What does DLG stand for GIS?

digital line graph
DLG. [data models] Acronym for digital line graph. Data files containing vector representations of cartographic information derived from USGS maps and related sources. DLGs include information from the USGS planimetric map base categories such as transportation, hydrography, contours, and public land survey boundaries.

What is a DLG map?

A Digital Line Graph (DLG) is a cartographic map feature represented in digital vector form that is distributed by the U.S. Geological Survey (USGS). DLGs are collected from USGS maps and are distributed in large-, intermediate- and small-scale with up to nine different categories of features, depending on the scale.

What kinds of data are contained in the USGS DLG files?

USGS File Types DIGITAL LINE GRAPH (DLG) are vector files generated on traditional paper topographic maps. For example, this includes township & ranges, contour lines, rivers, lakes, roads, railroads and towns.

What is DRG in GIS?

DRG. [data models] Acronym for digital raster graphic. A raster image of a scanned USGS standard series topographic map, usually including the original border information, referred to as the map collar, map surround, or marginalia.

How are DLGs made?

DLGs exist at three scales: small (1:2,000,000), intermediate (1:100,000) and large (1:24,000). Large-scale DLGs are produced in tiles that correspond to the 7.5-minute topographic quadrangles from which they were derived. Layers and contents of large-scale Digital Line Graph files.

Where can I buy digital elevation models?

5 Free Global DEM Data Sources – Digital Elevation Models

  • Space Shuttle Radar Topography Mission (SRTM)
  • ASTER Global Digital Elevation Model.
  • JAXA’s Global ALOS 3D World.
  • Light Detection and Ranging (LiDAR)
  • Mars Orbiter Laser Altimeter (MOLA)

What is line graph in cartography?

Line graphs are biaxial graphs which are drawn on a reference frame of two mutually orthogonal axes. • In these graphs the points are plotted by means of rectangular coordinates with reference to a point of origin at which the x- axis (horizontal line) and y-axis (vertical line) intersect at right angles.

What is the most accurate elevation data?

ALOS World 3D is a 30-meter resolution digital surface model (DSM) captured by the Japan Aerospace Exploration Agency (JAXA). Recently, this DSM has been made available to the public. The neat thing about is that it is the most precise global-scale elevation data now.

What are the two types of line graph?

The following are the types of the line graph. They are: Simple Line Graph: Only one line is plotted on the graph. Multiple Line Graph: More than one line is plotted on the same set of axes.

How accurate is LiDAR for elevation?

Airborne laser scanning systems (commonly referred to as light detection and ranging or lidar systems) can provide terrain elevation data for open areas with a vertical accuracy of 15 cm. Accuracy in heavily forested areas has not been thoroughly tested.