abstract (virtual).
- Existing in reality geographical objects, phenomena and events can be perceived
either directly through senses or indirectly with devices’ usage.
-
Virtual objects may not exist in reality but still be displayed. They include
objects existing in the past, or which presence is foreseen in the future and imaginary.
Imaginary objects are boundaries, horizontals, projected buildings etc.
Spatial analysis is related to the search for the area structure on the map. In visual
analysis of the map such tasks are solved as: image recognition, object identification;
assessment of relative location of the objects; assessment of objects distribution;
determining spatial relations of objects; identification of trends; assessment of terrain
in real time, at different scales, in different size of space; quick information processing.
Traditional maps – are flat (two-dimensional – 2D) models of the real world. 2D
visualization is performed for them. Visualization is transmitted through symbols as
separate objects and as objects’ groups. The symbols are formed by markers, lines, fill,
color and text. In GIS the possibilities of cartographic visualization are determined by
powerful arsenal of graphic output tools which support hatching, fill, texture, color,
priorities, transparency, visibility, masking etc. Color is one of fundamental properties
of symbols and map elements. Working with maps requires the presence of knowledge
about map’s symbols. Symbols are the language of maps. Knowing them, one can learn
to read the map, imagine and evaluate the terrain’s character and landscape with their
help. The value of each symbol used in the map is described in the legend of the map.
The legend of the map connects attributes with geographical objects. It is the key to
identify objects that are depicted at the map. Three-dimensional visualization imitates
spatial reality. 3D visualization helps the reader to naturally perceive three-dimensional
model of the earth’s space, often without any special preparation or knowledge of the
legend. It ensures that intuitive understanding which cannot be achieved by considering
conventional two-dimensional image. 3D visualization allows physically imagine a
part of the earth's ’pace and evaluate it. 3D visualization allows faster recognize images
and understand changes in ordinates. Creation of 3D realistic schemes requires
considerable increase in resources. However, the practice of recent years witnesses
that the demand for 3D model grows fast. There is a steady shift from traditional 2D
GIS to 3D GIS. 3D models of the earth’s space become more meaningful. The most
common examples are three-dimensional urban models. Geographical objects of the
real world are depicted by quantitative and qualitative data. That’s why in many cases
the knowledge of the geographical structure of only one category set of objects is not
sufficient. The most complete representation of objects includes also their quantitative
data. Studying the geographical structure of quantitative data is one of the aspects of
location analysis. Analysis of quantitative data location allows to compare objects
based on their quantitative characteristics, determining locations that meet the specified
- 281 -