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Posted by dshtykalo on March 13, 2007, 4:23 pm
can someone tell me the advantages and disadvantages to color and
black & white aerial photography.

thanks in advance!


Posted by Bob Woodham on March 13, 2007, 4:49 pm
> can someone tell me the advantages and disadvantages to color and
> black & white aerial photography.
> thanks in advance!

In the days when film was the medium of choice...

B&W advantages:

1. Stable film base layer + high grey level resolution = precise geometric info
2. Film stable over time (and reproduced well when making copies, for
example onto glass plates)

Color disadvantages:

1. Thin film base layer (to accommodate dye layers) + three "gel" dye layers
leads to geometric instability (in processing and subsequent storage).
2. Impossibility to achieve perfect focus on three dye layers simultaneously
implies loss of spatial resolution (compared to equivalent B&W).
3. Dye layers not stable over time (i.e., "colors" change over time)
4. Degradation in spectral quality significant when producing copies
(i.e., loss of quality significant if not working with the original
film).

Color advantages:

1. Gives more (spectral) information about what you're seeing, rather than
simply about where it is located (geometric).

The major driver for aerial photography historically was map making --
getting things in the right place (geometrically) was paramount.
Traditionalists frowned upon the use of color film in mapping for
reasons I've cited.

No doubt there's more to say. But, I've given you a start.


Posted by dshtykalo on March 13, 2007, 5:06 pm
> > can someone tell me the advantages and disadvantages to color and
> > black & whiteaerialphotography.
> > thanks in advance!
> In the days when film was the medium of choice...
> B&W advantages:
> 1. Stable film base layer + high grey level resolution = precise geometric info
> 2. Film stable over time (and reproduced well when making copies, for
> example onto glass plates)
> Color disadvantages:
> 1. Thin film base layer (to accommodate dye layers) + three "gel" dye layers
> leads to geometric instability (in processing and subsequent storage).
> 2. Impossibility to achieve perfect focus on three dye layers simultaneously
> implies loss of spatial resolution (compared to equivalent B&W).
> 3. Dye layers not stable over time (i.e., "colors" change over time)
> 4. Degradation in spectral quality significant when producing copies
> (i.e., loss of quality significant if not working with the original
> film).
> Color advantages:
> 1. Gives more (spectral) information about what you're seeing, rather than
> simply about where it is located (geometric).
> The major driver foraerialphotographyhistorically was map making --
> getting things in the right place (geometrically) was paramount.
> Traditionalists frowned upon the use of color film in mapping for
> reasons I've cited.
> No doubt there's more to say. But, I've given you a start.

Much appreciated Bob.

The main purpose will be for display and the occasionally
measurement. Our last collection was from 2002, but our city has
grown considerably since then and I want to integrate them into our
online mapping software. Our engineering dept will be using them from
time to time and they were skeptical of the color photos but I think
they will do just fine for what they need.

Thanks again!




Posted by Paul Cooper on March 14, 2007, 7:05 am
On 13 Mar 2007 14:06:42 -0700, dshtykalo@gmail.com wrote:

>> > can someone tell me the advantages and disadvantages to color and
>> > black & whiteaerialphotography.
>> > thanks in advance!
>> In the days when film was the medium of choice...
>> B&W advantages:
>> 1. Stable film base layer + high grey level resolution = precise geometric
info
>> 2. Film stable over time (and reproduced well when making copies, for
>> example onto glass plates)
>> Color disadvantages:
>> 1. Thin film base layer (to accommodate dye layers) + three "gel" dye layers
>> leads to geometric instability (in processing and subsequent storage).
>> 2. Impossibility to achieve perfect focus on three dye layers simultaneously
>> implies loss of spatial resolution (compared to equivalent B&W).
>> 3. Dye layers not stable over time (i.e., "colors" change over time)
>> 4. Degradation in spectral quality significant when producing copies
>> (i.e., loss of quality significant if not working with the original
>> film).
>> Color advantages:
>> 1. Gives more (spectral) information about what you're seeing, rather than
>> simply about where it is located (geometric).
>> The major driver foraerialphotographyhistorically was map making --
>> getting things in the right place (geometrically) was paramount.
>> Traditionalists frowned upon the use of color film in mapping for
>> reasons I've cited.
>> No doubt there's more to say. But, I've given you a start.
>Much appreciated Bob.
>The main purpose will be for display and the occasionally
>measurement. Our last collection was from 2002, but our city has
>grown considerably since then and I want to integrate them into our
>online mapping software. Our engineering dept will be using them from
>time to time and they were skeptical of the color photos but I think
>they will do just fine for what they need.
>Thanks again!


A further advantage of colour for some purposes is that you can use
infra-red sensitive film, which is very useful for botanists and crop
biologists who can then see how much chlorophyll (which reflects
strongly in infrared) is present.

Paul

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