GIS Data

Screenshot from QGIS showing the interface for adding a CSV file with a red circle around the dropdown menus for designated the X and Y fields.

X is Longitude, Y is Latitude

Caitlin Dempsey

Here are some simple strategies for remembering that X is longitude and Y is latitude in GIS.

Marina del Rey area on a county map of the state of California.

Understanding Map Scale

Caitlin Dempsey

Map scale refers to the ratio between the distance on a map and the corresponding distance on the Earth's surface.

A series of three images: top is a gray shaded relief, middle is a black and white contour image, and the bottom is a digital elevation model in shades of red with darker red indicating higher elevation.

Overview of Elevation Data

Jeff Oppong

This article reviews some of terminology and types of elevation based datasets available to GIS.

Laptop with QGIS, a desktop GIS software program

GIS 101: Learn About GIS

Caitlin Dempsey

This GIS 101 page is the launch page for accessing information about GIS and geospatial technologies on GIS Lounge.

Examples of topological errors in GIS that can occur during data creation/digitization. Image: Caitlin Dempsey

GIS Data: A Look at Accuracy, Precision, and Types of Errors

GIS Contributor

What are the types of error found in GIS data? This article reviews the difference between accuracy and precision and explains the most common types of error found in GIS data.

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