[GRASS-dev] Re: [GRASS-user] low radiance values after i.atcor and i.topo.corr

[Markus Neteler]

On Sat, Jun 21, 2008 at 6:39 PM, Glynn Clements
<glynn at gclements.plus.com> wrote:
> Markus Neteler wrote:
> I'm just not familiar with the specifics of i.cluster (e.g. whether it's finding
> clusters in geographic space or colour space, what the output
> signifies, etc).

It takes several maps and builds up a multi-dimensional feature space
from the pixel (spectral, ...) values. Those are then clustered.
...
>> What's needed since we cannot change the format
>
> No? If the format was changed to %g (i.e. like %f for "typical"
> values, like %e for particularly large or small values), it would
> remain compatible with anything using scanf("%f"), atof(), strtod()
> etc, as those functions all understand exponential notation.

Ah, sounds good.

> [About the only plausible situation where switching from %f to %g or
> %e can cause problems is when code tries to match FP literals against
> a regexp such as "[0-9]+\.[0-9]*".]
>
> You would need to add an explicit scale= (e.g.) option. As there's no
> way to pass the scale factor out to the user, the user would have to
> pass the scale factor in.
>
> OTOH, a scale= option and switching to %g aren't mutually exclusive;
> but %g would largely eliminate the need for scale=, and would probably
> be more useful.

If there is no scanning problem, I would appreciate to just increase
the precision and don't introduce a scale parameter. I guess it then
just works.

Markus