Introduction to Satellite Remotely Sensed Data
for the Vancouver Area

Due: Beginning of your lab next week.

Marks: 47

Background Information

In this lab you will be looking at a series of remotely sensing images of Vancouver. You will be using GIMP--a simple image viewer program--to look at the images. It is accessible from Start / All Programs / GIMP / GIMP 2 or as an icon on your desktop. GIMP is 'open source'; therefore you can download it and use it for digital photo manipulation. It is similar to Adobe Photoshop and very useful for digital picture manipulation. You will be using it in this lab in order to get familiar with satellite images, resolution, etc., before using the more complex image processing software program IDRISI. The images you will be viewing were derived from a number of sources and contain data obtained from a number of different bands. The images were provided by Nicholas Coops, Faculty of Forestry, UBC.

In order to complete this lab exercise you will have to do some independent research and look up some information on the web in order to gain an understanding of the type of sensor carried by various satellites, and of the bands associated with the different sensors. For example, what are the MSS-TM bands on the Landsat Satellite?

Getting Started

1. On your desktop, you should have an icon GetData. Click on this, then select g373, and then click on OK. Click on the Lab 3 button. Click on Yes to load the data, and then on OK to close the notification window (note: it can take some time for the data to be downloaded). Once the black pop-up window disappears, click on Exit. The data will be loaded into the C:\Data directory. Since you will not be altering these images in this lab there is no need for you to save the images to your home directory on the H: drive. When you log off, the data (images) will be cleared from C\:Data directory. If you do not finish the lab within your lab time, you can simply run GetData again. Important: Do not store any data on your desktop, as that will slow down your login to the computer.

(Note: For those familiar with ArcMap, the entire exercise can be conducted using that program. Simple load each file into ArcMap (you may need to right-mouse click "Zoom To Layer" to view the different images) and answer the questions accordingly.)

2. Start the GIMP 2 Software.

a. To open an image, click on FILE, then OPEN and select the relevant image from the C:\Data directory. (Ignore any TIFF warnings or errors that may appear when opening an image.)

b. Once loaded, click on VIEW and then on NAVIGATION WINDOW. Use the small navigator window to zoom and pan and then examine the images in the larger window.

Assignment

1. OPEN the Quickbird.tif Image. Use the navigator window features to pan around and zoom in and out of the image. This image of Vancouver was captured by the Quickbird sensor.

1a) Zoom into an object with a known size and determine what you believe the pixel size of the image to be (i.e., the spatial resolution). Provide justification for your reasoning. (2)

1b) The image was georeferenced, which oriented it such that north is to the top of the image. Given this information, where was the position of the sun when the image was taken? Looking at sections of downtown Vancouver, what is the effect of this sun position in the image? (2)

1c) This image was taken on 25 July 2003. Why does the forest in Stanley Park not look uniform? Provide some possible explanations, including the time of year. (2)

1d) This image is known as a "panchromatic" image. What does this mean? Find the spectral range of the Quickbird Panchromatic sensor using GOOGLE. (2)

1e) Pan to a portion of the image covering water. Some areas of the ocean are black, while others have patterns and are lighter. Provide some reasons for this variation in the appearance of the water. (2)

2. OPEN the Landsat7-pan.tif panchromatic Image. Use the NAVIGATOR window to pan around and zoom in and out of the image.

2a) Again, find a feature on the image and determine the apparent pixel resolution of this scene. Make sure you provide a justification for and the workings of your estimate. (1)

2b) Zoom the image over Stanley Park. List 4 differences that you observe between this Landsat image and the previous Quickbird image. (2)

2c) Given that this image would cost 10% of the cost of the previous Quickbird image, list some possible uses / applications (and advantages) of using a Landsat image over a Quickbird image. (2)

3. OPEN the Landsat99.tif Image. Use the NAVIGATOR window to pan around and zoom in and out of the image.

3a) This is a "true colour" Landsat image, taken at the same time as the Landsat panchromatic image you explored in question 2. How can you tell the images were taken at the same time? (2)

3b) If this image is 'true colour', what does that imply about the relation between the spectral bands of the image and the monitor's (RGB) colour assignment? (2)

3c) View the UBC Campus. Landsat multispectral imagery has a spatial resolution of 30m. Different types of vegetation appear in different shades of green. Provide an explanation as to why this may be the case. Include the golf course, forest, and tree lined streets in your explanation. (2)

4. OPEN the Landsat85.tif Image. Use the NAVIGATOR window to pan around and zoom in and out of the image.

4a) This is another "true color" Landsat image, but this imagery was collected in 1985. Display the 1999 and 1985 images side by side. Look at the UBC Campus and the surrounding area. List 2 changes between the two dates. What might have caused these changes? (4)

4b) On both Landsat images there is significant water discoloration. Why does this discolouration appear as blue and green? (2)

5. OPEN the ASTERVNIR15.tif Image. Use the NAVIGATOR window to pan around and zoom in and out of the image.

5a) This image is a VNIR image from the ASTER sensor. Use GOOGLE to find out more about this sensor. Write a paragraph on the sensor, its platform and image applications. What spectral bands are included in a VNIR image? (4)

5b) The ASTER image is bright red. Why? (1)

5c) This image has a 15 m spatial resolution, which is the same resolution as the panchromatic Landsat image display in Question 2 (colour Landsat has 30m resolution). Give examples of where your ability to discriminate objects or land cover types would be enhanced by the spectral (colour) information from the ASTER image. (3)

6. OPEN the 120m.tif Image. Use the NAVIGATOR window to pan around and zoom in and out of the image.

6a) This image has a much coarser spatial resolution: 120 meters. It is also sensing a different part of the spectrum. Make an educated guess as to what part of the spectrum is being sensed, and explain why we would acquire an image using this spectral band.(3)

7. OPEN the RADARSAT.tif Image. Use the NAVIGATOR window to pan around and zoom in and out of the image.

7a) This is a RADAR image rather than an optical image. Describe 2 differences between this and all of the previous (optical) images. (2)

7b) If there were clouds in the image, how would they appear? (1)

7c) This image has the same spatial resolution as the Landsat MSS image (30m), but some objects are much more obvious than in the Landsat image, such as the street pattern and ships in the harbour. Provide an explanation as to why this might be the case. (2)

7d) RADARSAT was the first 'Canadian' Satellite. GOOGLE RADARSAT and write a paragraph describing the history of the satellite, its major applications and basic specifications. (4)