In the plans it is necessary to be aware that the lines that are darker are known as master contour lines. This term includes the distance that exists between what are several imaginary planes that come to cut and that is always the same for a given map. Not less relevant is taking into account what is known as equidistance between contour lines. In the same way, that the line of maximum slope that exists between two contour lines is the one that joins them through what is the shortest distance. It is important to know that the contour lines neither intersect nor intersect. It also responds to the name of isohipsa.
CONTOUR LINE DEFINITION SERIES
In addition to everything indicated, we cannot ignore another series of relevant aspects about the contour line, such as the following:
When contour lines, colored differently, are projected onto the map, rendering occurs. The contour line is the figure formed by each of these planes that cuts the ground. These planes are at a certain distance from each other. To achieve the representation of the contour lines, what is done is to obtain planes parallel to each other through cuts on the surface of the ground. The difference in altitude between two successive contour lines is constant and is linked to the scale used on the map. The contour lines, in this framework, reflect the representation of a horizontal section of the relief. Is science build maps by determining the magnitude and shape of regions of the globe. These lines are generally drawn in blue to reflect the depths of the ocean and glaciers, and in sienna with shading to mark the height of the terrain. It should be remembered that topography is the discipline focused on the description and delineation of the surface of a terrain.Ī contour line, therefore, is the line that joins the points of a map that have identical altitude. Figure 5 shows the result of contour lines.įigure 5.The idea of Level curve It is used in the field of topography with reference to the line that is formed by those points of the land that are located at the same height. The result can be seen in the QGIS map canvas without closing the contour plugin window, therefore we can switch back to change a parameter if the result not looks as we want. Furthermore the color graduation for the contour lines can be changed by selecting a color ramp for the output contour lines.Ħ. In the next setting we can specify the precision and unit for the contour label.
The output will be written to memory, so we need to export to it to a GIS file to keep it permanently.ĥ. symbology On a topographic map, concentric contour lines drawn with hachures to indicate a closed depression or basin. Moreover the interval can be edited manually by double click the interval number.Ĥ. We can tweak the number if the interval is not correct. When we set the calculated number, the contour interval can be seen in the right list. Then the number of contour line will be: maximum elevation/contour interval. For example if we want to make a contour map in 100.000 scale, then the contour interval will be 1/2000 x 100.000 = 50 m. We can set any number, but I suggest the number of contour line follows the rule of thumb as mentioned above. Next, we have to define the number of contour lines.
In the contouring menu, we can choose to create contour line, filled contour or both. Select the point's layer name and the elevation data field. The contour plugin window will appear as in figure 4.ģ. Open the Contour plugin by clicking the icon. Add the points into QGIS map canvas as in figure3.Ģ. Now, let's make contour lines from points dataset with the following steps:ġ.
CONTOUR LINE DEFINITION INSTALL
Check it and Install the plugin if you don't have it in your QGIS 3. You will see the Contour plugin appears as in figure 2. As usual we can get the plugin from Plugins menu > Manage and install plugins. To create contour lines from points, we are using Contour plugin.