Lab 5: Addressing a Research Objective

Geog 477- Lab 5 Due December 11, 2006

In this lab you will tackle the research objectives listed below and develop some of your own research questions. You will work in groups of 2-3 and write a lab report in the form of a journal article. Some basic processing steps and specific questions are listed for guidance but feel free to expand beyond these to address the research objectives.

All data are posted in the Data folder on the AFS server: J:\isis\html\courses\2006fall\geog\477\001\Data **Remember to copy and paste these data to your H: drive or a local directory**

Objective I: Depict how the UNC campus changed (spatially and spectrally) using Ikonos imagery from 2002 and 2004

Data: uncsubset2002.img, uncsubset2004.img

First, create a subtraction image from uncsubset2002.img and uncsubset2004.img using the Model Maker tool in ERDAS Imagine. This tool will help you perform a variety of functions and will be useful for addressing Objective II.

 Select Modeler | Model Maker… | from the Imagine toolbar. A Model Maker window and Model tool window will appear.  If you run the cursor over the buttons listed in the Model “tool” window, it will describe each tool in the lower left hand corner of the Model Maker window. Click on the Place a raster object in the model tool and click anywhere in the Model Maker window. A raster object icon will appear in the window.  Now double click on the raster object in the Model Maker window and select uncsubset2004.img for the file input. Click OK.  Repeat these steps for uncsubset2002.img so that you have two raster objects in the Model Maker window. With the pointer tool selected you can click and drag any of the icons to move them around in the window.  To link the two images select Place a function in the model and click anywhere in the window. A circle should appear in the window. Now select Connect inputs to function or functions to outputs and click and hold on the uncsubset2004.img raster object and drag the cursor to the “function” icon. Do this again for the uncsubset2002.img raster object so that each object is linked to the circle (or “function” icon).  Double-click on the function icon to define what you want it to do. Select uncsubset2004.img from the Available Inputs (the images may have $n1 or $n2 preceding their file names). Click on “-“ to subtract the images and select uncsubset2002.img from the Available Inputs box. Click OK  Place a raster object in the model so that you have somewhere to put the subtraction image and attach the function icon to the new raster object with the connection tool. Double-click on the raster object to save the output file to your Geog 477- Lab 5 Due December 11, 2006

directory. Change Data Type to Signed 8-bit and do NOT click “Ignore 0 in Stats Calculation”. Click OK  To run the model, click on the red lightning bolt on the Model Maker window.  Open the subtraction image in a new Viewer

Next, calculate the Normalized Difference Vegetation Index (NDVI) for both images. See http://chesapeake.towson.edu/data/all_ndvi.asp for information on NDVI.

 On the Imagine Toolbar select Interpreter | Spectral Enhancement… | Indices…  Select uncsubset2002.img as your input file and save your output file to your working directory.  Under Output Options select Landsat TM as your sensor and NDVI as the function. Note that although you will not be using Landsat TM imagery for this analysis, its Red and NIR bands coincide with the Ikonos bands 3 and 4

 Click OK  Repeat these steps for uncsubset2004.img  Create a change detection image for NDVI from 2002 to 2004. Include a figure of this image in your report.  To create a scatterplot of the two NDVI images select Interpreter from the main toolbar, and then select Utilities | Layer Stack to stack 2002 NDVI and 2004 NDVI images together. Select the 2002 NDVI image as the input file and click Add  Then select the 2004 NDVI image as the input file and click Add  Save the output file to your working directory  Select Classifier from the main toolbar, and then select Feature Space Image to create a scatterplot between the 2002 NDVI and 2004 NDVI from the stacked image. Choose Gray instead of Color for the feature space (or scatterplot).  Open the scatterplot in a new viewer

Objective II: Examine the spatial and temporal trends in productivity in North Carolina, South Carolina, and Virginia using MODIS NPP, Psnet, NDVI, and EVI 1 km data for years 2000-2004.

The MODIS NPP units are in Kg C/m^2/yr after you multiply by 0.0001. The range for annual MODIS NPP is less than 32700, and a detailed explanation for the values above 32700 is on page 33 of the MOD17 user's guide, available at: http://www.ntsg.umt.edu/modis/MOD17UsersGuide.pdf See http://tbrs.arizona.edu/project/MODIS/ for information on MODIS NDVI and EVI products. Geog 477- Lab 5 Due December 11, 2006

Data: MODIS_npp_2000.tif, MODIS_npp_2001.tif, MODIS_npp_2002.tif, MODIS_npp_2003.tif, MODIS_npp_2004.tif, ndvi_2002_193.img, ndvi_2003_193.img, evi_2002_193.img, evi_2003_193.img, psnet_2002_185.img, psnet_2002_193.img, psnet_2003_185.img, psnet_2003_193.img

Note: The number following the data type and year indicates the Julian date for the NDVI, EVI, and Psnet images.

 Import the MODIS tiff files into img files for years 2000-2004  Open the image for year 2000 in Viewer 1  Examine the image statistics under Utility | Layer Info… in Viewer 1  Export this information by selecting File | Print to File and save the resulting txt file to your working directory.  Repeat the previous 3 steps for each MODIS NPP image and include a table of these values in the final report.

Using the MODIS NPP images, create a new image that depicts the range of NPP values obtained over the five-year period. That is, each pixel value in the new image will be calculated as the difference between the maximum and minimum NPP values found for that pixel in the five year NPP time-series.

Now produce two new images, one of which shows the year of the minimum, and the other showing the year of the maximum NPP.

Examine all three of the images you created, and describe the geographic and temporal variability in NPP that they depict. For example, you should explore questions such as the following: Did the entire region behave in synchrony? Which regions (you might refer to US EPA Ecoregions) exhibited the greatest range in NPP, and which the least? Were there latitudinal and/or longitudinal trends? Can you propose and support with evidence (e.g. from the southeast regional climate center, or USGS, etc.) likely causal factors for the patterns observed? You are encouraged to come up with your own questions instead, or in addition to those above.

Producing the above images will be tricky, and you will need to work together and possibly seek outside help.

Compare the NDVI, EVI, and Psnet data. The Psnet data represent net photosynthesis over an 8-day period. The NDVI and EVI data cover a 16 day period. So before comparing them, you should add the two consecutive Psnet images together (e.g. psnet_2002_185.img, psnet_2002_193.img).

Create a series of scatterplots showing the relationship between NDVI and EVI, NDVI and Psnet, and EVI and Psnet. Do this for both years of data. Discuss the relationships between NDVI, EVI, and Psnet, and describe any differences between the two years. Geog 477- Lab 5 Due December 11, 2006

 To create a scatterplot between two images select Interpreter from the main toolbar, and then select Utilities | Layer Stack to stack the images together. Select the 1st image (e.g NDVI) as the input file and click Add  Then select the 2nd image (e.g EVI) as the input file and click Add  Save the output file to your working directory  Select Classifier from the main toolbar, and then select Feature Space Image to create a scatterplot between the two layers (e.g. NDVI vs. EVI) of the stacked image. Choose Gray instead of Color for the feature space (or scatterplot).  Open the scatterplot in a new viewer

Your completed lab report will be in the form of a journal article. The report should include 2-4 paragraphs for each of the following sections:

1. Introduction 2. Methods 3. Results 4. Discussion

Refer to papers in Remote Sensing of the Environment for guidance on written content and help with formatting.

You will be graded on execution of methods, quality of figures, and ability to communicate information in writing.

Length: 4-6 pages + figures and references

Due: 4pm on Monday, December 11 (Final Exam period)