GEOG 385.02/GTECH 785.02 |
GIS SG course homepage |
Start: |
2/11 |
Due: |
2/18 |
Data: |
Print this page and pick up Handouts A and B. |
Turn In: |
Handouts and answers to the questions below |
Sign your handouts and this page _______________________________________________________.
Using Handouts A and B, fulfill the
assignment following the instructions below and answer the questions in the
space provided. Answers should be short (one word or 1-2 full
sentences). Write clearly please. If you do not have enough space, please
attach an additional page.
Handout A.
1. For each feature shown on the vector map,
prepare the necessary information to describe this feature:
1.1. Determine Feature ID, Feature Type (point,
line, or polygon), and number of its constituent elements (number of points in
each feature).
1.2 Include this information
into your description of features and present it in the following table:
Feature: |
Path |
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Feature: |
Birch Stand |
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Feature ID: |
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Feature ID: |
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Feature Type: |
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Feature Type: |
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Number of points: |
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Number of points: |
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Points: |
X: |
Y: |
Points: |
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Y: |
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EXAMPLE:
Feature: |
Fountain |
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Feature ID: |
11 |
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Feature Type: |
Point |
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Number of Points: |
1 |
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Points: |
X: |
Y: |
1 |
0.5 |
4.5 |
2. Present the same portion
of the Central Park in raster format using the raster grid provided. Assume
that coordinate origin is in the lower left corner as it is in the vector
format.
2.1. Shade pixels with non-zero attribute values
with different colors (make sure that you can see the values):
11-red 2-yellow 5-blue
7-green
2.2. What is the total number of attribute values in this raster file?____________
2.3. Vizually compare both types of representations of Central Park. What format (raster or vector) suits better for representing spatially discrete features?
2.4. If you used 100 by 100 raster grid
instead of 8 by 8 grid to show the same area, would the representation of
features in raster improve? Why?
Handout B.
3. Examine raster digital elevation model of the
area. North is on the top, South is on the bottom.
3.1 Determine whether the following statement
is true of false:
In general the elevation increases from
South-West to North-East.
True / False (circle one answer)
3.2 The maximum elevation in this image is__________ ft.
3.2 The number of pixels with maximum elevation values is _______.
4. Convert this raster surface into vector contour lines. Contour lines connect points with equal elevation. Draw only THREE contour lines using the vector coordinate system provided. These contour lines should be at the elevation of 0, 1, and 2 feet. Label the countour lines with these values.
NOTE: When converting raster values to vector format, remember that a vector point is created in the center of the pixel.
4.1 Do any vector features or values exist
between the contour lines? Why?
4.2 If you had a raster grid 100 by 100
instead of 8 by 8, it would show finer variation in elevation in this portion
of Central Park. Would your resulting contour lines be smoother or rougher?
4.3 Which format (raster or vector) is better for representing continously changing phenomena such as elevation? Why?