Surface Analysis in GIS

I
Course Code: URP 3206
Course Title: Geographic Information System (GIS) Lab-2
Report On
Surface Analysis
Date of Submission: 14 August, 2018
Submitted To
Ayesha Siddika
Lecturer,
Department of Urban and Regional Planning
Submitted By
Group - 02
151708 (Rukaiya Taslima)
151717 (Reyada Aktar)
151719 (Afia Akter)
151730 (Ritu Saha)
Session: 2014-15
3
rd
year 2
nd
Semester
Department of Urban and Regional Planning
Pabna University of Science and Technology

II
Abstract
In GIS, the term ‘surface’ refers to a scalar field, a variable represented as a function of
location. A surface represents elevation, temperature distribution, land price, etc. Surface
analysis will depict surface conditions plotted from reported data or generated by computer
models. It plays an important role in the planning of land use. Group-02 area (205 acre) is
covered with 3, 6, 7, 13 and 14 wards of Dhaka City Corporation (DCC) area. This report
focuses on: preparation a map by clipping procedure of study area, Triangulated irregular
network (TIN) model, contour, Surface slope, Raster Digital Elevation Model (DEM), hill
shade maps using 3D - Analyst tool in GIS environment. The analysis has been carried out
for the (group 02 area) of Dhaka state and found that lowest elevation as (7.961-8.704)
from MSL and highest elevation was observed as (14.646-15.389) m with interval of (.743)
m interval each. Surface analysis are used to determine terrain attributes such as elevation
at any point, slope and aspect. Terrain features like drainage basins and channel networks
can also be identified from the maps. These maps are also useful for hydrologic and
geologic analyses, hazard monitoring, natural resources exploration, agricultural
management etc.

III
Acknowledgement
At first, we would like to remember almighty Allah for his blessings & kindness. After
then, we would like to acknowledge the invaluable support and guide of our respectable
course teacher Ayesha Siddika, Lecturer, Department of Urban & Regional Planning,
Pabna University of Science & Technology in completing the report successfully. This
report was made possible by her contributions. Authors would like to extend her
appreciation to her classmates, for their help and contributes to this work.

IV
Table of Contents
Abstract............................................................................................................................... I
Acknowledgement........................................................................................................... III
Chapter One: Introduction........................................................................................... 1-2
1.1 Surface Analysis.........................................................................................................1
1.2 Objectives...................................................................................................................1
1.3 Study Area Profile...................................................................................................1-2
Chapter Two: Methodology........................................................................................ 3-14
2.1 Working Procedure ....................................................................................................3
2.2 Selection of Study Area According to Group Number ..............................................4
2.3 Shape File Clipping Procedure...................................................................................4
2.4 Digital Elevation Model (DEM) ................................................................................6
2.4 Triangulated Irregular Network (TIN).......................................................................6
2.5 Contour map...............................................................................................................8
2.6 Raster DEM, Zonal Statistics and Histogram ............................................................9
2.6.1 Raster DEM .........................................................................................................9
2.6.2 Zonal Statistics ....................................................................................................9
2.6.3 Histogram ..........................................................................................................11
2.7 Hillshade Map ..........................................................................................................12
2.8 Slope Map ................................................................................................................13
2.9 Profile Graph............................................................................................................14
Chapter Three: Conclusion.............................................................................................16
References.........................................................................................................................16

V
List of Maps
Map’s name Page No.
Map of Study Area 9
Triangulated Irregular Network (TIN) Model 11
Contour Map of Study Area 12
Raster DEM of Study Area 13
Histogram of Raster DEM of Study Area 15
Hillshade Map of Study Area 16
Surface Slope Map of Study Area 18
Profile Graph of Study Area 19
List of Tables
Table name Page No.
Table-01: Area covered by the wards of study area 6
Table 02: Total area, highest, lowest and average elevation of study area 14

