Contour Mapping Program

• How To Do Contour Mapping
• Free Contour Mapping Software

A two-dimensional contour graph of the three-dimensional surface in the above picture.A contour line (also isoline, isopleth, or isarithm) of a of two variables is a along which the function has a constant value, so that the curve joins points of equal value. It is a of the of the function f( x, y) parallel to the ( x, y)-plane. In, a contour line (often just called a 'contour') joins points of equal (height) above a given level, such as. A contour map is a illustrated with contour lines, for example a, which thus shows valleys and hills, and the steepness or gentleness of slopes. The contour interval of a contour map is the difference in elevation between successive contour lines.More generally, a contour line for a function of two variables is a curve connecting points where the function has the same particular value.The of the function is always perpendicular to the contour lines. When the lines are close together the magnitude of the gradient is large: the variation is steep.

A is a generalization of a contour line for functions of any number of variables.Contour lines are curved, straight or a mixture of both lines on a describing the intersection of a real or hypothetical surface with one or more horizontal planes. The configuration of these contours allows map readers to infer the relative gradient of a parameter and estimate that parameter at specific places. Contour lines may be either traced on a visible three-dimensional model of the, as when a photogrammetrist viewing a stereo-model plots elevation contours, or interpolated from estimated surface, as when a computer program threads contours through a network of observation points of area centroids.

In the latter case, the method of affects the reliability of individual isolines and their portrayal of, pits and peaks. Contents.Types Contour lines are often given specific names beginning 'iso-' (: ἴσος,: isos, 'equal') according to the nature of the variable being mapped, although in many usages the phrase 'contour line' is most commonly used. Specific names are most common in meteorology, where multiple maps with different variables may be viewed simultaneously. The prefix 'iso-' can be replaced with 'isallo-' to specify a contour line connecting points where a variable changes at the same rate during a given time period.The words isoline and isarithm ( ἀριθμός arithmos 'number') are general terms covering all types of contour line. The word isogram ( γράμμα gramma 'writing or drawing') was proposed by in 1889 as a convenient generic designation for lines indicating equality of some physical condition or quantity; but it commonly refers to a.An isogon (from γωνία or gonia, meaning 'angle') is a contour line for a variable which measures direction.

In meteorology and in geomagnetics, the term isogon has specific meanings which are described below. An (from κλίνειν or klinein, meaning 'to lean or slope') is a line joining points with equal slope. In population dynamics and in geomagnetics, the terms isocline and isoclinic line have specific meanings which are described below.Equidistant points A curve of equidistant points is a set of points all at the same distance from a given,. In this case the function whose value is being held constant along a contour line is a.Isopleths In geography, the word isopleth (from πλῆθος or plethos, meaning 'quantity') is used for contour lines that depict a variable which cannot be measured at a point, but which instead must be calculated from data collected over an area.

An example is, which can be calculated by dividing the population of a by the surface area of that district. Each calculated value is presumed to be the value of the variable at the centre of the area, and isopleths can then be drawn by a process of. The idea of an isopleth map can be compared with that of a.In meteorology, the word isopleth is used for any type of contour line. Meteorology.

How To Do Contour Mapping

Isohyetal map of precipitationMeteorological contour lines are based on of the point data received from. Weather stations are seldom exactly positioned at a contour line (when they are, this indicates a measurement precisely equal to the value of the contour). Instead, lines are drawn to best approximate the locations of exact values, based on the scattered information points available.may present collected data such as actual air pressure at a given time, or generalized data such as average pressure over a period of time, or forecast data such as predicted air pressure at some point in the futureuse multiple overlapping contour sets (including isobars and isotherms) to present a picture of the major thermodynamic factors in a weather system.Barometric pressure.

Video loop of isallobars showing the motion of aAn isobar (from or baros, meaning 'weight') is a line of equal or constant on a graph, plot, or map; an isopleth or contour line of pressure. More accurately, isobars are lines drawn on a map joining places of equal average atmospheric pressure reduced to sea level for a specified period of time.

In, the shown are reduced to, not the surface pressures at the map locations. The distribution of isobars is closely related to the magnitude and direction of the field, and can be used to predict future weather patterns. Isobars are commonly used in television weather reporting.Isallobars are lines joining points of equal pressure change during a specific time interval.

These can be divided into anallobars, lines joining points of equal pressure increase during a specific time interval, and katallobars, lines joining points of equal pressure decrease. In general, weather systems move along an axis joining high and low isallobaric centers.

Free Contour Mapping Software

Isallobaric gradients are important components of the wind as they increase or decrease the.An is a line of constant density. An isoheight or isohypse is a line of constant height on a constant pressure surface chart. Isohypse and isoheight are simply known as lines showing equal pressure on a map.Temperature and related subjects. The 10 °C (50 °F) mean isotherm in July, marked by the red line, is commonly used to define the border of theAn isotherm (from or thermē, meaning 'heat') is a line that connects points on a map that have the same. Therefore, all points through which an isotherm passes have the same or equal temperatures at the time indicated. An isotherm at 0 °C is called the.

