Isolines are curves that unite surface points having same quota value.
Quota value meaning depends on surface physical magnitude intended to model. Thus a surface that represents temperature it is obtained isothermal; to atmospheric forecast, isobaric; terrain height, level curves, etc.
Source: (SPRING 5.3, 2012).
Isolines can be viewed like a plane projection (x,y) of intersections between the surface and equidistant horizontal planes.The isovalue curves have some important properties among them: all are closed unless they intercept map definition border, and never cross each other.
TerraAmazon generates isoline or isovalue curves from the terrain numeric model in a rectangle and triangle grid format using a cell method.
In this method, for each cell is generated all isovalue curves that intercept this cell. The line segments are stored, in a final phase, to be linked making an isovalue closed curve (in case they do not touch the interest region border).
Select PROCESSING → DTM PROCESSING → CREATE ISOLINES in the main menu.
Layer Name: select a layer that will be used to generate isolines. Be sure that there is a rectangle grid (Grid) or a triangle grid (TIN) representation
Dummy Value: check in this box to enter the pixel dummy value. This dummy value will be ignored by the operation to crate the isolines.
Step: check Fixed option if isolines will be distributed equally in equal quote intervals. Change the Vmin and Vmax values if wanted. Initially, these fields have default values. Also, enter a step value between isolines.
If Variable option is selected enter the wanted quote value for isoline. Click on the right arrow to insert in the value list. Repeat the procedure until insert all the quote values. To remove a value, click on it and on the left arrow. To remove all click on “all” left arrow.
Create guidelines: when fixed step is selected, each line in five steps interval will be considered and created as a guideline. It will not be showed in a different line style or width in the picture but indicated only in line attributes.
Repository:
Click on the icon
to save the result in a shape file or click on the icon
to save it in a data source.
Layer Name: enter a name for the output layer.
Click on the OK button.