Category: Geographic Information Systems

Refering to 0° of longitude/latitude in a range

What is the reference line 0 for longitude called? The prime meridian The prime meridian is the line of 0° longitude, the starting point for measuring distance both east and west around Earth. The prime meridian is arbitrary, meaning it could be chosen to be anywhere. What is the range of longitude latitude? Latitude is

Removing last part of a field in QGIS attribute table, not the same length of cells

How do I delete a feature from an attribute table in QGIS? x there is also a button to delete attributes in the properties menu. First toggle editing (right click on a layer -> toggle editing) and go to the properties menu (right click -> properties or just double click). Go to the source fields

New Google Earth app max overlay texture size reduced?

What is the maximum texture size for Google Earth? If you go to Help >> About Google Earth (somewhere else on Mac), you’ll see a line about “Max Texture Size”, which indicates this limit. Most are 4096×4096 or 8192×8192, though some are lower and some are higher.  How do I scale an image overlay in

Create polygons from point dataset, where each polygon contains 3 points from the dataset

How do I create polygon from points in QGIS? Converting points to polygons can be done in just three steps: Insert the points layer: In QGIS, insert the shapefile map containing the points layer, through the menu: Layer -> Add Layer -> Add Vector Layer. Create a buffer around the points: Select from the menu:

How should ODC databases be restored and snapshot in Docker?

How to restore volume backup in docker? To restore a volume with an existing backup, you can run a new container that mounts the target volume and executes the tar command to decompress the archive into the target volume. A quick Google search returns a number of bash scripts that can help you back up

Extracting raster pixel value in ArcGIS Desktop?

How do I extract pixel values from raster in ArcGIS? To extract values from multiple rasters or a multiband raster dataset, use the Extract Multi Values To Points tool. The interpolation option determines how the values will be obtained from the raster. The default option is to extract the exact cell value at the input

How to perform reverse geocoding to custom area on the map?

How do you reverse geocoding? Reverse geocoding can be carried out systematically by services which process a coordinate similarly to the geocoding process. For example, when a GPS coordinate is entered the street address is interpolated from a range assigned to the road segment in a reference dataset that the point is nearest to. How

Converting to PDF using QGIS?

If you want a PDF you need to first create a composer window, File->New Print Composer.. . Once you have a new print composer you can add a map ( Layer->Add Map.. ) and add it by dragging an area in the composer. You can then export the composer to PDF using File->Export to PDF.. 

Postgis query for nearest neighbor returns distant coordinates

How do I find my nearest neighbors distance? The average nearest neighbor ratio is calculated as the observed average distance divided by the expected average distance (with expected average distance being based on a hypothetical random distribution with the same number of features covering the same total area). How do I find the distance between

Confusion matrix from supervised learning

A Confusion matrix is an N x N matrix used for evaluating the performance of a classification model, where N is the number of target classes. The matrix compares the actual target values with those predicted by the machine learning model.  What is confusion matrix in supervised classification? A confusion matrix is a commonly used

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