The term was coined by the Prussian geographer and naturalist Alexander von Humboldt, who as part of his research into the geographical distribution of plants published the first map of isotherms in Paris, in 1817.An isogeotherm is a line of equal mean annual temperature. An isocheim is a line of equal mean winter temperature, and an isothere is a line of equal mean summer temperature.An isohel (from or helios, meaning 'Sun') is a line of equal or constant.Rainfall and air moisture An isohyet or isohyetal line (from or huetos, meaning 'rain') is a line joining points of equal rainfall on a in a given period.

The brown contour lines represent the. The contour interval is 20.Contours are one of several used to denote or and depth on. From these contours, a sense of the general can be determined. They are used at a variety of scales, from large-scale engineering drawings and architectural plans, through and, up to continental-scale maps.' Contour line' is the most common usage in, but for underwater depths on maps and isohypse for elevations are also used.In cartography, the contour interval is the elevation difference between adjacent contour lines. The contour interval should be the same over a single map.

When calculated as a ratio against the map scale, a sense of the hilliness of the terrain can be derived.Interpretation There are several rules to note when interpreting terrain contour lines:. The rule of Vs: sharp-pointed vees usually are in stream valleys, with the drainage channel passing through the point of the vee, with the vee pointing upstream. This is a consequence of. The rule of Os: closed loops are normally uphill on the inside and downhill on the outside, and the innermost loop is the highest area.

If a loop instead represents a depression, some maps note this by short lines called hachures which are perpendicular to the contour and point in the direction of the low. (The concept is similar to but distinct from hachures used in.). Spacing of contours: close contours indicate a steep slope; distant contours a shallow slope.

Two or more contour lines merging indicates a cliff. By counting the number of contours that cross a segment of a, the can be approximated.Of course, to determine differences in elevation between two points, the contour interval, or distance in altitude between two adjacent contour lines, must be known, and this is normally stated in the map key. Usually contour intervals are consistent throughout a map, but there are exceptions.

Sometimes intermediate contours are present in flatter areas; these can be dashed or dotted lines at half the noted contour interval. When contours are used with hypsometric tints on a small-scale map that includes mountains and flatter low-lying areas, it is common to have smaller intervals at lower elevations so that detail is shown in all areas. Conversely, for an island which consists of a plateau surrounded by steep cliffs, it is possible to use smaller intervals as the height increases.

Electrostatics An is a measure of electrostatic potential in space, often depicted in two dimensions with the electostatic charges inducing that. The term line or isopotential line refers to a curve of constant. Whether crossing an equipotential line represents ascending or descending the potential is inferred from the labels on the charges. In three dimensions, surfaces may be depicted with a two dimensional cross-section, showing lines at the intersection of the surfaces and the cross-section.The general mathematical term is often used to describe the full collection of points having a particular potential, especially in higher dimensional space.Magnetism. Isogonic lines for the year 2000. The agonic lines are thicker and labeled with '0'.In the study of the, the term isogon or isogonic line refers to a line of constant, the variation of magnetic north from geographic north.

An agonic line is drawn through points of zero magnetic declination. An isoporic line refers to a line of constant annual variation of magnetic declination.An isoclinic line connects points of equal, and an aclinic line is the isoclinic line of magnetic dip zero.An isodynamic line (from δύναμις or dynamis meaning 'power') connects points with the same intensity of magnetic force.Oceanography Besides ocean depth, use contour to describe diffuse variable phenomena much as meteorologists do with atmospheric phenomena. In particular, isobathytherms are lines showing depths of water with equal temperature, isohalines show lines of equal ocean salinity, and are surfaces of equal water density.Geology Various data are rendered as contour maps in,. Contour maps are used to show the below ground surface of geologic, surfaces (especially low angle ).

Use isopachs (lines of equal thickness) to illustrate variations in thickness of geologic units.Environmental science In discussing pollution, density maps can be very useful in indicating sources and areas of greatest contamination. Contour maps are especially useful for diffuse forms or scales of pollution. Acid precipitation is indicated on maps with isoplats. Some of the most widespread applications of environmental science contour maps involve mapping of (where lines of equal sound pressure level are denoted isobels ), and contamination. By and, the rate of and thus can be substantially reduced; this is especially important in zones.Ecology An isoflor is an isopleth contour connecting areas of comparable biological diversity. Usually, the variable is the number of species of a given genus or family that occurs in a region.

Isoflor maps are thus used to show distribution patterns and trends such as centres of diversity. Social sciences. From, an indifference map with three indifference curves shown. All points on a particular indifference curve have the same value of the, whose values implicitly come out of the page in the unshown third dimension.In, contour lines can be used to describe features which vary quantitatively over space.

An shows lines of equivalent drive time or travel time to a given location and is used in the generation of. An isotim shows equivalent transport costs from the source of a raw material, and an shows equivalent cost of travel time. A single production isoquant (convex) and a single isocost curve (linear). Usage is plotted horizontally and usage is plotted vertically.Contour lines are also used to display non-geographic information in economics. (as shown at left) are used to show bundles of goods to which a person would assign equal utility.