1
Chapter One: Introduction
Geographic Information System (GIS) is a computer based application of technology
involving spatial and attributes information to act as a decision support tool. In a general
sense, the term describes any information system that integrates stores, edits, analyzes,
shares, and displays geographic information. Arc GIS is typically used to represent maps
as data layers that can be studied and used to perform analysis. GIS provides, for every
kind of location based organization, a platform to update geographical data without wasting
time to visit the field and update a database manually.
1.1 Surface Analysis
A surface is a vector or raster dataset that contains an attribute value for every locale
throughout its extent. In a sense, all raster datasets are surfaces, but not all vector datasets
are surfaces. Surfaces are commonly used in a geographic information system (GIS) to
visualize phenomena such as elevation, temperature, slope, rainfall, and more.
Surface analysis will depict surface conditions plotted from reported data or generated by
computer models. Surface analyst in GIS generated the contour, slope, aspect, and hill
shade maps. 3D Analyst in GIS environment can create new surfaces from existing data
sets. For many applications, need to create a surface in order to draw other features over it.
These surfaces as regularly spaced grids or as triangulated irregular networks (TINs).Once
the surface data has been created it can be used for further analysis including enhanced
visualization, such as creating a shaded relief, or for more advanced analysis such as
determining the visibility from a specific position or route. Available surface analysis tools
include hill shade, slope, aspect, curvature, cut fill, view shed, line of sight, surface length,
surface spot, surface volume, interpolate shape, slice etc.
1.2 Objectives
 To generate contour map, slope map, aspect map and hillshade map using 3D - Analyst
tool in GIS environment.
 To identify the highest, lowest and average elevation of our study area and
 To show the variation in elevation for the selected section that fulfills the criteria given
in the problem.
1.3 Study Area Profile
Group-02 area is the central part of Dhaka City and it includes most of the parts of Dhaka
City Corporation (DCC) area. Dhaka City Corporation (DCC) was the former self-
governing corporation that was entrusted with the task of running the municipal affairs of
Dhaka city. The incorporated area was divided into several wards. The latitude and
longitude of the area is 23°43'N and 90°26'E respectively.

2
This report contains the surface analysis of the 2nd segment of the study area. The total
area of the 2nd
segment study area is 829699 Square meter or 205 acre. It contains with 3,
6, 7, 13 and 14 ward of Dhaka City Corporation.
Table-01: Area covered by the wards of study area
Source: br.lgd.gov.bd
Ward Area
3 MIRPUR SEC-11(BLOCK-C)(PART-1)
MIRPUR SEC-11(BLOCK-C)(PART-2)
MIRPUR SEC-10 (BLOCK-A)
MIRPUR SEC-10 (BLOCK-B)
MIRPUR SEC-10 (BLOCK-C)
MIRPUR SEC-10 (BLOCK-D)
6 DOARI PARA
EASTERN HOUSING
MIRPUR SEC-6 (BLOCK-TA/E)
MIRPUR SEC-6 (BLOCK-JA)
MIRPUR SEC-6 (BLOCK-JHA)
7 MIRPUR SEC-2(BLOCK-F)
MIRPUR SEC-6 (BLOCK-B)
MIRPUR SEC-2 (BLOCK-H)
MIRPUR SEC-2 (BLOCK-CHA)
ALOBDI
RUPNAGAR
SHIALBARI
RUPALI HOUSING ESTATE
13 BARABAGH
MANIPUR(PART-1)
MANIPUR(PART-2)
MANIPUR(PART-3)
PIRERBAGH (PART-1)
PIRERBAGH (PART-2)
14 PURBA KAZIPARA
PURBA SENPARA PARBATA
PURBA SHEWRA PARA
PASCHIM SHEWRAPARA (PART-1)
PASCHIM SHEWRAPARA (PART-2)
PASCHIM KAZI PARA

3
Chapter Two: Methodology
2.1 Working Procedure: The following steps are followed to find the solution-
Step 13: Preparation a profile graph and showing the great variation among the
elevation data of the study area.
Step 12: Finding the highest, lowest and average elevation of the study area
Step 11: Preparation of Hillshade map for the study area using raster DEM
Step 10: Conversion of TIN to raster DEM using 3 m as cell size and classification
of DEM into 10 classes.
Step 9: Showing variation in elevation for a selected section of study area with
suitable profile graph
Step 08: Creation of Slope map for the study area from TIN which will be
measured in degree
Step 07: Creation of contour map from TIN with one feet interval
Step 06: Creation of DEM (Tin or raster DEM)
Step 05: Clipping the shapefiles for the selected area
Step 04: Building query by Using Definition Query
Step 03: Selection of area by attributes relevant to Student ID
Step 02: Adding shapefiles to Arc Map
Step 01: Folder connection in Arc Catalog

