Lab 4: Raster and Terrain Data Manipulation

GEOG 4/575 Lab 4: Raster and Terrain Data Manipulation

Due Oct 29 in class.

You will work with various raster datasets in the lab, which also include a DEM (Digital Elevation Model). You will use DEM to create contours, vertical profile, hillshade, and other derivative surfaces such as slope and aspect. You will also learn how to build a TIN using a DEM.

Finish all tasks in Chang’s Chapters 4 and 13. Answer and submit all questions listed at the end of this exercise. Lab exercise data are available in: I:\Students\Instructors\Geoffrey_Duh\GEOG4575\Chang_5e\chap4 and 13 (or on the textbook CD). Please copy all these folders to your working directory in c:\Users before you start.

Additional note:

Chapter 13, Task 2, Step 2 in 2.1. You will have to select “Equal Interval” for classification method first, before you can change the number of classes to 5.
Chapter 13, Task 3, Step 3. Alternatively, you can use the “Add Features to TIN” in the “Create/Modify TIN” submenu of 3D Analyst’s pulldown menu to complete this step.

Questions:

1) Use ArcCatalog to find the header information of the DEM, Menan-Buttes, that you imported in Chapter 4 Task 1.

Raster Data Format	GRID
Planar distance units
Vertical Z units
Cell size (x, y)
Number of cells on x (column), y (row)
Data type of cell (pixel type)
Number of bits per cell (pixel depth)

2) Use ArcCatalog to find the header information of the tmrect.bil that you used in Chapter 4 Task 2. Use the file size calculation we did in class and Windows File Explorer to find the size information of the file. Windows Explorer reports two file size information. Use the file size value not the size on disk value.

Raster Data Format	BIL
Planar distance units
Vertical Z units	NA
Cell size (x, y)
Number of cells on x (column), y (row)
Data type of cell (pixel type)
Number of bits per cell (pixel depth)
Number of bands
Calculated File size (bytes)
File size (report the exact size in bytes, not in KB)

3) Copy only the tmrect.bil file to a different folder and use ArcCatalog to view the file. Report what happen and explain why. Copy the tmrect.hdr to where you put tmrect.bil and use ArcCatalog to view the file. Report what happen. Open the header file (i.e., tmrect.hdr) with notepad. Use ArcGIS online help to decipher the information in the hdr file (search with the “BIL raster files” keywords.) Describe what information is stored in the header file.

4) Use ArcCatalog to find the header information of the DEM, plne, that you used in Chapter 13 Task 1.

Raster Data Format
Planar distance units
Vertical Z units
Cell size (x, y)
Number of cells on x (column), y (row)
Data type of cell (pixel type)
Number of bits per cell (pixel depth)

5) There is a conversion tool called “Features to 3D” in ArcGIS 3D Analyst’s pulldown menu (in the convert submenu). It assigns z values to features in a GIS layer using the values from a DEM. Use this tool to convent the contours (i.e., ctour.shp) that you used in Chapter 13 Task 1into a 3D shapefile. How could you tell the output features are 3D features?

6) You have a DEM and a shapefile containing the locations (i.e., points) of 200 weather stations. Describe the procedures and tools that you would use to create a table showing the elevations of these weather stations. (Hint: Check either the “Extract Values to Points” tool in the “Spatial Analyst Tools-Extraction” toolset or the “Add XY Coordinates” tool in the ‘Data Management Tools-Features” toolset in Arctoolbox.)

7) What are the azimuth and altitude refer to in Chapter 13, Task 1, step 1.3?

8) In Chapter 13 Task 2, what’s the total area (hectare) for areas with a slope > 40 percent?

9) Describe the effects of “Add Features to TIN” on TINs you created in Task 3, Steps 2 and 3. Insert maps of the TINs before and after the emidastrm.shp was added in your write-up. Also report the numbers of nodes and triangles in both TINs.