Canada Centre for Remote Sensing
Tour Canada from space
Melfort, Saskatchewan
Larger, more detailed
image here: 333kb jpg
How would you go about gathering information about
agricultural activity across Canada? Groups like the Canadian Wheat
Board and Agriculture and Agri-Food Canada certainly don't drive to
every field collecting data on crop acreage and yield. Instead,
they use remote sensing data that provide coverage of very large
areas in an efficient and timely fashion. But what if there is
cloud cover, fog or rain - all of which are common in the summer
months when crop information is collected? These conditions would
impair data acquisition by optical sensors (like the LANDSAT
"Thematic Mapper") at important stages of crop development. The
answer: microwave remote sensing. More typically known as radar
remote sensing, this technique is being studied intensively for its
potential applications in agriculture because of its unparalleled
advantages. These advantages make radar remote sensing perfect for
collecting information about crop type, area, yield, conditions,
and practices, especially over large areas. This synthetic aperture
radar (SAR) image of the Melfort area can not only be used to show
an overview picture of the city and
the agricultural activity in the area, but also to determine
different crop types, detect
variations in crop health or growth stages within individual fields, and it can be
used for crop inventory via image "classification".
Question: Why is radar remote sensing considered much more
useful than optical for data acquisition during cloudy, foggy, or
rainy weather?
[
Answer ]
About this Image
| Location: |
Melfort, Saskatchewan |
| NTS
map(s): |
73 A/15 (1:50,000) |
Location Map:  |
See a detailed map (1:1M) of the
region |
| Image Date: |
July 31, 1983 |
| Satellites/Sensors: |
CCRS CV-580 Airborne SAR,
C-VV |
| Resolution: |
Approximately 9 metres
pixels |
| Image Area: |
Approximately 10 km by 6
km |
| Image Features: |
Crop types, within-field
variation, city of Melfort, image classification |
| Related Tour Images: |
Altona, Manitoba; Niagara Falls, Ontario; Fredericton, New Brunswick;
Essex County,
Ontario |
| Related Glossary
Terms: |
These terms from the CCRS Glossary may help you to
understand this image and its interpretation:
image
classification, contextual
classification, supervised
classification, image
texture, tone,
brightness,
contrast,
speckle,
speckle
filter
|
| Related Tutorial
Sections: |
These sections of the "Fundamentals of Remote Sensing"
tutorial
by CCRS will help you to better understand this image
and its interpretation:
3.5 3.6 3.8 5.2
|
| Image Credits: |
Some information adapted from Chapter 7 ("SAR
Applications in Agriculture") of "Radar Remote Sensing:
A Training Manual", Dendron Resource Surveys Inc., as
well as from the City of Melfort homepage at www.cityofmelfort.ca.
|
|
| Question: |
Why is radar remote sensing
considered much more useful than optical for data acquisition
during cloudy, foggy, or rainy weather? |
| Answer: |
An airborne synthetic aperture
radar (SAR) like Canada's satellite RADARSAT, collects data
using the much longer wavelengths of the microwave portion of
the electromagnetic spectrum, as opposed to the shorter visible
or infrared wavelengths often used in optical data acquisition.
These longer wavelengths pass easily through clouds and other
atmospheric disturbances, making it possible to acquire images
at times when it is not possible to obtain useful
optical'imagery. The optical wavelengths, however, are more
similar in 'size' to the intervening water and particulate
matter in the atmosphere and therefore interact more easily
with them. Also unlike optical remote sensing, radar permits
the acquisition of high resolution data independently of solar
illumination conditions - which means that images can even be
collected at night! |
