Name:
Lab 6: Resolution
Due Date: 9/27 by 11:59 pm
1. SPATIAL RESOLUTION
a. For each of the 3 images, indicate with a checkmark in the table below which
features you can resolve (see). (1 pt in total)
NAPP
Image
(1 m)
Feature
Large area of conifer forest north
and west of Tower
Center pivot irrigation in upper right
corner of image
Devil’s Tower
Belle Fourche River (runs from lower
center to upper right)
Individual trees
Cars in parking lot just west of Tower
v
TM Image
(30 m)
MODIS
Image
(1 km)
v
v
v
v
v
v
v
v
b. Can you see features that are narrower or smaller than the size of a pixel
(e.g., is a road that is less than 30 m wide visible in the TM image?)? If so,
why do you think this would be? (1 pt)
Yes, I think the Devil’s Tower in tm is smaller than the pixel size because it
gives a finer spatial resolution, thus, the level of spatial detail detectable in
TM imagery is better.
c. Based just on differences in spatial resolution, what types of applications
might each sensor (NAPP, TM, MODIS) be good for? For each sensor, provide
a link from which you obtain the answers. (1 pt for each)
The NAPP sensor is good for estimating the system’s cartographic potential
to produce orthophoto quads, digital elevation models, topographic maps,
and digital information to meet National Map Accuracy Standards at
1:12,000 and 1:24,000 scale - chromeextension://efaidnbmnnnibpcajpcglclefindmkaj/https://www.asprs.org/wpcontent/uploads/pers/1993journal/jan/1993_jan_61-65.pdf
The Thematic Mapper has become a useful tool in the study of albedo and its
relationship to global warming and climate change. The TM on the Landsat 5
has proven useful in determining the amount of ice loss on glaciers due to
melting. Landsat 7 carries an enhanced TM sensor known as the Enhanced
Thematic Mapper Plus (ETM+) https://en.wikipedia.org/wiki/Thematic_Mapper
The fire detection algorithm uses MODIS to detect active fires. The MODIS
instrument tracks land use change by examining its spectral properties over
the land. It also collects data about ocean and atmosphere about every 2
days - https://gisgeography.com/modis-satellite/
d. How many NAPP pixels fit in a TM pixel? How many NAPP pixels fit in a
MODIS pixel? Use scientific notation if the number is too large. (1 pt for each)
e. Use Windows Explorer to look at the file size of each of these images on the
computer. How do the file sizes compare? Why? (1 pt)
2. SPECTRAL RESOLUTION
a. Can you see the shape of the classic vegetation reflectance curve in the
graph you created for the NAPP data (note that band 1 = NIR, band 2 = red
and band 3 = green in this image)? Attach a screen shot. What are the
important characteristics of this curve at this spectral resolution (Hint:
reflectance and absorption)? (1.5 for the answer and 0.5 pt for the screen
shot)
b. How about in the curve from the TM image? Can you make out the general
shape of the spectral response of green vegetation? Attach a screen shot.
What are the important characteristics of this curve at this spectral
resolution (Hint: reflectance and absorption)? (1.5 for the answer and 0.5 pt
for the screen shot)
c. How about the curve from the AVIRIS data? Can you see the shape of the
typical vegetation spectrum? Attach a screen shot. What are the important
characteristics of this curve at this spectral resolution (Hint: reflectance and
absorption)? (1.5 for the answer and 0.5 pt for the screen shot)
d. Look at the image downloaded from a spectral library on the web. What are
the deep dips in reflectance (wavelengths 1.5 um and 2.0 um)? Can you see
these dips in the AVIRIS curve you generated? Why or why not? (Hint:
Lecture6_ARRS_2.pptx) (1 pt)
3. RADIOMETRIC RESOLUTION
Reference this link to help answer the following questions. Remember to show
your work to earn full points.
a. A MODIS image covers an area of 2330 km at one side and 10 km at the
other side. If you’re going to use bands 3-7 for your research, how many
MODIS pixels are there in one band? (2 pt)
b. How many bands are there in a MODIS image? (1 pt) Which band was
designed primarily for ozone? (1 pt)
c. Suppose that all the bands contain the same numbers of pixels as your
derived from question 3a, how many DNs (digital numbers) are there in one
image? (2 pt)
d. What is the range of DN values if a MODIS sensor has a 12-bit radiometric
resolution (unsigned integer)? (Extended reading for your own interest) (2
pt)
e. How many gigabyte (binary) are required to store the image on a hard drive?
(Hint: convert bytes to gigabytes) (2 pt)