4
2.2 Selection of Study Area According to Group Number
2.3 Shape File Clipping Procedure
The same procedure is applicable for other shape files such as Ward_bnd, road_pline.
Click on Ok
Selection of 'Id=2"
Query Builder
Select on "Definition query"
Selection of properties of "Study_Area_02"
Selection of"This layer's spot data" & ok
Export Data-click on Output feature class and save this shapefile by named
"Study_Area_02"
Click on Data
Right click on Study_Area
Apply and ok
Layer: Study_area and Select "Id"= 2
Click on Selection by Attributes
Go to the "Selection" from Menu bar
Apply and Ok
Output Spot_02
Clip: Study_Area_02
Input: Spot_height
Selection of "Clip"
Geoprocessing
Selection of Shapefile

6
2.4 Digital Elevation Model (DEM)
A Digital Elevation Model (DEM) is a specialized database that represents the relief of a
surface between points of known elevation. By interpolating known elevation data from
sources such as ground surveys and photogrammetric data capture, a rectangular digital
elevation model grid can be created (Balasubramanian, 2017). DEMs are used to determine
terrain attributes such as elevation at any point, slope and aspect.
Terrain features like drainage basins and channel networks can also be identified from the
DEM. DEMs are widely used in hydrologic and geologic analyses, hazard monitoring,
natural resources exploration, agricultural management etc. Hydrologic applications of the
DEM include groundwater modeling, estimation of the volume of proposed reservoirs,
determining landslide probability, flood prone area mapping etc.
Two main type of structures used are the following:
a) Triangulated irregular networks (TIN)
b) Contours.
c) Regular square grids or raster cells
At first, this report is showed the methodological steps of TIN. It is used in mapping and
analysis is that the points of a TIN are distributed variably based on an algorithm that
determines which points are most necessary to an accurate representation of the terrain.
This is an advantage of using a TIN over a raster DEM.
2.4 Triangulated Irregular Network (TIN)
A triangulated irregular network (TIN) is a vector-based representation of a surface.
Although TINs are commonly used in applications that involve terrain, they can also be
used for representing other variables that can be conceptualized as surfaces. TINs are
composed of a series of contiguous, non-overlapping triangles that are known as faces.
They are built from a series of points using a technique called Delaunay triangulation, in
which a network that connects each point to its nearest neighbors is built to form the
triangular faces. TINs have some advantages over raster-based representations of surfaces
in that they are much more efficient at storing data because the resolution of the
representation can be matched to the scale of variability present in the surface by including
more or fewer points.

7
Methodological Steps:
Interpretation and Uses:
A TIN used to represent terrain is often called a digital elevation model (DEM), which can
be further used to produce digital surface models (DSM) or digital terrain models (DTM).
An advantage of using a TIN over a rasterized digital elevation model (DEM) in mapping
and analysis is that the points of a TIN are distributed variably based on an algorithm that
determines which points are most necessary to create an accurate representation of the
terrain. TINs are a form of vector-based digital geographic data and are constructed by
triangulating a set of vertices. The vertices are connected with a series of edges to form a
network of triangles. It shows the elevation of SPOT data of the overall area. The above
map shows that the highest elevation ranges from 14.648m to 15.389m and the lowest range
is 7.961m to 8.704m.
Classify into 10 classes and apply ok
Selection of Symbology
Selection of properties of tin
Click on ok
Select Height Field: RL and Tag Field:
RL
Spatial Reference: Import point features
Input feature class: Spot_02
Output TIN: TIN
Selection of "Create TIN"
Click on TIN
Selection of Data Management
Selection of 3D Analyst tool
ArcToolbox

