Hello Jonny,
I assume that this is not possible. Are the holes in your elevation data big?
I would suggest that you interpolate the missing data. This can be done tools from gdal-library:
http://www.gdal.org/
Ready compiled packages are available for Windows from OSGeo4W http://trac.osgeo.org/osgeo4w/
(OSGeo4W Installer)

To fill the holes you need to do:
1. copy the elevation matrix to a separate text file ie. dem.txt

2. add a header to the text file that it looks like:
ncols        366
nrows        366
xllcorner    0.000000000000
yllcorner    -366.000000000000
cellsize     1.000000000000
471.2 473.3 482.9 489.5 492.3 ...
447.7 449.8 453.8 456.4 457.2 ...
...
you have to adapt the ncols, nrows and yllcorner values to fit to your matrix size (in my case 366 by 366 values)

3. convert and mark nodata values with gdal_translate. "0" is the value for nodata
in OSGeo4W Shell:
> gdal_translate -a_nodata 0 dem.txt demnodata.tif

4. fill the nodata regions by
in OSGeo4W Shell:
gdal_fillnodata.py demnodata.tif filled.tif

5. convert back to ascii matrix
in OSGeo4W Shell:
gdal_translate -of AAIGrid filled.tif filled.txt

Remark: the produced *.tif files can not be displayed in every image viewing software as it contains no the usual RGB data but instead integer or float valus. One nice software to display (and even analyze) is ImageJ: http://imagej.nih.gov/ij/

Best regards
Wolfgang

Am 03.07.2013 21:46, schrieb Jonny Prouty:

Hello all,

My apologies in advance if I've overlooked something, but is there a way to instruct Loch to NOT draw elevation data equal to a certain value? For instance, in my current model, I do not want Loch to draw any elevations that are equal to 0. Is this possible? Thanks very much in advance!

Cheers,

Jonny ^v^
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