Geography Reference
In-Depth Information
not encouraged. As for soils, you would like to favor the very suitable soils (type 3) over the moderately
suitable soils (type 2). The streams requirement is still firm, however.
When you solved the Wildcat Boat problem with vector data, the study area was partitioned into two
categories: where building could take place and where it couldn't. What you could do easily now, with
raster processing, is to display areas of greater or lesser degrees of suitability. You do this by going
back to reclassification. Keep in mind that you are going to combine the values of the zones. In the last
exercise you simply added the four rasters together (each Value variable being either 0 or 1) and took only
those zones with value 4 as the sum that was acceptable. But consider the flexibility you have with raster
processing and reclassification. Through reclassification you could make the most desirable areas have
large sums, while the prohibited areas have small or even negative sums.
For example, you could reclassify the sewers—making the value 10 for areas within the 300 meters, and
5 for areas outside that distance, since it's now permissible to build outside the defined area, but not as
desirable.
Regarding Landuse, you could make brushland (code 300) and agricultural land (code 200) have value
10—because they are now both acceptable—but forested land (code 400), which is acceptable but less
desirable, have a value of only 7. For other, prohibited Landuse codes—100 (urban), 500 (water), and 700
(barren)—you could reclassify those areas with a negative number (say,
−
100), so the zone would show
a negative value after raster addition takes place.
Regarding Soils, you could use 6 for moderately suitable (code 2) and 10 for very suitable (code 3). What
about the prohibition regarding building on unsuitable soil? Again you could reclassify those areas with a
large negative number so the zone would show a negative value after raster addition takes place.
What about the streams requirement? You could reclassify the NOBUILD area as negative 100, while the
permissible areas could have value 10.
If you added these four reclassified rasters, you could have zones with value 40 for the most suitable,
and smaller values for less suitable areas. For example, a zone depicting an area outside the 300-meter
sewer zone (reclassified as 5), on forested land (reclassified as 7) that was only moderately suitable
for building (reclassified as 6) would be 28. (You would know that any area that came out negative was
prohibited.)
31.
A summary of the reclassifications and suggested names for the new rasters are provided
below. Put the new rasters in
___IGIS-Arc_
YourInitials
\Spatial_Analyst_Data
\WC_Boat_SA\Wild_Cat_Boat_SA.mdb
Reclassify Sewers_buf_rr2m to make rcl_version2_Sewers_buf
OLD VALUES
NEW VALUES
300
→
10
NoData
5
→
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