Lab 4: Raster and Terrain Data Manipulation

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

Due Oct 28 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:\Students before you start.

Additional notes:

Chapter 4, Task 1. ArcGIS 10 can decode a raster STDS catalog/directory data descriptive file (XXXXcatd.dff) and open the data (cel0.ddf) associated with the catd.ddf file. You will need to change the symbology, which activates the calculation of raster statistics, to view the image. Once the data set is added to ArcMap, you can use the export option of the layer to save the file to other formats.
The tools that were originally on the Spatial Analyst menu (e.g., Contour) can be found in ArcToolbox in ArcGIS 10.Use the ArcMap's search function to find the tools mentioned in the instructions.
The graphic user interface (GUI) of ArcScene in ArcGIS 10 is different from previous versions. When setting the Base Height, check the "Floating on a custom surface" and point the surface to the DEM you use in lab.
Chapter 13, Task 3, Step 3. The Edit TIN tool is in TIN Management toolset in ArcGIS 10. This tool modifies the input TIN. You can use the original DEM to create another TIN to compare the effects of the Edit TIN tool on the TIN.

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. Report the file size value not the size on disk value in the table below.

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 By Attribute" in ArcGIS. It assigns z values to features in a GIS layer using the values from an attribute field. Use this tool to convert the contours (i.e., ctour.shp) that you used in Chapter 13 Task 1into a 3D shapefile (use the CONTOUR field as the height field). How could you tell the output features are 3D features? Use ArcScene to verify the result.

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 an Excel spreadsheet 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 "Edit TIN" on TINs you created in Chapter 13, Task 3, Steps 2 and 3. Insert maps of the TINs before and after applying the Edit TIN tool in your write-up. Describe the options the Edit TIN tool has to incorporate the elevation information of the input feature class when modifying the input TIN.