This document discusses geospatial data and its presentation in maps. It defines spatial data as data that identifies the geographic location of features on Earth, such as natural or constructed features. Spatial data is usually stored using coordinates and topology and can be accessed and analyzed using Geographic Information Systems (GIS). The document describes the two main types of spatial data - raster and vector - and how they represent real world features differently. It also discusses visualization of spatial data in maps and introduces the software QGIS for geospatial data presentation and mapping.

1. Preparation and Presentation of Geospatial
Data in Maps
AFM Tariqul Islam
Scientific Officer, BARI,Gazipur
E-mail: afmtareq@gmail.com

2. What is Spatial Data?
 Spatial Data –is the data or information that identifies
the geographic location of features and boundaries on
Earth , such as natural or constructed features, oceans ,
and more .
 Spatial data is usually stored as coordinate and
topology, and is data that can be mapped.
 Spatial data is often accessed, manipulated or analyzed
through Geographic Information Systems (GIS)

3. Types of SPATIAL DATA
• RASTER
• VECTOR
• Real World
Source: Defense Mapping School
National Imagery and Mapping Agency

4. Raster and Vector Data Models
Vector Representation
X-AXIS
500
400
300
200
100
600
500
400
300
200
100
Y-AXIS
River
House
600
Trees
Trees
B
B
B B
B
B
B
B G
G
BK
B
B
B
G
G
G G
G
Raster Representation
1 2 3 4 5 6 7 8 9 10
1
2
3
4
5
6
7
8
9
10
Real World
G
G
Source: Defense Mapping School
National Imagery and Mapping Agency

5. Vector Data
Vector data provide a way to represent real world features
within the GIS environment. A vector feature has its shape
represented using geometry. The geometry is made up of one
or more interconnected vertices. A vertex describe a position
in space using an x, y and optionally z axis. In the vector data
model, features on the earth are represented as:
• points
• lines / routes
• polygons / regions
• TINs (triangulated irregular networks)

6. Vector Data
This system of recording features is based on the interaction
between arcs and nodes, represented by points, lines and
polygons. A point is a single node, a line is two nodes with an
arc between them, and a polygon is a closed group of three
or more arcs. With these three elements , it is possible to
record most all necessary information.
Points Lines Polygons

7. Raster Data
Raster Data – cell –based data such as aerial imagery and
digital elevation models. Raster data is characterized by pixel
values. Basically, a raster file is a giant table, where each pixel
is assigned a specific value from 0 to 255. The meaning
behind these values is specified by the user – they can
represent elevations, temperature, hydrology and etc.

8. Visualization of Spatial Data

9. What is GIS ?
• A method to
visualize, manipulate,
analyze, and display spatial
data
• “Smart Maps” linking a
database to the map

12. GIS data formats (files)
• Shapefiles
• Coverages
• TIN (e.g. elevation can be stored as TIN)
– Triangulated Irregular Network
• Grid (e.g. elevation can be stored as Grid)
• Image (e.g. elevation can be stored as image)
Vector data
Raster data

13. A coordinate system used for locating any point on the surface of a sphere or
spheroid is essential for any map projection. It provides scientists with a means
by which they can systematically represent a spatial, surface-based phenomenon
on the Earth's surface onto a flat plane, such as a map.

14. Introducing QGIS
Hands-on-Training
Geospatial Data Presentation
for Mapping

15. 1. Browse Geospatial Data
1.1. Load data
1.2 Browse Geographic Features (shape file/attribute table)
2. Mapping
2.1. Key Options of Geospatial Data Representations
layer order, layer transparency, symbology, label, and annotation.
2.2. Map Layout and Map Components
2.3. Export Maps