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GISC9312-Geospatial Visualization

Assignment#D1

Ibeabuchi Nkemakolam

Ogis geoinfo inc. | 13, Wallace street St.Catharines, ON L2S 3A8

April 17, 2013

Janet Finlay BA, .BSc.

GIS-GM Program Professor

Niagara College

135 Taylor Road

Niagara-On-The-Lake, ON

L0S 1J0

Dear Janet

RE: GISC9301 Data Classification

Please accept this letter as my formal submission of Assignment#D1: 3D Analysis in ArcGIS

GISC9312-Geospatial Visualization

This Assignment is aimed at gaining basic familiarity with the techniques of TIN surface

analysis using ArcGIS 3D Analyst Extension.

Ma has been an informative task for me, because it has really exposed me more to the

power of 3D Analyst extension in ArcGIS.

Should you have any regarding the enclosed documents or any technical issues regarding

the files, please contact me through my Email ([email protected]).

Thank you for your time and attention. I look forward to your comment and suggestions.

Please find attached Hard copies of the map and temperature across Canada this letter.

Thank you

Kindest Regards

Ibeabuchi Nkemakolam

Ibeabuchi Nkemakolam.j. GIS (PG)

Enclosure: Map Layout of the Hillshade

mailto:[email protected]


Executive Summary

This assignment focuses on the usage of 3D Analyst extension for the creation and analysis

of three dimensional data using ArcGIS. 3D Analysis is a very powerful means for analyzing

spatial data that have a ‘Z’ component. ‘Z’ can be many things; the most obvious is

elevation, but it can also represent such physical parameters as rainfall depth

(precipitation surface), temperature, even soil pH. ‘Z’ can even represent socio-economic

variables such as population, income and health status

The 3D Analyst extension provides does three primary operations to ArcGIS;

1. Visualize data in 3-D perspective-points, lines, polygon, rasters, images, networks

2. Creates surfaces using various methods

3. Analyze surfaces

The 3D analyst was used to create TINs from the OBM data (spots, contour, and transport);

the TIN was converted to raster data for usability. Slopes and Aspect (degrees and percent)

was also created from this TIN by assigning Z-values to the “center” of each raster cell for

proper output. The range of slopes on the Niagara Escarpment facing the Glendale Campus

was determined. A line of sight was created to determine the visibility from the bluff that

overlooks the Niagara College Glendale Campus. A line of sight was also created to

determine the visibility from the QEW/Glendale Highway interchange berm contrast was

made with the inter-visibility of Niagara College Glendale Campus. A Hillshade surface of

the area of interest was created from the raster data and overlaid on the TIN surface, to

determine the steep areas based on the relative position of the sun at a particular time of

the day. Finally three dimension visualization the surface was created using the Arc scene

extension of 3D Analyst.

Contents Introduction ............................................................................................................................................................................... 1

Background ........................................................................................................................................................................... 1

Goals and Objective ............................................................................................................................................................ 1

Study Area.............................................................................................................................................................................. 1

Slope in Degrees .................................................................................................................................................................. 2

Aspect ........................................................................................................................................................................................... 3

Aspect of Zero degrees ..................................................................................................................................................... 5

Creating in a Line of Sight across the Glendale Campus .......................................................................................... 6

Create a line of sight that proceeds through the QEW/Glendale Highway interchange berm. ............... 7

Conclusion .................................................................................................................................................................................. 9

Bibliography .............................................................................................................................................................................. 9

Figure 1: Slope in degrees and Aspect in degrees ...................................................................................................... 2

Figure 2: Map showing the slope in degrees ................................................................................................................ 3

Figure 3: Graph showing Aspect direction. Courtesy (Esri, 2010)...................................................................... 4

Figure 4 : Map showing the Aspect .................................................................................................................................. 4

Figure 5: Slope range map on the Escarpment ........................................................................................................... 5

Figure 6 : Line of Sight across Niagara College............................................................................................................ 6

Figure 7 : Line of Sight QEW/Glendale Highway interchange berm .................................................................. 7

Figure 8 : Map showing Aspect in degrees ..................................................... Error! Bookmark not defined.

Figure 9: Aspect direction in degrees............................................................... Error! Bookmark not defined.

Figure 10 :Slope range along the Escarpment .............................................. Error! Bookmark not defined.


Introduction

Background

This is brief report on use of 3D Analyst extension tool to perform TIN surface analysis of

OBM data. It is also to query surface data, calculate slope, aspect and visualize the terrain

using hillshading.

Goals and Objective

The aim of this assignment is create and analyze three dimensional data using ArcGIS. It is

also to gain work ability for the application of the surface data queries, TIN, slope, aspect,

hillshade visualization and contour using 3d Analyst extension of ArcGIS.

Study Area

The Study Area for this assignment is the Niagara College Glendale Campus, Niagara

Escarpment and QEW/Glendale Avenue interchange.


Q1: What is the slope (in degrees) and the aspect (also in degrees) of the east facing slope

at the Glendale Avenue interchange of the QEW. Figure 1, below details the location of this

slope:

Slope in Degrees

Slope is the steepness or gradient of a unit of terrain and is measured as an angle in

degrees or as a percentage. Slope is usually measured from an elevation or bathymetric

raster. Essentially slope compares the elevation of points and calculates the maximum rate

of change in value from the cells of the nearest neighbors. It is usually calculated using the

formula “tan (slope) = sqrt (b2 + c2)” .where “b” is the slope in x-direction, c is the slope in

y-direction and z is the height of the elevation.