8
2.5 Contour map
Contours are sets of lines of equal value across a surface. They are frequently created to
represent surfaces on a map. A topographic map on which the shape of the land surface is
shown by contour lines, the relative spacing of the lines indicating the relative slope of the
surface. A map that shows elevations above sea level and surface features of the land by
means of contour lines.
Contour interval: The contour interval of a contour map is the difference in elevation
between successive contour lines.
Interpretation and Uses
From the contour line, user can identify which locations have the same value. By looking
at the spacing of adjacent contours, user can gain a general impression of the gradation of
values. The areas where the contours are closer together indicate the steeper locations. In
the map that the highest elevation of the study area is about 15m and the lowest is 8m. This
map to show elevations and surface configuration by means of contour lines. Contours are
Selection of properties of Contour to
on the lable features
Click on ok
Input Surface: TIN ; OutPut Feature
Class: Surface_contour ; Contour
Interval: 0.3048m
Selection of "Create TIN"
Selection of "Surface Contour"
Selection of Triangulated Surface
ArcToolbox

9
one of several common methods used to denote depth on maps. From these contours, a
sense of the general terrain can be determined.
2.6 Raster DEM, Zonal Statistics and Histogram
2.6.1 Raster DEM
Surfaces are usually modeled with raster datasets. By interpolating known elevation data
from sources such as ground surveys and photogrammetric data capture, a rectangular
digital elevation model grid can be created. A Digital Elevation Model (DEM) can be
represented as a raster or a grid of squares, also known as a height map. The Triangulated
Irregular Network (TIN) DEM dataset is also referred to as a primary DEM, whereas the
Raster DEM is referred to as a secondary DEM.
2.6.2 Zonal Statistics
Zonal Statistics is a statistic tool which is calculated for each zone defined by a zone dataset,
based on values from another dataset (a value raster). A single output value is computed
for every zone in the input zone dataset.
The Zonal Statistics as Table tool calculates all, a subset or a single statistic that is valid for
the specific input but returns the result as a table instead of an output raster.
A zone is all the cells in a raster that have the same value, whether or not they are
contiguous. The input zone layer defines the shape, values, and locations of the zones. An
integer field in the zone input is specified to define the zones. A string field can also be
Click on ok
Input point Feature: Spot_02 ; Z
value Field: RL ; Output Raster:
GRID: Output cell size: 3.576
Selection of "Natural Neighbor"
Selection of Raster Interpolation
ArcToolbox

10
used. Both raster and feature datasets can be used as the zone dataset. The input value raster
contains the input values used in calculating the output statistic for each zone.
Table 02: Total area, highest, lowest and average elevation of study area
The highest elevation of the area is 15.184182 and the lowest elevation is 7.96287. The
mean elevation is 11.231348. So deviation of elevation data from the mean is no so large.
This statistics will help to describe data, to add validity to the research, and to make sound
decisions. Traditionally, statistics are used on a random but representative subset and the
results are extrapolated to the larger group. Inferential statistics, however, don't always
work as well with geographic data. When this is the case, descriptive statistics are applied.
ID Count Area Highest
Elevation
Lowest
Elevation
Average
Elevation
2 63961 818274.42 15.184182 7.96287 11.231348
Statistics Type: Min,Max & Mean and than Click
on Apply & ok
Output Table Zone : Histogram
Input Value Raster: Grid
Zone field:Id
Input raster or feature zone data:Study_area_02
Click on Zonal Statistics as table
Click on Zonal
Go to Menubar & click on ArcToolbox

11
2.6.3 Histogram
A histogram is an accurate representation of the distribution of numerical data. It is an
estimate of the probability distribution of a continuous variable. Histograms give a rough
sense of the density of the underlying distribution of the data, and often for density
estimation: estimating the probability density function of the underlying variable. The total
area of a histogram used for probability density is always normalized to 1. If the length of
the intervals on the x-axis are all 1, then a histogram is identical to a relative frequency plot.
A zonal histogram is a graph that shows a series of histograms for each unique zone. The
zones are used to specify which cells in Value input are used to create the histograms. A
field from the Zone input can determine the zones. The Value cells that intersect or are
contained within each zone are used to generate a spate histogram for each the zones.
Output graph name: Histogram &
click on ok
Zone field:FID; Input Value Raster:
Grid; Output table: Histogram
Input raster or feature zone
data:Study_area_02
Selection of Zonal Histogram
Click on Zonal
Selection of Spatial Analyst tools
Go to Geoprocessing from Menubar
& click on ArcToolbox