An (in the image at right) is a curve of equal production quantity for alternative combinations of, and an (also in the image at right) shows alternative usages having equal production costs.In an analogous method is used in understanding coalitions (for example the diagram in Laver and Shepsle's work ).In, an shows the set of population sizes at which the rate of change, or partial derivative, for one population in a pair of interacting populations is zero.Statistics In statistics, isodensity lines or isodensanes are lines that join points with the same value of a. Isodensanes are used to display. For example, for a bivariate the isodensity lines are.Thermodynamics, engineering, and other sciences Various types of graphs in, engineering, and other sciences use isobars (constant pressure), isotherms (constant temperature), isochors (constant specific volume), or other types of isolines, even though these graphs are usually not related to maps. Such isolines are useful for representing more than two dimensions (or quantities) on two-dimensional graphs. Common examples in thermodynamics are some types of.are used to solve.In interpreting images, an isodop is a line of equal velocity, and an isoecho is a line of equal radar reflectivity.Other phenomena.

isochasm: equal occurrence. isochor:. isodose: of radiation. isophene: biological events occurring with such as plants. isophote:. mobile telephony: andAlgorithms. finding boundaries of level sets after.History.

Edmond Halley's New and Correct Chart Shewing the Variations of the Compass (1701)The idea of lines that join points of equal value was rediscovered several times. The oldest known (contour line of constant depth) is found on a map dated 1584 of the river, near, by Pieter Bruinsz. In 1701, used such lines (isogons) on a chart of magnetic variation. The Dutch engineer drew the bed of the river with lines of equal depth (isobaths) at intervals of 1 in 1727, and used them at 10-fathom intervals on a chart of the that was prepared in 1737 and published in 1752. Such lines were used to describe a land surface (contour lines) in a map of the Duchy of Modena and Reggio by Domenico Vandelli in 1746, and they were studied theoretically by Ducarla in 1771, and used them in the. In 1791, a map of by J. Dupain-Triel used contour lines at 20-metre intervals, hachures, spot-heights and a vertical section.

In 1801, the chief of the Corps of Engineers, used contour lines at the larger scale of 1:500 on a plan of his projects for Rocca d'Aufo.By around 1843, when the started to regularly record contour lines in and, they were already in general use in European countries. Isobaths were not routinely used on until those of from 1834, and those of Britain from 1838.When maps with contour lines became common, the idea spread to other applications. Perhaps the latest to develop are and contour maps, which first appeared in the United States in approximately 1970, largely as a result of national legislation requiring spatial delineation of these parameters.

In 2007, was the first to allow users to dynamically generate elevation contour lines to be laid over oblique images.Graphical design. For features specific to, see, and.To maximize readability of contour maps, there are several design choices available to the map creator, principally line weight, line, line type and method of numerical marking.Line weight is simply the darkness or thickness of the line used. This choice is made based upon the least intrusive form of contours that enable the reader to decipher the background information in the map itself. If there is little or no content on the base map, the contour lines may be drawn with relatively heavy thickness.

Also, for many forms of contours such as topographic maps, it is common to vary the line weight and/or color, so that a different line characteristic occurs for certain numerical values. For example, in the map above, the even hundred foot elevations are shown in a different weight from the twenty foot intervals.Line color is the choice of any number of that suit the display. Sometimes a is used as well as color to set the contour lines apart from the. Line colour can be varied to show other information.Line type refers to whether the basic contour line is solid, dashed, dotted or broken in some other pattern to create the desired effect. Dotted or dashed lines are often used when the underlying base map conveys very important (or difficult to read) information. Broken line types are used when the location of the contour line is inferred.Numerical marking is the manner of denoting the values of contour lines.

This can be done by placing numbers along some of the contour lines, typically using for intervening lines. Alternatively a map key can be produced associating the contours with their values.If the contour lines are not numerically labeled and adjacent lines have the same style (with the same weight, color and type), then the direction of the gradient cannot be determined from the contour lines alone. However, if the contour lines cycle through three or more styles, then the direction of the gradient can be determined from the lines. The orientation of the numerical text labels is often used to indicate the direction of the slope.Plan view versus profile view. See also:Most commonly contour lines are drawn in plan view, or as an observer in space would view the Earth's surface: ordinary map form.

However, some parameters can often be displayed in profile view showing a vertical profile of the parameter mapped. Some of the most common parameters mapped in profile are. In each of those cases it may be important to analyze (air pollutant concentrations or sound levels) at varying heights so as to determine the air quality or on people at different elevations, for example, living on different floor levels of an urban apartment. In actuality, both plan and profile view contour maps are used in and studies. Contour map labeled aesthetically in an 'elevation up' manner.

Labeling contour maps are a critical component of elevation maps. A properly labeled contour map helps the reader to quickly interpret the shape of the terrain.

If numbers are placed close to each other, it means that the terrain is steep. Labels should be placed along a slightly curved line 'pointing' to the summit or nadir, from several directions if possible, making the visual identification of the summit or nadir easy.

Contour labels can be oriented so a reader is facing uphill when reading the label.Manual labeling of contour maps is a time-consuming process, however, there are a few software systems that can do the job automatically and in accordance with cartographic conventions, called.