Technique 2: Manual GIS
Element 1: Making Feature Overlays
Materials:
1997/1993
1:24,000 scale San Mateo, CA / Redwood City, CA, USGS Topographic Quadrangle
(2) 11”x 17”
clear film overlay
drafting tape
Colored
marker pens: Red, Blue, Black
Exercise:
1. Use
the 1:24,000 scale San Mateo, CA / Redwood City, CA, USGS Topographic
Quadrangle.
2. Use clear film 11”x
17”overlay.
3. Tape clear film overlay
on top of 1:24,000 scale map. Tape at the top edge.
4. Use the Blue pen.
5. Use the Blue pen to
make four “corner marks” (tick mark ^) on the overlay, one at each corner of the
study site.
6. Trace the shoreline in
Blue on the overlay.
7. At the bottom of the
overlay (in Blue) draw a short horizontal line and label beside it “1997/1993
Shoreline.”
Hint: Use of a symbol with a short description beside it
is a “key,” or means of identifying selected features.
8. Remove the “1997/1993
Shoreline” overlay.
9. Use a second 11” x 17”
clear film overlay.
10. Tape the film overlay on top of the 1:24,000
scale San Mateo, CA / Redwood City, CA, USGS Topographic Quadrangle. Tape
at top edge.
11. Use the Red pen.
12. Use the Red pen to make four “corner
marks” (tick mark) on the overlay, one at each corner of the study site.
13. Outline areas of marsh in Red on the overlay.
14. At the bottom (in Red) draw a polygon (circle)
and label it “Marsh.”
15. Remove the “Marsh” overlay.
16. Use the third 11” x 17” clear film overlay.
17. Tape the clear film overlay on top of the
1:24,000 scale San Mateo, CA / Redwood City, CA, USGS Topographic Quadrangle.
Tape the top edge.
18. Use the Black pen.
19. Use the Black pen to make four “corner marks”
(tick mark ^) on the overlay, one at each corner of the study site.
20. Outline all mudflats on the overlay.
21. At the bottom (in black) make a polygon
(circle) and label it “Mudflat”
Hint: Combining several single “key” items creates a
“legend.” Every map should have a legend
22. Tape the “Shoreline” and “Marsh” overlays one on top of each
other, over the “Mudflats” overlay. Use the four corner marks to line-up
(“register”) the overlays on
top of each other.
Hint:
Tape one overlay at the bottom edge and the other overlay at the left or right
edge. By attaching the overlays at opposite edges, you can flip the
overlays up and down in various alignments.