12
The x-axis of the histogram is the range of the available digital numbers, i.e. 0 to 255. The
y-axis is the number of pixels in the image having a given digital number. In the above map
7.96m-8.68m range has the highest no of grids and the range 14.46m-15.18m contains the
lowest number of grids. If the zone input is a raster with no attributes, the Value field of
the raster is used. Otherwise, integer or character fields in the input raster can be used to
define the zones. If there is a selection on the zone input, then only selected features are
used to specify cells.
2.7 Hillshade Map
A hill shade is a grayscale 3D representation of the surface, with the sun's relative position
taken into account for shading the image (Giridhar, 2007). It does this by setting a position
for a hypothetical light source and calculating the illumination values of each cell in relation
to neighboring cells. It can greatly enhance the visualization of a surface for analysis or
graphical display, especially when using transparency. By default, shadow and light are
shades of gray associated with integers from 0 to 255.
Right click on Hillshade Properties;
Display & transparency 25% and
Then ok.
Model shadow properties have to
"On"Click on ok
Input Raster: GRID ; Output::
Hillshade
Selection of Raster Surface
ArcToolbox

13
Interpretation and Uses:
 The hill shade tool creates a shaded relief raster from a raster. The illumination source
is considered to be at infinity.
 The hill shade raster has an integer value range of 0 to 255.
 Two types of shaded relief raster’s can be output. If the Model shadows option is
disabled, the output raster only considers local illumination angle. If it is enabled, the
output raster considers the effects of both local illumination angle and shadow.
 The analysis of shadows is done by considering the effects of the local horizon at each
cell. Raster cells in shadow are assigned a value of zero.
 To create a raster of the shadow areas only, use the Reclassify tool to separate the value
zero from the other hill shade values. The Model shadows option must be enabled to
create this result.
 If the input raster is in a spherical coordinate system, such as decimal degrees, the
resulting hill shade may look peculiar. This is due to the difference in measure between
the horizontal ground units and the elevation z units.
 When the input raster needs to be resampled, the bilinear technique will be used.
2.8 Slope Map
A slope map indicating the topography of an area along with an analysis of s features as
they have influenced and may continue to influence land development. Slope is the measure
of steepness or the degree of inclination of a feature relative to the horizontal plane. Slope
is typically expressed as a percentage, an angle, or a ratio. It is calculated for each triangle
in TINs and for each cell in raster’s.
Click on Ok
Go to the Multiple Attributes; Give a value Fields: (slope
code)
Selection of Slope properties and then click symbology
Click on Ok
Input Feature: TIN
Output Feature Class: SurfaceSlope; Slope Units: Degree
Selection of Surface slope
ArcToolbox

14
The average slope of a terrain feature
can conveniently be calculated from
contour lines on a topographic map.
To find the slope of a feature, the
horizontal distance (run) as well as the
vertical distance (rise) between two
points on a line parallel to the feature
need to be determined. The slope is
obtained by dividing the rise over run.
Multiply this ratio by 100 to express
slope as a percentage.
The slope angle expressed in degrees
is found by taking the arctangent of
the ratio between rise and run. This
colorized slope is appropriate for
visualizing the orientation of the
terrain at a large map scales.
2.9 Profile Graph
Profile shows the change in elevation of a surface along a line. Profile graphs allow to
visualize elevation change over a continuous distance using 3D line geometry. Visualizing
elevation change with a profile graph allows for the elevation change to be displayed
simultaneously for multiple 3D line features. Profile graph tools on the 3D analyst
interactive toolbar are used to derive a graphic representation of one or many profiles.
Profiles can be generated from any 3D line feature drawn over a surface. Profile creates on
either a raster, Triangulated Irregular Network (TIN) or terrain dataset surface.
The following list provide examples for generating profile graphs from various analysis
results:
 Digitizing a 3D line from a surface using the Interpolate Line interactive tool.
 3D line features from a line feature class.
 Line of Sight visibility analysis results from using the Line of Sight interactive tool.
 Steepest path surface analysis results from the Steepest Path interactive tool.
 Digitizing a 3D line across a multipoint or point feature class.

