GISC9312- Geospatial Visualization

Transcription

1 GISC9312- Geospatial Visualization Assignment#D1 Ibeabuchi Nkemakolam

2 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 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

3 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.

4 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 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.

5 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.

6 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 The Aspect in degrees of the east facing slope is Figure 1: Slope in degrees and Aspect in degrees

7 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

8 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

9 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 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

10 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

11 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

12 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 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

13 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. (n.d.).