DLG

A Digital Line Graph (DLG) represents digital vector data into map features. This is a regional DLG map of the suburbs of New South Wales, Australia. It divides the regions into their own separate colors.

http://www.dlg.nsw.gov.au/dlg/dlghome/dlg_regions.asp?region=region&regiontype=3

DRG

Digital Raster Graphics (DRG), are scanned raster images of USGS topographic maps. They are useful when you want to add other digital data onto a map, because it works as a digital background.This is a DRG of Bushkill, Pennsylvania.

https://www.e-education.psu.edu/natureofgeoinfo/c6_p6.html

Isopleths

An isopleth is a line on a map that connects the same amount of ratio of some type of phenomena. The above isopleth shows the hydrogen ion concentration throughout the U.S.. They measure the pH level of any given amount of surface area.

http://dwb4.unl.edu/Chem/CHEM869V/CHEM869VLinks/weather.about.com/newsissues/weather/library/weekly/aa071600a.htm

Isopachs

Isopachs show the thickness of the earth's surface. This map shows the geologic structure and seep distribution of offshore coal oil points. The colors correspond to the sediment overburden.

http://seeps.geol.ucsb.edu/pages/isopach.html

Isohyets

Isohyets are lines that connect points that receive equal amounts of rainfall. It connects different areas that have the same amount of rainfall to show a pattern. This map shows the rainfall throughout the U.S. for June 12-13, 2010.

http://www.bbc.co.uk/blogs/weather/ianfergusson/2010/06/formula-one-weather-forecast-c-1.shtml

Isotachs

An isotach is a line on a map connecting points of equal wind speed. The more dense the lines are together, the higher the wind speeds. The wind speeds in the map above are located downstream.

http://www.erh.noaa.gov/btv/events/28Oct2008/ua2.php

Isobars

An isobar is essentially a contour line of pressure. Isobars join average pressure reduced to sea level for a specific period of time.

http://www.weatheronline.co.uk/reports/wxfacts/Isobars-on-surface-maps.htm