Why doesn't Map Center mark the right house on the Air Photo
when it finds my address?
Map Center uses a strategy called geocoding to take a written
address (like 1025 2nd Ave) and locate it on a map. Geocoding usually
does find the right block for your address, but it usually does not
find the exact location along the block when marking your address.
Here's why: Map Center knows the starting and ending addresses
on each side of every street block in Oakland, but doesn't know exactly
where each house is along the block. So, when Map Center marks your address
along the block, it uses interpolation. With interpolation, Map
Center divides up the street evenly between the starting and ending addresses
and marks your address at the right division point. For instance, on an
imaginary street with only three addresses (#1, #2, and #3), Map Center
would divide up the street into three points. If your address was #2, Map
Center would place the mark for #2 in the middle of the block, even though
the house with address #2 isn't exactly in the middle of the block. Because
most houses are not evenly distributed along their blocks, Map Center's
mark may not match your house's actual location in the air photo.
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Using a real example, one of the blocks of Whittle Avenue starts with the
addresses 3900 and 3901 and ends with the addresses 4098 and 4099. When you
ask to see the location of 4007 Whittle Avenue, Map Center first figures out
that your address is odd, not even, and so it will be on the North side of
Whittle Avenue. Then Map Center interpolates the location of 4007 and
marks this interpolated spot on the map.
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As you can see from the air photo, Map Center's interpolated guess
about the location of 4007 Whittle Avenue does not match the real
location of the house at 4007 Whittle Avenue. Geocoding is a useful
tool for finding the approximate location of an address, not the
exact location of a house.
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Frequently Asked Questions:
1.
Where did the map data come from?
2.
How do these interactive internet maps work?
3. Why doesn't Map Center mark the right house on the Air Photo
when it finds my address?
4.
How many maps have these sites created?
5.
Why do Map Center maps have a different look and feel from other
internet maps?
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