Geography Reference
In-Depth Information
4. What is the main difference between discrete and nondiscrete GI?
5. What is the main difference between topological and nontopological
vector data?
6. What is a quad-tree?
7. What is a triangular irregular network (TIN)?
8. How can the GI storage format impact GI representation?
9. How does a buffer operation transform a geographic representation?
10. Why can't maps be transformed?
Answers
1. What sets GI apart from maps in terms of discrete and nondiscrete
information?
GI offers multiple ways to store and transform data that can be used to
make meaningful representations of things and events as GI. Maps can
show both discrete and nondiscrete information, but the information can-
not be transformed.
2. Why are multiple types of data structures needed?
Different types of data structures make it possible to adequately geographi-
cally and cartographically represent observations of things and events.
3. What is Tobler's transformational concept?
Tobler's transformational concept is the development and application of
the mathematical transformation concept to cartography. With this concept
comes an understanding of GI as sets of associations with particular repre-
sentations that can be converted to create other sets of associations.
4. What is the main difference between discrete and nondiscrete GI?
Discrete GI shows things with fixed boundaries; nondiscrete GI shows pro-
cesses or states of processes.
5. What is the main difference between topological and nontopological
vector data?
Topological vector data has a set of relationships between nodes and links;
nontopological vector data maintains only start, possibly intermediate, and
end points.
6. What is a quad-tree?
A quad-tree is a data structure for the efficient storing of raster data follow-
ing a hierarchy based on areas of contiguous attribute values.
7. What is a triangular irregular network (TIN)?
A Tin is a data structure for storing GI based on distance relationships and
single values; it is most widely used for storing and modeling elevation data.
8. How can the geographic data structure impact GI representation?
It allows certain attributes and relationships to be better stored than others;
transformations make it possible to convert GI to other formats that may
resolve the limitations with one particular type of data structure.
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