any labeling (by scale) rule of thumb in Cartography?
Geographic Information SystemsHow do you label a map in geography? Names should be legible (labels are usually as horizontal as possible with no upside-down labels) Names should be clearly associated with the features they refer to (i.e., they should be placed in an unambiguous position). There should be no overlap between names and other map content, if
on December 27, 2022
Adjusting Spatial Accuracy of Ortho Imagery in ArcGIS Desktop?
Geographic Information SystemsWhat is a block adjustment? Block adjustment is the process of computing adjustment (or transformation) based on internal relationship between overlap images, ground control points (GCPs), a camera model, a DEM, and applying the adjustment to the images within a block. How do I create an ortho mapping workspace? Quote from video: Select the imagery
on December 27, 2022
Retain the rest of the Clip (Analysis) tool in ArcGIS
Geographic Information SystemsWhat does maintain clipping extent do? MAINTAIN_EXTENT—The number of columns and rows will be adjusted and the pixels will be resampled to exactly match the clipping extent specified. NO_MAINTAIN_EXTENT—The cell alignment of the input raster will be maintained and the output extent will be adjusted accordingly. When using the clip tool in Arcmap which feature
on December 27, 2022
Which census geography boundaries do congressional districts preserve?
Geographic Information SystemsHow are U.S. congressional districts determined? After the apportionment of congressional seats among the states, which is based on decennial census population counts, each state with multiple seats is responsible for establishing congressional districts for the purpose of electing representatives. What is the relationship between the census and redistricting in the USA? The U.S. Census
on December 27, 2022
Configure GeoNetwork with postgreSQL
Geographic Information SystemsHow do I run GeoNetwork? To start the catalog: From your GeoNetwork folder location, open the bin folder and double-click start. The GeoNetwork catalog page is displayed. Once you have started the catalog, you can sign in to view additional options, search for specific resources or drill down to view detailed information about the resource.