The Slope (in degrees), of the east facing slope at the QEW Glendale Avenue interchange is

8.072912.The Aspect in degrees of the east facing slope is 102.528809.

Figure 1: Slope in degrees and Aspect in degrees


The deep blue coloration in the map below show areas of high elevation, the green patches

areas shows places of moderate elevation. While the areas milk colors indicates the areas

that are flat without any significant elevation.

Figure 2: Map showing the slope in degrees

Q2: What does aspect mean? What is an aspect of zero degrees?

Aspect

Aspect shows the direction in which a particular terrain is facing. (Esri, 2010) Aspect

identifies the downslope direction of the maximum rate of change in value from each cell to

its neighbors. It can be thought of as the slope direction. The values of each cell in the

output raster indicate the compass direction that the surface faces at that location. It is


usually measured clockwise in degree from 0 (due north) to 360 (again due north), coming

full circle. Flat areas having no downslope direction are given a value of -1.The value of

each cell in an aspect dataset indicates the direction the cell’s slope faces.

Figure 3: Graph showing Aspect direction. Courtesy (Esri, 2010)

Figure 4 : Map showing the Aspect


Aspect of Zero degrees

An aspect of zero degrees slope is used to indicate undefined aspect in flat areas with

slope=0 and is assigned a value of -1.

Q3: What range of slopes is found on the Niagara Escarpment that faces the Glendale

Campus, immediately south of the campus (in percent – include a graphic)?

The range of slopes found along the Niagara Escarpment that faces the Glendale Campus,

immediate south of the campus is between 10 to 76.044205. The range of slopes south the

Escarpment in the diagram below shows that there is a gradual increase in the slope height

along the Escarpment as one move up. And is also a sharp decline in height on the other

part of the Escarpment. The Red colored areas shows steeper areas in the output slope

raster and those areas have higher range slope values. Yellow colored parts have less

slopes range value; those are the parts there is shape decline in range of slope value.

Figure 5: Slope range map on the Escarpment


Q4: create a line of sight that proceeds (approximately) through the Glendale Campus. Why

can the areas that are indicated as not in the line of sight not be seen? Provide a graphic to

support your answer

Creating in a Line of Sight across the Glendale Campus

(Esri, 2010)The line of sight is a graphic line between two points on a surface that shows

where along the line the view is obstructed. The color of the line indicates the locations

where the surface is visible and where it is hidden. The status bar indicates whether the

target is visible or hidden.

The Niagara College Glendale Campus can be seen (visible) atop the bluff from a height of

about 180m elevation before woodend part of the Escarpment. This is clearly indicated by

the green Line (90m distance) before the steep Escarpment. The red line across the steep

escarpment extending to the tip of the Glendale Campus cannot be seen (not visible) at an

elevation of 168m atop the steep Escarpment. This is because those areas that are not

visible have lower elevation level (deep terrain) when compared with the height on

the escarpment.

Figure 6 : Line of Sight across Niagara College


Q5b: Figure 2, above displays a second vantage point. Create a line of sight that proceeds

through the QEW/Glendale Highway interchange berm. Why can the areas that are

indicated as not in the line of sight not be seen? Provide a graphic to support your answer.

Contrast this answer with Question 4.

Create a line of sight that proceeds through the QEW/Glendale Highway

interchange berm. The areas not visible in the line of sight is mainly due to the difference elevation of the

terrain .The QEW/Glendale Highway interchange berm has a higher elevation level (mean

sea level) compared to the elevation of the Glendale Campus area.

Figure 7 : Line of Sight QEW/Glendale Highway interchange berm


The profile graph of the area of shows the difference in elevation (height); i.e. the height of

the escarpment on its eastern part is much higher when compared to the height on the

south. This is why there are contrasting results in the inter-visibility between these two

terrains.

Q6: Create a hillshade analysis for the two OBM tiles you have been working with. The sun

specs should be estimated given the following: March 21st, noon (Eastern Standard

Time).Determine only those areas that experience full shade at this date/time. Provide a

graphic that shows these areas.

Creating Hillshade Analysis for the Area of Interest

The hillshade is a grayscale 3D model of the surface, with the sun's relative position taken

into account for shading the image. This function uses the latitude and azimuth properties

to specify the sun's position. The hillshade was created from the raster data (obtained from

TIN). And set parameters or values were used to obtain the Hillshade of our area of

interest. The azimuth was set at 171.01 degrees and an altitude of 47.01degrees. The

hillshade surface when overlayed on the TIN surface shows the sun’s relation position. The

full shade areas are shaded dark color, where there are no dark patches means there are no

shades in those area.

Figure 8 : Hillshade Analysis of the study area


Conclusion

The ArcGIS 3D Analyst is a powerful tool that can be used to create TIN, slopes, aspect and

visualize terrain using hillshading. And also create a 3D visual representation a terrain for a

more detail analysis.

Bibliography Esri. (2010). ArcGIS 10 Help.

Smith, M. J. (2007). Geospatial Analysis.

www.Esri.com. (n.d.).

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