All about remote sensing

1. Concept of Data Models
BY
Adeyemi Bamidele Ezekiel

2. Data Models
• Data models are a way of organizing any object, area
and/or phenomena that we wish to study in all levels.
• The models provide a way of visualizing and
researching about the world in an organized and
structured way in a digital domain.
• Two types of data are used in GIS platform; that is,
spatial data and non-spatial data.

3. Spatial data and Non spatial data
•Spatial data are those that have coordinates;
latitudinal and longitudinal that shows position
of feature.
•Non spatial data are those representing a set of
information that is systematically organized and
computing against each spatial data. These types
are also known as attribute data.

4. Spatial Data And Non-spatial Data

5. Types of Spatial Data
• The spatial data are further divided into two types; Raster data
and Vector data.
• The raster data are the data that have individual pixels where
each pixel has its spatial location in referenced to real earth.
• The area is covered by grid with (usually) equal-sized cells,
extents in rows and columns
• Vector data, the spatial information are recorded as x, y
coordinates.
• Vector Data are in the form of point, line and polygon that are
recorded in spatial information as x and y coordination.

6. Data model

7. Raster Data structure: The area is covered by grid with (usually)
equal-sized cells, extents in rows and columns

8. Vector data structure: Vector Data are in the form of point, line
and polygon that are recorded in spatial information as x and y
coordination.

9. TIN (Triangulated Irregular Network surface):This feature is a vector
data structure representing the earth surface as contiguous non
overlapping triangles where within each triangle the surface is read
by a plane.

10. • Some of the important raster file formats are;
• Image Image File World File
• TIFF image.tif image.tfw
• Bitmap image.bmp image.bpw
• BIL image.bil image.blw
• JPEG image.jpg image.jpw
• There are two types of file formats in vector data structure; Shapefile
and Geodatabase.
File formats Raster and Vector:

11. Advantages of Raster Data Structures:
• It is Simple data structures
• It overlay and combination of maps and remote sensed
images
• The spatial analysis methods is simple to perform
• The technology is both manual and digital

12. Disadvantages of Raster Data Structures:
• The raster maps are considerably less beautiful than line
maps
• Network linkages are difficult to establish
• Projection transformations are time consuming unless
special algorithms or hardware is used.

13. Advantages of Vector Data Structures:
• The representation is good
• Topology can be completely described
• Retrieval, updating and generalization of graphics and
attributes is possible

14. Disadvantages of Vector Data Structures:
• It is a complex Data Structures
• Also combination of several vector polygon maps through overlay creates
difficulties
• Display and plotting can be expensive, particularly for high quality color
• The technology is expensive, particularly for the more sophisticated
software and hardware