[GRASS-dev] Re: r.external

[Markus Neteler]

On Mon, Sep 8, 2008 at 11:42 PM, Glynn Clements
<glynn at gclements.plus.com> wrote:
>
> Markus Neteler wrote:
>
>> I have some troubles with the assignment of colors.
>> The map is a FP DTM map, and the d.rast output is
>> all white (while r.univar reports 815886 non-null cells).
>>
>> I assume that this is to to the absence of (some) file
>> statistics (f_quant file?).
>
> The current version writes the f_quant file (although not correctly;
> it forgot to call G_quant_init() first; fixed in r33337).

Backported.

Now, after r.external of a
Band 1 Block=23522x1 Type=Float32, ColorInterp=Gray
map, the color table is gray (so, ok).

Then
r.colors pat_dtm_5m col=elevation
d.rast pat_dtm_5m

leads to a white map.

> It doesn't write a histogram; you can use "r.support -s ..." to create that.

I suppose that this is in GRASS 6:
r.support.stats pat_dtm_5m
Statistics for <pat_dtm_5m> updated
r.info -r pat_dtm_5m
WARNING: category support for [pat_dtm_5m] in mapset [PERMANENT] missing
min=nan
max=nan

r.colors pat_dtm_5m col=elevation
Color table for <pat_dtm_5m> set to elevation

d.rast pat_dtm_5m
 100%

... still white.

> Does the map have the correct bounds?

You mean spatially? Yes (the original gray table works).

> Does it have a colour table (try d.legend)?
d.legend pat_dtm_5m
WARNING: category support for [pat_dtm_5m] in mapset [PERMANENT] missing
WARNING: Category file for <pat_dtm_5m> not available

Apparently not: all "nan".

> Can you provide any information at all about the imported map?

gdalinfo pat_DTM_2008_derived_5m_UTM_WGS84.tif -mm
...
Computed Min/Max=0.000,3758.871
  Overviews: 11761x9755, 5881x4878, 2941x2439, 1471x1220, 736x610,
368x305, 184x153

Could the GDAL histogram be used anyhow (r.support takes a while on
this 2GB file)?
I am on a 64bit Linux box.

thanks
Markus