Instructor: Brian Klinkenberg
Office: Room 209
Office hours: Tues 12:30-1:30
Wed 12:00-1:00
TAs: Katie De Rego and Leo King
Office hours in Room 115
Katie: Thur @ 9:00
Leo: Mon @ 10:00
Lab Help: Jose Aparicio
Office: Room 240D
Due: Beginning of your lab next week. (Please note that the labs are due at the BEGINNING of your lab; labs handed in after your lab starts will be marked as late.)
Marks: 36
In the GIC you'll find maps, atlases, study desks and some computers. It is also home to the University Aerial Photograph Collection, which consists of over 350,000 air photos.
Description of air photos
The Collection includes federal, provincial and private air photos dating
from 1922 for many areas in B.C. and some areas of the Yukon. The air
photos form a historical collection, mainly covering urban areas, although many
rural areas have some coverage. While the majority of the air photos held by the GIC
are vertical black and white photos, some colour photos are available for selected
areas, and some oblique air photo, from the mid 1940s, are available for selected areas in BC. The standard format for a vertical aerial photograph contact
print is 25cm x 25cm (10" x 10"). Photos obtained by the government for regular
inventory programs are typically provided at scales of 1:15,000 to 1:40,000.
Special projects (for example, photos taken of Vancouver just before Expo 1986) are flown at
larger scales such as 1:5,000 or 1:10,000. The scales of older photos are often given in chains
(1 chain = 66 feet): 20 chains (1:15,840) and 40 chains (1:31,680) being two common scales. Each photo
is cross referenced to an index map or flight report that indicates the
flight path, flight altitude, date, and time of exposure. The air photographs
are filed according to the air photo roll numbers and are located in the compact
storage units behind the reference area. The staff in the GIC serve the UBC community,
and also many consultants throughout BC. For a complete list of
their services and fees, consult the GIC web site.
To find an air photo:
You can locate photos for a particular area using the index guides, which are based upon the 1:250,000
National Topographic Series (NTS) maps. Once you have the NTS map sheet number
you must also consider:
- the dates of the photos,
- the scales of the photos: for a large area, you would likely work with small or medium scale photos (i.e. 1:40,000 - 1:70,000); for a small area you would likely require a photo with a lot of detail (i.e. 1:10,000 - 1:20,000) and use the large scale indices, and
- the types of photos (b/w or colour, vertical or oblique).
The steps are as follows:
1. Consult the NTS index map for BC or the Gazetteer of BC to determine the correct map sheet number for your general area.
2. Locate the (blue) air photo index book (on the counter) that contains the NTS flight index maps for your area--these maps show the locations of historic air photos projects. The dark lines shown are the actual flight lines of the airplane taking the photos. The flight lines are identified by a prefix label:
then by a 4 or 5 digit number (since 1977, the first two numbers correspond to the date of the photography),
then a roll number circled for every 5th or 10th photo (you must interpolate
between these numbers to identify individual photo frames). All photos are numbered sequentially, usually from 001, and increase in the direction
of the flight. Sequential numbers (e.g. 009, 010) along a flight line indicate stereo pair coverage, meaning that
the photos have 60% overlap and can be viewed 3D.
3. There are often several versions of the same NTS Flight Line index maps. The difference
between the index maps is the date of the air photos. Decide whether you require
recent or historical air photos. The recent air photos are located on the most
recent index map, the oldest on the earliest map in the sequence.
4. Once you have located the air photo numbers, the GIC staff will retrieve
the air photos for you, if they are available in the GIC collection. Not all
of BC is covered from 1930 to the present, and while the
GIC houses some 400,000 air photos, a complete set covering all of the photos described in all of the flight indices would encompass many more photos. The GIC has the photos that are marked in red on the flight index maps.
Meet in the lab (115) for a preliminary orientation session. Your TA will then take you into the Geography Information Centre wherein a GIC staff member will give you a presentation on the air photo collection that will help you with this and the following lab. A general set of instructions on how to calculate scale from aerial images (Vol 1, Module 4: Scale and Measurement [Remote Sensing Core Curriculum]).
For all questions involving calculations you need to show us all of your work (i.e., do not just write down the final answer).
