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6.6.1 Digital Field Modelling and Possible 3D Views
Digital terrain modelling aims to form a mathematical model that will faithfully
represent the surface of the terrain and enable various analyses and applications (de
Smith et al. 2009). In order for these analyses to be performed efficiently, bearing in
mind that 3D models usually consist of a large amount of data, special organization
and standardization of data is required. In essence, the process of forming a 3D
model consists of selecting and implementing a data structure and an appropriate
creation method. The surface of the terrain is usually represented by a set of points
and lines arranged on the surface of the terrain in an appropriate manner and
arranged in the necessary structure for easier handling of this data. Also, an integral
part of the 3D model are the methods by which, in addition to the given data structure, the topographic surface is defined in the geometric and geomorphological
sense. In general, the surface of the terrain can be presented in three ways, as
follows:
• Isohypses
• Through the functions of two variables
• Volumetric (volume) model
The first way, i.e. the representation of the terrain with isohypses, is the cross
section of the terrain surface and horizontal planes placed at appropriate heights.
This section is a curved line that we call isohypses. This is the most commonly used
way when it comes to presenting terrain on the cartographic bases. This way of
presenting the terrain surface is characterized by high quality in the geomorphological sense, because all the important relief characteristics of the terrain are included
in this way. Also, when the terrain is mathematically represented by isohypses in
digital form, the surface of the terrain is not given explicitly, but it is given implicitly
over the cross section of that surface with horizontal planes. That’s why this way
modelling the terrain surface is not an exact enough method, because the question
arises as to what happens to the values of the terrain height between two adjacent
isohypses. This dilemma is especially pronounced in places where characteristic
relief forms appear, such as peaks, bottoms, watersheds, watersheds, valleys, etc.
Another way to represent the terrain surface in digital form is to use the function
of two variables, where those variables belong to the corresponding domain. Most
often, these are functions in which a unique location value is obtained for a given
location (usually planimetric coordinates x and y of the local coordinate system,
state coordinate system or even geographical coordinates). In this case, it is a 2.5D
(2D + 1D) model.
Terrain models that enable the representation of surfaces where one height can
be obtained for one x, y location, i.e. surfaces for which the surface function f (x, y)
has a value in the form of a vector, are called 3D models. In these models, all three
coordinates are completely equal. The most well-known and in practice the most
common 3D terrain models based on these principles are digital terrain models
6 Evidence for Atmospheric Depositions Using Attic Dust, Spatial Mapping…
6.6.1 Digital Field Modelling and Possible 3D Views
Digital terrain modelling aims to form a mathematical model that will faithfully
represent the surface of the terrain and enable various analyses and applications (de
Smith et al. 2009). In order for these analyses to be performed efficiently, bearing in
mind that 3D models usually consist of a large amount of data, special organization
and standardization of data is required. In essence, the process of forming a 3D
model consists of selecting and implementing a data structure and an appropriate
creation method. The surface of the terrain is usually represented by a set of points
and lines arranged on the surface of the terrain in an appropriate manner and
arranged in the necessary structure for easier handling of this data. Also, an integral
part of the 3D model are the methods by which, in addition to the given data structure, the topographic surface is defined in the geometric and geomorphological
sense. In general, the surface of the terrain can be presented in three ways, as
follows:
• Isohypses
• Through the functions of two variables
• Volumetric (volume) model
The first way, i.e. the representation of the terrain with isohypses, is the cross
section of the terrain surface and horizontal planes placed at appropriate heights.
This section is a curved line that we call isohypses. This is the most commonly used
way when it comes to presenting terrain on the cartographic bases. This way of
presenting the terrain surface is characterized by high quality in the geomorphological sense, because all the important relief characteristics of the terrain are included
in this way. Also, when the terrain is mathematically represented by isohypses in
digital form, the surface of the terrain is not given explicitly, but it is given implicitly
over the cross section of that surface with horizontal planes. That’s why this way
modelling the terrain surface is not an exact enough method, because the question
arises as to what happens to the values of the terrain height between two adjacent
isohypses. This dilemma is especially pronounced in places where characteristic
relief forms appear, such as peaks, bottoms, watersheds, watersheds, valleys, etc.
Another way to represent the terrain surface in digital form is to use the function
of two variables, where those variables belong to the corresponding domain. Most
often, these are functions in which a unique location value is obtained for a given
location (usually planimetric coordinates x and y of the local coordinate system,
state coordinate system or even geographical coordinates). In this case, it is a 2.5D
(2D + 1D) model.
Terrain models that enable the representation of surfaces where one height can
be obtained for one x, y location, i.e. surfaces for which the surface function f (x, y)
has a value in the form of a vector, are called 3D models. In these models, all three
coordinates are completely equal. The most well-known and in practice the most
common 3D terrain models based on these principles are digital terrain models
6 Evidence for Atmospheric Depositions Using Attic Dust, Spatial Mapping…