15
The example below depicts a profile graph that displays elevation change over the length
of the input 3D lines.
 X-Axis—Horizontal distance
 Y-Axis—Elevation
A profile graph can be created from:
 3D line graphics (created with the Steepest path and Line of Sight tools)
 3D polyline features (for example, geo database feature class and shapefile)
Profile graphs consist of continuous
horizontal distance on the x-axis and
elevation on the y-axis. The horizontal
distance refers to the distance from the
beginning of each 3D line when projected
onto an imaginary horizontal plane,
measured along the line. This applies
whether or not all vertices are collinear in
this horizontal projection. The profile
graph displays the elevation and speed
profile of all positions in a graph below the
map and the position list. When the profile
graph is first created, its unit of measure is
set to that of the dataset, defaulting to
meters if a unit is not found.
Right Click on Graph and selection of Add
to Layout
Create Profile Graph
Draw a Interpolate Line
Selection of 3D Analyst toolbox
Select Customise from Menubar

16
Chapter Three: Conclusion
A surface is a vector or raster dataset that contains an attribute value for every locale
throughout its extent. In a sense, all raster datasets are surfaces, but not all vector datasets
are surfaces. Surfaces are commonly used in a geographic information system (GIS) to
visualize phenomena such as elevation, temperature, slope, aspect, rainfall, and more.
Surface analyst in GIS generated the contour, slope, aspect, and hill shade maps. 3D
Analyst in GIS environment can create new surfaces from existing data sets. This
topographic features represent the surface condition of the study area. These maps are used
to determine terrain attributes such as elevation at any point, slope and aspect. Terrain
features like drainage basins and channel networks can also be identified from the maps.
These maps can be used in hydrologic and geologic analyses, hazard monitoring, natural
resources exploration, agricultural management etc.
References
Anonymous (n.d.) “How Zonal Statistics works”, URL: http://desktop.arcgis.com
/en/arcmap/10.3/tools/spatial-analyst-toolbox/h-how-zonal-statistics-works.htm.
Anonymous (n.d.) “DHAKA NORTH CITY CORPORATION”, URL: br.lgd.gov.bd/files/
Dhaka%20North%20City%20Corporatation.doc.
Anonymous (n.d.) “Zonal Histogram”, URL: http://desktop.arcgis.com/en/arcmap/
10.3/tools/spatial-analyst-toolbox/zonal-histogram.htm
Balasubramanian A. (2017) “DIGITAL ELEVATION MODEL (DEM) IN GIS” Report
No. 3, DOI: 10.13140/RG.2.2.23976.47369, University of Mysore, Karnataka, India.
Giridhar, M.V.S.S. and Viswanadh, G.K. (2007) “SURFACE ANALYSIS USING GIS”
paper presented at the National Conference on Soft Computing Applications in Water
Resources & Environmental Engineering, December 2007.
Siddika A. (n.d.) “Surface Analysis” an unpublished report, Department of Urban &
Regional Planning, Bangladesh University of Engineering & Technology (BUET), Dhaka.
Wikipedia (2018) “Contour line”, URL: https://en.wikipedia.org/wiki/Contour_line
accessed on 26 September, 2018.
Wikipedia (2018) “Histogram”, URL: https://en.wikipedia.org/wiki/Histogram accessed
on 10 September, 2018.

Surface Analysis in GIS

Empfohlen

Empfohlen

Weitere ähnliche Inhalte

Was ist angesagt?

Was ist angesagt? (20)

Ähnlich wie Surface Analysis in GIS

Ähnlich wie Surface Analysis in GIS (20)

Mehr von RituSaha3

Mehr von RituSaha3 (15)

Kürzlich hochgeladen

Kürzlich hochgeladen (20)

Surface Analysis in GIS