1a) Get a copy of the stereo pair of photos BC 5063:264 and 265. The scale of these photos is approximately 1:12,000. If the image component of a standard air photo, such as these, measures 9" x 9", what is the equivalent ground area in hectares (ha) covered by a photo? (1" = 2.54 cm; 1 ha = 10,000 sq. metres) (2)
1b) What
would be the approximate ground coverage (ha) visible in stereo, given that stereo
pairs typically have a 60% overlap? Provide a figure illustrating the overlap of the two photos. (2)
2a) What is the BC government's TRIM program? Over what time period were the original photos taken for the TRIM program? (2)
2b) At what scales were the original TRIM photos (i.e., the contact prints) typically produced? (1)
2c) How high (in metres) would the plane have been flying when it took the photos, given a camera focal length of 6"? (Photo scale = camera focal length / flying height above ground) (2)
2d) Calculate the Ground Resolution Distance (GRD) for a standard TRIM photograph (assuming a scale of 1:60,000). GRD is the size of the smallest object (in m) that we can distinguish on the ground (in the photo). Assume that the film/print (or system) resolution is 50 line pairs / mm. (Ground Resolution Distance (GRD) = reciprocal of image scale / system resolution) (Your text provides a general discussion of this in section 9.4.2.) (2)
3a) Obtain a copy of photo BC5105-084. Orient the photo so that the roll number is on the bottom left corner. What is the name of the town shown in the photo? (Use GIC air photo indices to help you with this.) (1)
3b) What is the scale of the photo? (1)
3c) A more accurate measure of a photo's scale takes into account the height of the land above sea level (i.e., flying heights refer to the height above sea level, and are not relative to the elevation of the topography itself). In this example, the height of the town is essentially at sea level, so the scale of the photo, as derived from the flying height, is correct when referring to the town. However, the scale can vary considerably in an air photo if the height of land varies significantly. What is the height of the mountain on the photo? (Use a topographic map to help you determine an average height of the mountain top.) What is the corresponding height-adjusted scale of the photo on the mountain top? (1)
3d) Which direction was the plane flying when it took the photo? Explain how you determined the direction. (2)
4a) In 1988 the national park Gwaii Haanas, part of southern Haida Gwaii, was created, amidst a tense confrontation that divided the island’s population, as well as public opinion across Canada and around the world. Logging on Haida Gwaii in these old growth forests was very intense, and, in order to preserve the remaining old growth forests, the park reserve was established. Logging activities just south of Sewell Inlet (just to the west of Louise Island) in the 80's were representative of the intensity of logging that was taking place at the time. What photos highlight the extent of the logging activities just south of Sewell Inlet (provide the flight line, photo numbers, and year in which the photos were taken,as well as the NTS map sheet number)? Remember, the GIC only has the photos marked in red on the flight index. (2)
4b) Have the GIC staff obtain these photos for you. Compare the photos with current images available in Google Earth (KMZ). Write a few sentences on the changes in logging activities from the 1980's to today (what year(s) do the Google Earth images represent?). (3)
5. Obtain the three Vancouver (Delta) large-sized 2002 photos that are available at scales of 1:5,000, 1:10,000 and 1:20,000. In each of these photos you will see an almost square field of crops, with a vertical line down the middle, and a white-ish farm area to the east/right side surrounded by some grass. For this question, you will first calculate distances and areas in photo units (cm) on the photo and then calculate the actual area. Include the area surrounding the farm buildings in your estimate (that is, we are interested in knowing the entire area of the farm lot, which includes the field of crops and the residence, barns, etc.).
5a) For each of the three photos, calculate the N/S vertical length of the field on the photo (in centimeters), and the area of the field on the photo (in centimeters). (You are to calculate the photo length and area, not the real-world length and area.) Show your calculations. Then, calculate the actual area in hectares (ha) of the field. Show your calculations. (3)
5b) Using the mylar dot grids (available from the GIC staff) determine the actual area (ha) of the field on each photograph. Instructions on how to use a dot grid to determine the area off-of an aerial photo can be found here. Show your calculations. (3) (Another useful discussion on making measurements off-of aerial photos can be found here.)
5c) Which method on which photo would be the most accurate estimate of the true area? Provide your reasoning. (2)
Background Information
There are many resources available to you for searching for information on remote sensing on any given topic. One source that provides a wealth of resources is Google Scholar:
1.http://http://scholar.google.ca/
2. Enter the keywords remote sensing environment in the search box and click on Search. (If you include the term '-Book' in your search that will exclude all of the books from your search results.)
3. You should get over a million results.
1. Prepare a list of four papers published in different peer-reviewed journals (not books) that describe an application of remotely sensed data; you must provide the complete bibliographic citation for each article (following standard scientific citation standards, such as presented here). Do not include magazine or newspaper articles, or conference proceedings in your list. (2)
2. Prepare a short (2 paragraph) summary of one of the articles from your list. Briefly discuss how the author(s) used remote sensing information to research and/or answer a particular problem. Provide the full reference for the article, along with information describing the remote sensing data used by the author(s) (e.g., the sensor, the resolution). (5)
Note: when doing your image presentation it might be helpful to search Google Scholar in order to find out some how similar images have been used in research, etc.
Resources: