Re: Dash cams

Cameo <[email protected]> wrote:

> IR won't illumanate far ahead and it might reflect back from the 
> windshield glass.

https://i.stack.imgur.com/O9HxM.jpg

Windshields are not designed to trap IR as does greenhouse glass.  There
is some reflectivity, but the same applies to the light from outside
that you use to see the road.  The windshield does have a layer of
plastic, and I didn't bother to check absorption and reflection for it.

I doubt there would be dash cams with IR LEDs if they were ineffective.
Also, not everything that happens to your car occurs at speed.  For
example, the G-sensor in a smartphone can be used to detect collisions
along with break-ins while the car is parked.

I suspect a much larger sensor would pickup more light under dim lit
conditions.  Yep, size does matter.  Typically die cost is not linear
with increased size, but more like exponential.  I didn't dig into the
costs for various sizes of CMOS sensors.  CMOS rather than CCD works
better under low-light conditions.  

https://www.fierceelectronics.com/embedded/growing-world-image-sensors-market

That notes CMOS sensors range in cost from $4 to $10.  Might not seem
like much to you, and would qualify as an incremental cost, but would
result in a camera with lesser quality, features, sturdiness, and other
traits getting priced out of its market target.  Besides the cost of the
sensor, other parts would have to become more robust which also raises
the cost of the product.

There are dash cams that have high quality for video and good
reproduction under dim lighting, but they are not incrementally more
expensive, but more like explosively more expensive.  You can get a
better dash cam *if* you're willing to pay the much higher price.  Plus,
dash cams are not designed to substitute as cameras.  They are not to
record your vacation as you travel from resort to theme park for viewing
later with high quality video replay.  Instamatics were popular years
ago, too, despite picture quality was poor.