Alpine INE-W940 Owner's Manual page 61

Distance guidance mark
The distance guides represent the ground level distance from the rear
bumper. It is difficult to accurately estimate the distance to objects
above ground level.
<Screen>
<Positions of A, B and C>
about 1 m
In the screen, according to the distance guidance marks,
the truck seems to be parked about 1 m away (at the
position B). In actual fact, however, if you reversed to
position A, you would collide with the truck.
In the screen, positions A, B and C seem to be located in
order of proximity. However, in actual fact, the position A
and C are the same distance, and B is farther away than
positions A and C.
• The car width extension mark represents the distance to the road
surface. The distance to an object on the road is not accurately
represented by the guides.
• In the following conditions, screen visibility may be impaired. This is
not a malfunction.
- When it is dark (during the night, etc.).
- Under very high or very low temperature conditions.
- When water drops adhere to the camera, or when the humidity
is high (such as rainy weather, etc.).
- When foreign bodies (such as mud, etc.) adhere to the camera
or its peripheral area.
- When sunlight or headlights directly strike the camera lens.
- When a CCD camera is connected, smearing* may occur. This
phenomenon is peculiar to CCD cameras.
* Smear phenomenon:
A phenomenon which occurs when a high-intensity spot (such
as a reflection of the sunlight on a car body) is shot by the
camera. The picture below is an example of 'vertical smear'
common to CCD cameras.
C
B
A (about 0.5 m)
A high-intensity spot
Error between the screen and the actual road surface
In the following conditions, errors are produced between the screen
guidance and the actual road surface. (The illustrations represent a case
when the camera is installed in the standard position.)
When there is a steep upward slope behind the car
(example)
<Screen>
Distance guidance marks
<Situation of the car>
The distance guidance mark represents the distance to a
flat road surface. Therefore in the case of an upward
slope behind the car, the distance guides are displayed
closer to the rear bumper than the actual distance. For
example, if there is an obstacle on the upward slope, it
may appear farther away than its actual position.
Also, an error may occur between the guidance and the
actual path of the car on the road surface.
Actual distances
Error Error
61
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