1. Introduction to Geography
First lecture 2-hr

4. Earth surface
• The true surface of the earth is a geoid it is
not uniform at all points, because the
direction of gravity changes, therefor, the
shape of the geoid is irregular.
• To simplify the model, various spheroids have
been used to model the surface of the earth.
• One particular spheroid is distinguished from
another by the lengths of the semi-major and
semi-minor axes.
• Examples Clarke 1866 , GRS 1980 , WGS 1984

5. • Geographic coordinate system is
– 3D coordinate system
– based on earth surface
– Uses angular units of measurements
– Needs a prim meridian
– Needs datum
– While a spheroid approximates the shape of the earth, a
datum defines the position of the spheroid relative to
the center of the earth.

11. • Any point on the earth surface can presented by
two coordinates from a geographic coordinate
system.

12. Projected coordinate system
• A projected coordinate system is defined on a
flat, two-dimensional surface. Unlike a
geographic coordinate system, a projected
coordinate system has constant lengths,
angles, and areas across the two dimensions.
A projected coordinate system is always based
on a geographic coordinate system that is
based on a sphere or spheroid.

14. Natural projections

18. • When the earth surface is projected it will be
distorted, there are two major types of distortion
aerial, and angular distortion and the map can
have one of them but any map will have scale
distortion, this distortion will be less on the map
center, for instance the tangent lines, tangent
points, and the secants of the projections

19. GIS and Data models
• GIS has many definitions one can defined it by
its purpose.
• The Study, the analysis of maps, which will be
changeable in easy manner and any
information can be extracted from the proper
data; this can be done using GIS.
• a group of geographic maps that has a
spatial reference or it has the ability to feel it’s
position with the respect to specific datum
and feels the elements which contains.

20. • A group of spatial objects the contain
information about every object and can be
incorporated in any analysis operation.
• therefore, Any geographic information system
must contain.
– Data.
– Analysis media.
– Analysis operations and procedures.
– Analysis outputs and visualizations.
– And the most important element is the analyst.
GIS and Data models

21. ArcGIS Data
• In order to organize data with a consistent
system the data are divided into layers.
• Every layer mostly can contain one data type
• ArcGis data types are divided into two mane
categories:
– Features
• Points
• Polygons
• polyLines
– Surfaces ”raster”

22. • The features are linked to attribute tables”
tabular data” at which every entity
represented by a row and ever attribute is
represented by a column.
• The raster is represented by the pixel value.
ArcGIS Data

30. • GIS Have three basic roles that is
– Connectivity
– Proximity
– overlay

38. connectivity

39. proximity

40. overlay

42. ArcMap
• ArcMap is the main application used in ArcGIS
for Desktop for mapping, editing, analysis, and
data management. ArcMap is used for all 2D
mapping work and visualization.

44. ArcGlobe
• ArcGlobe is used for 3D visualization of
geographic data using a continuous global
view. This application is generally designed to
be used with very large datasets that are
displayed using varying levels of detail.
ArcGlobe is part of the optional ArcGIS 3D
Analyst extension

46. ArcScene
• ArcScene is used for 3D visualization of
focused scenes or areas. It creates a 3D scene
view that you can navigate and interact with
for enclosed areas of interest. ArcScene is also
part of the ArcGIS 3D Analyst extension.

48. ArcCatalog
• The ArcCatalog application provides a catalog
window that is used to organize and manage
various types of geographic information for
ArcGIS for Desktop